1,720,961 research outputs found
Applying Structural Transition Theory To Describe Enzyme Kinetics In Heterogeneous Systems
No full textEnzyme action was investigated by assuming the occurrence of different states of enzyme-substrate affinities. These states were considered to involve enzyme species with distinct abilities to form reaction product. The results obtained showed strong agreement with the experimental data for the action of peroxidase. This approach provides a powerful tool for predicting the kinetic behavior of other enzymatic processes in conditions not described before. An additional feature of this approach is the ability to characterize processes at any enzyme-substrate concentration ratio, including high enzyme-substrate ratios and enzyme inhibition by substrate or product. This proposal can also be used in systems with heterogeneity concerning the investigated enzyme. © 2014 Springer International Publishing Switzerland.52614971513Cornish-Bowden, A., (2012) Fundamentals of Enzyme Kinetics, , NY: WeinheimMonod, J., Wyman, J., Changeux, J.P., (1965) J. Mol. Biol., 12, p. 88Koshland Jr., D.E., Nemethy, G., Filmer, D., (1966) Biochemistry, 5, p. 365Imai, K., Yonetani, T., (1975) J. Biol. Chem., 250, p. 2227Ackers, G.K., Johnson, M.L., (1981) J. Mol. Biol., 147, p. 559Edelstein, S.J., (1996) J. Mol. Biol., 257, p. 737Michaelis, L., Menten, M.L., (1913) Biochem. Z, 49, p. 333Monod, J., (1949) Annu. Rev. Microbiol., 3, p. 371Bispo, J.A.C., Bonafe, C.F.S., de Souza, V.B., Silva, J.B.A., Carvalho, G.B.M., (2011) J. Math. Chem., 49, p. 1976Bajzer, Z., Strehler, E.E., (2012) Biochem. Biophys. Res. Commun., 417, p. 982Bersani, A.M., Dell'Acqua, G., (2011) Math. Method. Appl. Sci., 34, p. 1954Bispo, J.A.C., Bonafe, C.F.S., Koblitz, M.G.B., Silva, C.G.S., Souza, A.R., (2013) J. Math. Chem., 51, p. 144Tzafriri, A.R., (2003) Bull. Math. Biol., 65, p. 1111Schnell, S., Maini, P.K., (2000) Bull. Math. Biol., 62, p. 483Briggs, G.E., Haldane, J.B., (1925) Biochem. J., 19, p. 338Weber, G., (1972) Biochemistry, 11, p. 864Weber, G., (1982) Nature, 300, p. 603Weber, G., (1984) Proc. Natl. Acad. Sci. U. S. A., 81, p. 7098Weber, G., (1986) Biochemistry, 25, p. 3626Weber, G., (1992) Protein Interactions, , New York: Chapman & HallWyman Jr., J., (1948) Adv. Protein Chem., 4, p. 407Wyman Jr., J., (1964) Adv. Protein Chem., 19, p. 223Shannon, L.M., Kay, E., Lew, J.Y., (1966) J. Biol. Chem., 241, p. 2166Hammer, F.E., Oxidoreductases (1993) Enzymes in Food Processing, p. 233. , T. W. Nagodawithana and G. Reed (Eds.), New York: Academic PressGaspar, T., Penel, C., Thorpe, T., Greppin, H., (1982) Peroxidases, 1970-1980: A Survey of Their Biochemical and Physiological Roles in Higher Plants, , Geneva: Université de Genève, Centre de botaniqueMclellan, K.M., Robinson, D.S., (1981) Food Chem., 7, p. 257Alencar, S.M., Koblitz, M.G.B., (2008) Bioquímica De Alimentos, , Rio de Janeiro: Guanabara KooganMorales-Blancas, E.F., Chandia, V.E., Cisneros-Zevallos, L., (2002) J. Food Sci., 67, p. 146Aibara, S., Yamashita, H., Mori, E., Kato, M., Morita, Y., (1982) J. Biochem. (Tokyo), 92, p. 531Bispo, J.A.C., Bonafe, C.F.S., Joekes, I., Martinez, E.A., Carvalho, G.B.M., Norberto, D.R., (2012) J. Phys. Chem. B, 166, p. 14817Bispo, J.A.C., Silva, C.M.R., Bonafe, C.F.S., Assis, D.J., (2013) Dry. Technol., 31, p. 100
Entropy And Volume Change Of Dissociation In Tobacco Mosaic Virus Probed By High Pressure
No full textVirus dissociation and inactivation by high pressure have been extensively studied in recent decades. Pressure-induced dissociation of viral particles involves a reduction in the Gibbs free energy of dissociation and a negative change in volume. In this work, we investigated the combined effect of high pressure and temperature on the dissociation of tobacco mosaic virus (TMV). We assumed the presence of two states of TMV with different tendencies to dissociate. Thus one form presents a low tendency (L) and the other a high tendency (H) to dissociate. Based on the model described here, the L-H transition was favored by an increase in pressure and a decrease in temperature. The volume change of dissociation was pressure- and temperature-dependent, with a highly negative value of -80 mL/mol being recorded at 0 C and atmospheric pressure. The entropy and enthalpy of dissociation were very temperature- and pressure-dependent, with values of entropy of 450 to -1300 kJ/mol and values of enthalpy of 5.5 × 104 to 2.4 × 104 kJ/mol. The dissociation of TMV was enthalpy-driven at all temperatures and pressures investigated. Based on these findings, we conclude that the model presented allows accurate predictions of viral dissociation behavior in different experimental conditions. © 2012 American Chemical Society.116511481714828Silva, J.L., Miles, E.W., Weber, G., (1986) Biochemistry, 25, pp. 5780-5786Silva, J.L., Foguel, D., Da Poian, A.T., Prevelige, P.E., (1996) Curr. Opin. Struct. Biol., 6, pp. 166-175Weber, G., Drickamer, H.G., (1983) Q. Rev. Biophys., 16, pp. 89-112Ishimaru, D., Sá-Carvalho, D., Silva, J.L., (2004) Vaccine, 22, pp. 2334-2339Tian, S.M., Ruan, K.C., Qian, J.F., Shao, G.Q., Balny, C., (2000) Eur. J. Biochem., 267, pp. 4486-4494Gaspar, L.P., Mendes, Y.S., Yamamura, A.M.Y., Almeida, L.F.C., Caride, E., Goncalves, R.B., Silva, J.L., Freire, M.S., (2008) J. Virol. Methods, 150, pp. 57-62Oliveira, A.C., Ishimaru, D., Goncalves, R.B., Smith, T.J., Mason, P., Sá-Carvalho, D., Silva, J.L., (1999) Biophys. J., 76, pp. 1270-1279Kingsley, D.H., Hollinian, D.R., Calci, K.R., Chen, H.Q., Flick, G.J., (2007) Appl. Environ. Microbiol., 73, pp. 581-585Bradley, D.W., Hess, R.A., Tao, F., Sciaba-Lentz, L., Remaley, A.T., Laugharn, J.A., Manak, M., (2000) Transfusion (Paris), 40, pp. 193-200Gaspar, L.P., Johnson, J.E., Silva, J.L., Da Poian, A.T., (1997) J. Mol. Biol., 273, pp. 456-466Da Poian, A.T., Oliveira, A.C., Gaspar, L.P., Silva, J.L., Weber, G., (1993) J. Mol. Biol., 231, pp. 999-1008Pontes, L., Cordeiro, Y., Giongo, V., Villas-Boas, M., Barreto, A., Araujo, J.R., Silva, J.L., (2001) J. Mol. Biol., 307, pp. 1171-1179Silva, J.L., Oliveira, A.C., Gomes, A.M.O., Lima, L.M.T.R., Mohana-Borges, R., Pacheco, A.B.F., Foguel, D., (2002) Biochim. Biophys. Acta, Protein Struct. M, 1595, pp. 250-265Bonafe, C.F.S., Glaser, M., Voss, E.W., Weber, G., Silva, J.L., (2000) Biochem. Biophys. Res. Commun., 275, pp. 955-961Jurkiewicz, E., Villas-Boas, M., Silva, J.L., Weber, G., Hunsmann, G., Clegg, R.M., (1995) Proc. Natl. Acad. Sci. U.S.A., 92, pp. 6935-6937Norberto, D.R., Vieira, J.M., Souza, A.R., Bispo, J.A.C., Bonafe, C.F.S., (2012) Open J. Biophys., 2, pp. 4-14Santos, J.L.R., Aparicio, R., Joekes, I., Silva, J.L., Bispo, J.A.C., Bonafe, C.F.S., (2008) Biophys. Chem., 134, pp. 214-224Culver, J.N., (2002) Annu. Rev. Phytopathol., 40, pp. 287-308Pallas, V., Garcia, J.A., (2011) J. Gen. Virol., 92, pp. 2691-2705Klug, A., (1999) Philos. Trans. R. Soc., B, 354, pp. 531-535Namba, K., Pattanayek, R., Stubbs, G., (1989) J. Mol. Biol., 208, pp. 307-325Abel, P.P., Nelson, R.S., De, B., Hoffmann, N., Rogers, S.G., Fraley, R.T., Beachy, R.N., (1986) Science, 232, pp. 738-743Wu, X.J., Beachy, R.N., Wilson, T.M., Shaw, J.G., (1990) Virology, 179, pp. 893-895Bonafe, C.F.S., Vital, C.M.R., Telles, R.C.B., Goncalves, M.C., Matsuura, M.S.A., Pessine, F.B.T., Freitas, D.R.C., Vega, J., (1998) Biochemistry, 37, pp. 11097-11105Santos, J.L.R., Bispo, J.A.C., Landini, G.F., Bonafe, C.F.S., (2004) Biophys. Chem., 111, pp. 53-61Silva, J.L., Villas-Boas, M., Bonafe, C.F.S., Meirelles, N.C., (1989) J. Biol. Chem., 264, pp. 15863-15868Bonafe, C.F.S., Villas-Boas, M., Suarez, M.C., Silva, J.L., (1991) J. Biol. Chem., 266, pp. 13210-13216Bonafe, C.F.S., Araujo, J.R.V., Silva, J.L., (1994) Biochemistry, 33, pp. 2651-2660Orlov, V.N., Arutyunyan, A.M., Kust, S.V., Litmanovich, E.A., Drachev, V.A., Dobrov, E.N., (2001) Biochemistry (Moscow), 66, pp. 154-162Rafikova, E.R., Kurganov, B.I., Arutyunyan, A.M., Kust, S.V., Drachev, V.A., Dobrov, E.N., (2003) Int. J. Biochem. Cell Biol., 35, pp. 1452-1460Asselin, A., Zaitlin, M., (1978) Virology, 91, pp. 173-181Paladini, A.A., Weber, G., (1981) Rev. Sci. Instrum., 52, pp. 419-427Tanford, C., (1961) Physical Chemistry of Macromolecules, , Wiley: New YorkBispo, J.A.C., Bonafe, C.F.S., De Souza, V.B., Silva, J.B.A., Carvalho, G.B.M., (2011) J. Math. Chem., 49, pp. 1976-1995Bispo, J.A.C., Bonafe, C.F.S., Koblitz, M.G.B., Silva, C.G.S., Souza, A.R., (2012) J. Math. Chem., , in pressBaini, R., Langrish, T.A.G., (2007) J. Food Eng., 79, pp. 330-343Silva, J.L., Weber, G., (1993) Annu. Rev. Phys. Chem., 44, pp. 89-113Chalikian, T.V., (2003) Annu. Rev. Biophys. Biomol. Struct., 32, pp. 207-235Bispo, J.A.C., Santos, J.L.R., Landini, G.F., Goncalves, J.M., Bonafe, C.F.S., (2007) Biophys. Chem., 125, pp. 341-349Stites, W.E., (1997) Chem. Rev., 97, pp. 1233-125
Modeling Drying Isotherms Using A Structure Transition Model
No full textDrying introduces structural changes in the target material that modify its interaction with water. In this work, we developed a model based on star fruit drying that considered two forms of interaction with water. This model provided a very good fit to the experimental data and was applicable to drying of other products such as apple, barley, and coffee. This model yielded better fits for data reported in the literature than other models. These findings suggest that the model is applicable to a wide range of systems. © 2013 Copyright Taylor and Francis Group, LLC.31910081019Fellows, P., (2000) Food Processing Technology Principles and Practice, 2nd Ed, , CRC Press, Boca Raton, FLMao, S.W., Srzednicki, G., Driscoll, R.H., Modeling of drying of selected varieties of australian peanuts (2012) Drying Technology, 30 (16), pp. 1890-1895Neto, M.M., Robl, F., Netto, J.C., Intoxication by star fruit (Averrhoa carambola) in six dialysis patients? (Preliminary report) (1998) Nephrology Dialisis Transplantation, 13 (3), pp. 570-572Chang, J.M., Hwang, S.J., Kuo, H.T., Tsai, J.C., Guh, J.Y., Chen, H.C., Tsai, J.H., Lai, Y.H., Fatal outcome after ingestion of star fruit (Averrhoa carambola) in uremic patients (2000) American Journal of Kidney Diseases, 35 (2), pp. 189-193Provasi, M., Oliveira, C.E., Martino, M.C., Pessini, L.G., Bazotte, R.B., Cortez, D.A.G., Avaliação da toxicidade e do potencial antihiperglicemiante da Averrhoa carambola L. (Oxalidaceae) (2001) Acta Scientiarum, 23 (3), pp. 665-669Baldini, V.L.S., Draeta, I.S., Nomura, E.H., Avaliação bioquímica de carambola (Averrhoa carambola, L.) (1982) Coletânea do ITAL, 12, pp. 283-291Bispo, J.A.C., Bonafe, C.F.S., de Souza, V.B., Silva, J.B.A., Carvalho, G.B.M., Extending the kinetic solution of the classic Michaelis-Menten model of enzyme action (2011) Journal of Mathematical Chemistry, 49 (9), pp. 1976-1995Bispo, J.A.C., Bonafe, C.F.S., Koblitz, M.G.B., Silva, C.G.S., Souza, A.R., Substrate and enzyme concentration dependence of the Henri-Michaelis-Menten model probed by numerical simulation (2013) Journal of Mathematical Chemistry, 51, pp. 144-152Page, G., (1949) Factors Influencing the Maximum Rates of Air-Drying Shelled Corn in Thin Layers, , Purdue University, Lafayatte, INKarathanos, V.T., Determination of water content of dried fruits by drying kinetics (1999) Journal of Food Engineering, 39 (4), pp. 337-344Verma, L.R., Bucklin, R.A., Endan, J.B., Wratten, F.T., Effects of drying air parameters on rice drying models (1985) Transactions of the ASAE, 28 (1), pp. 296-301Chen, X.D., Lin, S.X.Q., Air drying of milk droplet under constant and time-dependent conditions (2005) AIChE Journal, 51 (6), pp. 1790-1799Putranto, A., Chen, X.D., Roasting of barley and coffee modeled using the lumped-reaction engineering approach (L-REA) (2012) Drying Technology, 30 (5), pp. 475-483Lin, S.X.Q., Chen, X.D., A model for drying of an aqueous lactose droplet using the reaction engineering approach (2006) Drying Technology, 24 (11), pp. 1329-1334Putranto, A., Chen, X.D., Modeling intermittent drying of wood under rapidly varying temperature and humidity conditions with the lumped reaction engineering approach (L-REA) (2012) Drying Technology, 30 (14), pp. 1658-1665O'Callagh, J.R., Menzies, D.J., Bailey, P.H., Digital simulation of agricultural drier performance (1971) Journal of Agricultural Engineering Research, 16 (3), pp. 223-244Baini, R., Langrish, T.A.G., Choosing an appropriate drying model for intermittent and continuous drying of bananas (2007) Journal of Food Engineering, 79 (1), pp. 330-343Xu, G., Weber, G., Dynamics and time-averaged chemical potential of proteins: importance in oligomer association (1982) Proceedings of the National Academy of Sciences of the United States of America, 79 (17), pp. 5268-5271Weber, G., Phenomenological description of the association of protein subunits subjected to conformational drift. Effects of dilution and of hydrostatic pressure (1986) Biochemistry, 25 (12), pp. 3626-3631Weber, G., (1992) Protein Interactions, , Chapman & Hall, New YorkBispo, J.A.C., Bonafe, C.F.S., Joekes, I., Martinez, E.A., Carvalho, G.B.M., Norberto, D.R., Entropy and volume change of dissociation in tobacco mosaic virus probed by high pressure (2012) Journal of Physical Chemistry B, 166, pp. 14817-14828Velic, D., Planinic, M., Tomas, S., Bilic, M., Influence of airflow velocity on kinetics of convection apple drying (2004) Journal of Food Engineering, 64 (1), pp. 97-102Henderson, S.M., Pabis, S., Grain drying theory: IV. The effect of air flow rate on the drying index (1962) Journal of Agricultural Engineering Research, 7 (1), pp. 85-89Claussen, I.C., Ustad, T.S., Strommen, I., Waide, P.M., Atmospheric freeze drying-A review (2007) Drying Technology, 25 (4-6), pp. 947-957Wolff, E., Gibert, H., Part 2. Modeling drying kinetics using adsorption isotherms (1990) Drying Technology, 8 (2), pp. 405-428. , Atmosphericfreeze-dryingJangam, S.V., Joshi, V.S., Mujumdar, A.S., Thorat, B.N., Studies on dehydration of sapota (Achras zapota) (2008) Drying Technology, 26 (3), pp. 369-377Sharaf-Eldeen, Y.I., Blaisdell, J.L., Hamdy, M.Y., A model for ear corn drying (1980) Transactions of the ASAE, 23 (5), pp. 1261-1265Monod, J., Wyman, J., Changeux, J.P., On the nature of allosteric transitions: A plausible model (1965) Journal of Molecular Biology, 12 (1), pp. 88-118Akanbi, C.T., Adeyemi, R.S., Ojo, A., Drying characteristics and sorption isotherm of tomato slices (2006) Journal of Food Engineering, 73 (2), pp. 157-163Fabra, M.J., Talens, P., Moraga, G., Martinez-Navarrete, N., Sorption isotherm and state diagram of grapefruit as a tool to improve product processing and stability (2009) Journal of Food Engineering, 93 (1), pp. 52-5
A Comparison Of Drying Kinetics Based On The Degree Of Hydration And Moisture Ratio
No full textThe most widely used experimental parameter for modeling drying processes is the loss of sample mass, which is converted to the ratio between the water content at time t and the initial water content (moisture ratio, MR). Here we studied the drying of pineapple fruits and converted the experimental data for loss of mass to degree of hydration αH(t), which corresponds to the ratio between the water content and the sample mass. This approach allowed us to propose a thermodynamic model for the drying process. The results for the minimum local Gibbs free energy showed that for a degree of hydration of 0.1 the process was more spontaneous at 110°C and a drying time of 90min. However, the entropy of the process was maximal at 70°C and a drying time of 163min. The optimization of drying process and quality of the dried product should be better controlled throughout such this thermodynamic monitoring. The treatment of the data applying the MR approach in the structure transition model produced reasonable fitting, but with several limitations related to the thermodynamic derivation.601192198Akanbi, C.T., Adeyemi, R.S., Ojo, A., Drying characteristics and sorption isotherm of tomato slices (2006) Journal of Food Engineering, 73 (2), pp. 157-163Baini, R., Langrish, T.A.G., Choosing an appropriate drying model for intermittent and continuous drying of bananas (2007) Journal of Food Engineering, 79 (1), pp. 330-343. , (This article is of particular importance because of the comparative analysis of different methods used to characterize drying in intermittent and continuous processes.)Bispo, J.A.C., Bonafe, C.F.S., Joekes, I., Martinez, E.A., Carvalho, G.B.M., Norberto, D.R., Entropy and volume change of dissociation in tobacco mosaic virus probed by high pressure (2012) Journal of Physical Chemistry B, 166 (51), pp. 14817-14828Bispo, J.A.C., Bonafe, C.F.S., Xavier, D., Brandao, T., Rodrigues, C., Oliveira, M.G.A., Optimizing drying processes by using a structural transition model and entropy change maximization (2014) Drying Technology, 32 (8), pp. 910-918. , (This work shows that optimization of the energy expended during drying, as well as physical properties such as composition, hydration and texture, should be reached at optimal conditions by minimizing the Gibbs free energy of water release or, for entropy-driven processes, by maximizing the entropy of water release. The applicability of this approach in industrial processes could be very relevant.)Bispo, J.A.C., Silva, C.M.R., Bonafe, C.F.S., Assis, D.J., Modeling drying isotherms using a structure transition model (2013) Drying Technology, 31 (9), pp. 1008-1019. , (This work provides the first description of the use of the concept of extent of reaction to characterize drying processes based on structural transition. This approach allows a non-empirical description of drying and permits consideration of the energy surfaces of water release from the samples during drying.)Chen, X.D., Lin, S.X.Q., Air drying of milk droplet under constant and time-dependent conditions (2005) AIChE Journal, 51 (6), pp. 1790-1799Erenturk, S., Gulaboglu, M.S., Gultekin, S., The thin-layer drying characteristics of rosehip (2004) Biosystems Engineering, 89 (2), pp. 159-166Fabra, M.J., Talens, P., Moraga, G., Martinez-Navarrete, N., Sorption isotherm and state diagram of grapefruit as a tool to improve product processing and stability (2009) Journal of Food Engineering, 93 (1), pp. 52-58Fellows, P., (2000) Food processing technology principles and practice, , CRC Press, Boca Raton and CambridgeHenderson, S.M., Pabis, S., Grain drying theory: IV. The effect of air flow rate on the drying index (1962) Journal of Agricultural Engineering Research, 7 (1), pp. 85-89Huang, L.L., Zhang, M., Wang, L.P., Mujumdar, A.S., Sun, D.F., Influence of combination drying methods on composition, texture, aroma and microstructure of apple slices (2012) LWT - Food Science and Technology, 47 (1), pp. 183-188. , (This article uses the combined effects of different methods to describe aspects not previously explored in the field of drying while at the same time providing an analysis of many parameters relevant to the development of new products and processes.)Lin, S.X.Q., Chen, X.D., Amodel for drying of an aqueous lactose droplet using the reaction engineering approach (2006) Drying Technology, 24 (11), pp. 1329-1334Madamba, P.S., Driscoll, R.H., Buckle, K.A., The thin-layer drying characteristics of garlic slices (1996) Journal of Food Engineering, 29 (1), pp. 75-97Mazza, G., Lemaguer, M., Dehydration of onion. Some theoretical and practical considerations (1980) Journal of Food Technology, 15 (2), pp. 181-194Monod, J., Wyman, J., Changeux, J.P., On the nature of allosteric transitions: a plausible model (1965) Journal of Molecular Biology, 12 (1), pp. 88-118Page, G., (1949) Factors influencing the maximum rates of air-drying shelled corn in thin layers, , Purdue University, Lafayatte, (This work is one of the most important studies in the field of drying because its publication stimulated considerable interest in the mathematical modelling of drying. This interest in turn led to other proposals that sought to optimize and develop new products based on the drying parameters provided by various models.)Putranto, A., Chen, X.D., Roasting of barley and coffee modeled using the lumped-reaction engineering approach (L-REA) (2012) Drying Technology, 30 (5), pp. 475-483Sharaf-Eldeen, Y.I., Blaisdell, J.L., Hamdy, M.Y., Amodel for ear corn drying (1980) Transactions of the ASAE, 23 (5), pp. 1261-1265Silva, W.P., Silva, C.M.D.P.S., Lins, M.A.A., Gomes, J.P., Osmotic dehydration of pineapple (Ananas comosus) pieces in cubical shape described by diffusion models (2014) LWT - Food Science and Technology, 55 (1), pp. 1-8Verma, L.R., Bucklin, R.A., Endan, J.B., Wratten, F.T., Effects of drying air parameters on rice drying models (1985) Transactions of the ASAE, 28 (1), pp. 296-301Wang, C.Y., Singh, R.P., (1978) Use of variable equilibrium moisture content in modelling rice drying, , ASAE, Paper 78-6505, ASAE, St. Joseph-MIWeber, G., Phenomenological description of the association of protein subunits subjected to conformational drift. Effects of dilution and of hydrostatic pressure (1986) Biochemistry, 25 (12), pp. 3626-3631Whitaker, T.B., Barre, H.J., Hamdy, M.Y., Theoretical and experimental studies of diffusion in spherical bodies with a variable diffusion coefficient (1969) Transactions of the ASAE, 12 (5), pp. 668-672Yemmireddy, V.K., Chinnan, M.S., Kerr, W.L., Hung, Y.C., Effect of drying method on drying time and physico-chemical properties of dried rabbiteye blueberries (2013) LWT - Food Science and Technology, 50 (2), pp. 739-745Young, J.H., Simultaneous heat and mass transfer in a porous solid hygroscopic solids (1969) Transactions of the ASAE, 12 (5), pp. 720-72
Substrate And Enzyme Concentration Dependence Of The Henri-michaelis-menten Model Probed By Numerical Simulation
No full textThe use of the classic Henry-Michaelis-Menten (HMM) model (or simply, Michaelis-Menten model) to study the substrate and enzyme concentration dependence of enzyme catalysis is a very important step in understanding many biochemical processes, including microbial growth. Although the HMM model has been extensively studied, the conditions in which the substrate concentration is not in excess have still not been adequately defined mathematically. This lack of definition occurs despite at the cellular and molecular levels most systems generally do not operate in a state of substrate excess. In the present work, we describe an approach for studying enzyme reactions in which substrate concentrations are not in excess. Our results show that the use of extent of reactions and numerical simulation of the velocities of reaction provides an important advance in this field and furnishes results not obtained in previous studies involving these aspects. This approach, in association with knowledge of the rate constants, provides a direct and easy means of examining the single substrate-enzyme profile during product formation at any enzyme-substrate ratio. This approach is more direct than previous models that required the use of empirical equations with arbitrary constants. © 2012 Springer Science+Business Media, LLC.511144152Michaelis, L., Menten, M.L., (1913) Biochem. Z., 49, p. 333Briggs, G.E., Haldane, J.B., (1925) Biochem. J., 19, p. 338Bispo, J.A.C., Bonafe, C.F.S., de Souza, V.B., Silva, J.B.A., Carvalho, G.B.M., (2011) J. Math. Chem., 49, p. 1976Bajzer, Z., Strehler, E.E., (2012) Biochem. Biophys. Res. Commun., 417, p. 982Kargi, F., (2009) Biochem. Biophys. Res. Commun., 382, p. 157Schnell, S., Mendoza, C., (1997) J. Theor. Biol., 187, p. 207Bersani, A.M., Dell'Acqua, G., (2011) Math. Methods Appl. Sci., 34, p. 1954Tzafriri, A.R., (2003) Bull. Math. Biol., 65, p. 1111Schnell, S., Maini, P.K., (2000) Bull. Math. Biol., 62, p. 483Schnell, S., Maini, P.K., (2002) Math. Comput. Model., 35, p. 137Chapra, S.C., Canale, R.P., (2010) Numerical Methods for Engineers, , Maidenherd: McGraw-HillBoyce, W.E., Diprima, R.C., (2009) Elementary Differential Equations and Boundary Value Problems, , London: Wile
Potentiation Of High Hydrostatic Pressure Inactivation Of Mycobacterium By Combination With Physical And Chemical Conditions
No full textMycobacterium abscessus is an important hospital-acquired pathogen involved in infections associated with medical, surgical, and biopharmaceutical materials. In this work, we investigated the pressure-induced inactivation of two strains [2544 and American Type Culture Collection (ATCC) 19977] of M. abscessus in combination with different temperatures and pH conditions. For strain 2544, exposure to 250 MPa for 90 min did not significantly inactivate the bacteria at 20 C, whereas at -15 C, there was complete inactivation. Exposure to 250 MPa at ≥60 C caused rapid inactivation, with no viable bacteria after 45 min. With 45 min of exposure, there were no viable bacteria at any temperature when a higher pressure (350 MPa) was used. Extremes of pH (4 or 9) also markedly enhanced the pressure-induced inactivation of bacteria at 250 MPa, with complete inactivation after 45 min. In comparison, exposure of this strain to the disinfecting agent glutaraldehyde (0.5 %) resulted in total inactivation within 5 min. Strain 19977 was more sensitive to high pressure but less sensitive to glutaraldehyde than strain 2544. These results indicate that high hydrostatic pressure in combination with other physical parameters may be useful in reducing the mycobacterial contamination of medical materials and pharmaceuticals that are sensitive to autoclaving. © 2013 Springer-Verlag Berlin Heidelberg.971674177425Bello, T., Rivera-Olivero, I.A., De Waard, J.H., Inactivation of mycobacteria by disinfectants with a tuberculocidal label (2006) Enfermedades Infecciosas y Microbiologia Clinica, 24 (5), pp. 319-321Bigata, X., Ribera, M., Bielsa, I., Ferrandiz, C., Adverse granulomatous reaction after cosmetic dermal silicone injection (2001) Dermatologic Surgery, 27 (2), pp. 198-200. , DOI 10.1046/j.1524-4725.2001.00020.xBispo, J.A.C., Santos, J.L.R., Landini, G.F., Goncalves, J.M., Bonafe, C.F.S., PH dependence of the dissociation of multimeric hemoglobin probed by high hydrostatic pressure (2007) Biophysical Chemistry, 125 (2-3), pp. 341-349. , DOI 10.1016/j.bpc.2006.09.009, PII S0301462206002742Bonafe, C.F.S., Glaser, M., Voss, E.W., Weber, G., Silva, J.L., Virus inactivation by anilinonaphthalene sulfonate compounds and comparison with other ligands (2000) Biochem Biophys Res Commun, 275, pp. 955-961. , 10.1006/bbrc.2000.3402 10973827 10.1006/bbrc.2000.3402 1:CAS:528:DC%2BD3cXmtFGltr8%3DBonafe, C.F.S., Vital, C.M.R., Telles, R.C.B., Goncalves, M.C., Matsuura, M.S.A., Pessine, F.B.T., Freitas, D.R.C., Vega, J., Tobacco mosaic virus disassembly by high hydrostatic pressure in combination with urea and low temperature (1998) Biochemistry, 37 (31), pp. 11097-11105. , DOI 10.1021/bi980349n, PII S0006296098003493Brown-Elliott, B.A., Wallace Jr., R.J., Clinical and taxonomic status of pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria (2002) Clinical Microbiology Reviews, 15 (4), pp. 716-746. , DOI 10.1128/CMR.15.4.716-746.2002Cooke, R.P.D., Goddard, S.V., Whymant-Morris, A., Sherwood, J., Chatterly, R., An evaluation of Cidex OPA (0.55% ortho-phthalaldehyde) as an alternative to 2% glutaraldehyde for high-level disinfection of endoscopes (2003) Journal of Hospital Infection, 54 (3), pp. 226-231. , DOI 10.1016/S0195-6701(03)00040-9, PII S0195670103000409Duraes-Carvalho, R., Souza, A.R., Martins, L.M., Sprogis, A.C., Bispo, J.A.C., Bonafe, C.F.S., Yano, T., Effect of high hydrostatic pressure on Aeromonas hydrophila AH 191 growth in milk (2012) J Food Sci, 77, pp. 417-M424. , 10.1111/j.1750-3841.2012.02819.x 22860590 10.1111/j.1750-3841.2012.02819. x 1:CAS:528:DC%2BC38XhsFKku7bKFonberg-Broczek, M., Windyga, B., Szczawinski, J., Szczawinska, M., Pietrzak, D., Prestamo, G., High pressure processing for food safety (2005) Acta Biochimica Polonica, 52 (3), pp. 721-724Fox, L.P., Geyer, A.S., Husain, S., Della-Latta, P., Grossman, M.E., Mycobacterium abscessus cellulitis and multifocal abscesses of the breasts in a transsexual from illicit intramammary injections of silicone (2004) Journal of the American Academy of Dermatology, 50 (3), pp. 450-454. , DOI 10.1016/j.jaad.2003.09.008Gorman, S.P., Scott, E.M., Russell, A.D., Antimicrobial activity, uses and mechanism of action of glutaraldehyde (1980) Journal of Applied Bacteriology, 48 (2), pp. 161-190Griffith, D.E., Emergence of nontuberculous mycobacteria as pathogens in cystic fibrosis (2003) American Journal of Respiratory and Critical Care Medicine, 167 (6), pp. 810-812. , DOI 10.1164/rccm.2301001Hashizume, C., Kimura, K., Hayashi, R., Kinetic analysis of yeast inactivation by high pressure treatment at low temperatures (1995) Biosci Biotechnol Biochem, 59, pp. 1455-1458. , 7549097 10.1271/bbb.59.1455 1:CAS:528:DyaK2MXnvFKnu7w%3DKatoch, V.M., Infections due to non-tuberculous mycobacteria (NTM) (2004) Indian Journal of Medical Research, 120 (4), pp. 290-304Le Dantec, C., Duguet, J.-P., Montiel, A., Dumoutier, N., Dubrou, S., Vincent, V., Occurrence of mycobacteria in water treatment lines and in water distribution systems (2002) Applied and Environmental Microbiology, 68 (11), pp. 5318-5325Mackey, B.M., Forestiere, K., Isaacs, N.S., Stenning, R., Brooker, B., The effect of high hydrostatic pressure on Salmonella thompson and Listeria monocytogenes examined by electron microscopy (1994) Letters in Applied Microbiology, 19 (6), pp. 429-432Masson, P., Tonello, C., Balny, C., High-pressure biotechnology in medicine and pharmaceutical science (2001) Journal of Biomedicine and Biotechnology, 2001 (2), pp. 85-88. , DOI 10.1155/S1110724301000158, PII S1110724301000158McGaw, L.J., Lall, N., Hlokwe, T.M., Michel, A.L., Meyer, J.J.M., Eloff, J.N., Purified compounds and extracts from Euclea species with antimycobacterial activity against Mycobacterium bovis and fast-growing mycobacteria (2008) Biological and Pharmaceutical Bulletin, 31 (7), pp. 1429-1433. , http://www.jstage.jst.go.jp/article/bpb/31/7/1429/_pdf, DOI 10.1248/bpb.31.1429Medjahed, H., Gaillard, J.L., Reyrat, J.M., Mycobacterium abscessus: A new player in the mycobacterial field (2010) Trends Microbiol, 18, pp. 117-123. , 10.1016/j.tim.2009.12.007 20060723 10.1016/j.tim.2009.12.007 1:CAS:528:DC%2BC3cXjtVCksbk%3DMolina-Gutierrez, A., Stippl, V., Delgado, A., Ganzle, M.G., Vogel, R.F., In situ determination of the intracellular pH of Lactococcus lactis and Lactobacillus plantarum during pressure treatment (2002) Applied and Environmental Microbiology, 68 (9), pp. 4399-4406. , DOI 10.1128/AEM.68.9.4399-4406.2002Moussa, M., Perrier-Cornet, J.M., Gervais, P., Synergistic and antagonistic effects of combined subzero temperature and high pressure on inactivation of Escherichia coli (2006) Appl Environ Microbiol, 72, pp. 150-156. , 10.1128/Aem.72.1.150-156.2006 16391037 10.1128/AEM.72.1.150-156.2006 1:CAS:528:DC%2BD28XmtFamsA%3D%3DMurillo, J., Torres, M., Bofill, L., Rios-Fabra, A., Irausquin, E., Isturiz, R., Guzman, M., Cordido, M., Skin and wound infection by rapidly growing mycobacteria. An unexpected complication of liposuction and liposculpture (2000) Arch Dermatol, 136, pp. 1347-1352. , 11074697 10.1001/archderm.136.11.1347 1:STN:280:DC%2BD3M%2FjtlCjtA%3D%3DNeuman, R.C., Kauzmann, W., Zipp, A., Pressure dependence of weak acid ionization in aqueous buffers (1973) J Phys Chem, 77, pp. 2687-2691. , 10.1021/j100640a025 1:CAS:528:DyaE3sXlsFSjtbs%3DPetrini, B., Mycobacterium abscessus: An emerging rapid-growing potential pathogen (2006) APMIS, 114 (5), pp. 319-328. , DOI 10.1111/j.1600-0463.2006.apm-390.xPonce, E., Pla, R., Sendra, E., Guamis, B., Mor-Mur, M., Destruction of Salmonella enteritidis inoculated in liquid whole egg by high hydrostatic pressure: Comparative study in selective and non-selective media (1999) Food Microbiology, 16 (4), pp. 357-365. , DOI 10.1006/fmic.1998.0248Portaels, F., Pattyn, S.R., Growth of mycobacteria in relation to the pH of the medium (1982) Annales de Microbiologie, B133 (2), pp. 213-221Rikimaru, T., Kondo, M., Kondo, S., Oizumi, K., Efficacy of common antiseptics against mycobacteria (2000) International Journal of Tuberculosis and Lung Disease, 4 (6), pp. 570-576Ripoll, F., Pasek, S., Schenowitz, C., Dossat, C., Barbe, V., Rottman, M., Macheras, E., Gaillard, J.L., Non mycobacterial virulence genes in the genome of the emerging pathogen Mycobacterium abscessus (2009) PLoS One, 4, p. 5660. , 10.1371/Journal.Pone.0005660 19543527 10.1371/journal.pone.0005660Ritz, M., Tholozan, J.L., Federighi, M., Pilet, M.F., Physiological damages of Listeria monocytogenes treated by high hydrostatic pressure (2002) International Journal of Food Microbiology, 79 (1-2), pp. 47-53. , DOI 10.1016/S0168-1605(02)00178-2, PII S0168160502001782Rivalain, N., Roquain, J., Demazeau, G., Development of high hydrostatic pressure in biosciences: Pressure effect on biological structures and potential applications in biotechnologies (2010) Biotechnol Adv, 28, pp. 659-672. , 10.1016/j.biotechadv.2010.04.001 20398747 10.1016/j.biotechadv.2010.04. 001 1:CAS:528:DC%2BC3cXht1Wltr7LRutala, W.A., Cole, E.C., Wannamaker, N.S., Weber, D.J., Inactivation of Mycobacterium tuberculosis and Mycobacterium bovis by 14 hospital disinfectants (1991) Am J Med, 91, pp. 267S-271S. , 1928175 10.1016/0002-9343(91)90380-G 1:STN:280:DyaK38%2Fis1Wqsg%3D%3DRutala, W.A., Gergen, M.F., Weber, D.J., Comparative evaluation of the sporicidal activity of new low- temperature sterilization technologies: Ethylene oxide, 2 plasma sterilization systems, and liquid peracetic acid (1998) American Journal of Infection Control, 26 (4), pp. 393-398Sale, A.J., Gould, G.W., Hamilton, W.A., Inactivation of bacterial spores by hydrostatic pressure (1970) J Gen Microbiol, 60, pp. 323-334. , 4922567 10.1099/00221287-60-3-323 1:STN:280:DyaE3M%2FlvVyisQ%3D%3DSantos, J.L.R., Aparicio, R., Joekes, I., Silva, J.L., Bispo, J.A.C., Bonafe, C.F.S., Different urea stoichiometries between the dissociation and denaturation of tobacco mosaic virus as probed by hydrostatic pressure (2008) Biophys Chem, 134, pp. 214-224. , 10.1016/j.bipc.2008.02.010 18367310 10.1016/j.bpc.2008.02.010 1:CAS:528:DC%2BD1cXksVahtbc%3DSantos, J.L.R., Bispo, J.A.C., Landini, G.F., Bonafe, C.F.S., Proton dependence of tobacco mosaic virus dissociation by pressure (2004) Biophysical Chemistry, 111 (1), pp. 53-61. , DOI 10.1016/j.bpc.2004.04.003, PII S0301462204001139Silva, J.L., Villas-Boas, M., Bonafe, C.F.S., Meirelles, N.C., Anomalous pressure dissociation of large protein aggregates. Lack of concentration dependence and irreversibility at extreme degrees of dissociation of extracellular hemoglobin (1989) Journal of Biological Chemistry, 264 (27), pp. 15863-15868Sohn, H., Kim, H.J., Kim, J.M., Kwon, O.J., Koh, W.J., Shin, S.J., High virulent clinical isolates of Mycobacterium abscessus from patients with the upper lobe fibrocavitary form of pulmonary disease (2009) Microb Pathog, 47, pp. 321-328. , 10.1016/j.micpath.2009.09.010 19800962 10.1016/j.micpath.2009.09.010 1:CAS:528:DC%2BD1MXhsVaks7vPSpilimbergo, S., Elvassore, N., Bertucco, A., Microbial inactivation by high-pressure (2002) J Supercrit Fluids, 22, pp. 55-63. , 10.1016/S0896-8446(01)00106-1 1:CAS:528:DC%2BD3MXpt1aitrg%3DStewart, C.M., Jewett, F.F., Dunne, C.P., Hoover, D.G., Effect of concurrent high hydrostatic pressure, acidity and heat on the injury and destruction of Listeria monocytogenes (1997) Journal of Food Safety, 17 (1), pp. 23-36Sugimoto, H., Ito, M., Hatano, M., Nakanishi, Y., Maruyama, Y., Yoshizaki, T., A case of chronic otitis media caused by Mycobacterium abscessus (2010) Auris Nasus Larynx, 37, pp. 636-639. , 10.1016/j.anl.2010.01.010 20206453 10.1016/j.anl.2010.01.010Takahashi, K., Sterilization of microorganisms by hydrostatic pressure at low temperature (1992) High Press Biotecnol, 224, pp. 303-307Tholozan, J.-L., Ritz, M., Jugiau, F., Federighi, M., Tissier, J.P., Physiological effects of high hydrostatic pressure treatments on Listeria monocytogenes and Salmonella typhimurium (2000) Journal of Applied Microbiology, 88 (2), pp. 202-212. , DOI 10.1046/j.1365-2672.2000.00917.
Different Urea Stoichiometries Between The Dissociation And Denaturation Of Tobacco Mosaic Virus As Probed By Hydrostatic Pressure
No full textViruses are very efficient self-assembly structures, but little is understood about the thermodynamics governing their directed assembly. At higher levels of pressure or when pressure is combined with urea, denaturation occurs. For a better understanding of such processes, we investigated the apparent thermodynamic parameters of dissociation and denaturation by assuming a steady-state condition. These processes can be measured considering the decrease of light scattering of a viral solution due to the dissociation process, and the red shift of the fluorescence emission spectra, that occurs with the denaturation process. We determined the apparent urea stoichiometry considering the equilibrium reaction of TMV dissociation and subunit denaturation, which furnished, respectively, 1.53 and 11.1 mol of urea/mol of TMV subunit. The denaturation and dissociation conditions were arrived in a near reversible pathway, allowing the determination of thermodynamic parameters. Gel filtration HPLC, electron microscopy and circular dichroism confirmed the dissociation and denaturation processes. Based on spectroscopic results from earlier papers, the calculation of the apparent urea stoichiometry of dissociation and denaturation of several other viruses resulted in similar values, suggesting a similar virus-urea interaction among these systems. © 2008 Elsevier B.V. All rights reserved.1343214224Silva, J.L., Weber, G., Pressure stability of proteins (1993) Annu. Rev. Phys. Chem., 44, pp. 89-113Weber, G., Drickamer, H.G., The effect of high pressure upon proteins and other biomolecules (1983) Q. Rev. Biophys., 16, pp. 89-112Weber, G., Phenomenological description of the association of protein subunits subjected to conformational drift. Effects of dilution and of hydrostatic pressure (1986) Biochemistry, 25, pp. 3626-3631Silva, J.L., Oliveira, A.C., Gomes, A.M.O., Lima, L.M.T.R., Mohana-Borges, R., Pacheco, A.B.F., Foguel, D., Pressure induces folding intermediates that are crucial for protein-DNA recognition and virus assembly (2002) Biochim. Biophys. Acta, 1595, pp. 250-265Balny, C., What lies in the future of high-pressure bioscience? (2006) Biochim. Biophys. Acta, 1764, pp. 632-639Da Poian, A.T., Oliveira, A.C., Gaspar, L.P., Silva, J.L., Weber, G., Reversible pressure dissociation of R17 bacteriophage. The physical individuality of virus particles (1993) J. Mol. Biol., 231, pp. 999-1008Da Poian, A.T., Johnson, J.E., Silva, J.L., Differences in pressure stability of the three components of cowpea mosaic virus: implications for virus assembly and disassembly (1994) Biochemistry, 33, pp. 8339-8346Gaspar, L.P., Johnson, J.E., Silva, J.L., Da Poian, A.T., Partially folded states of the capsid protein of cowpea severe mosaic virus in the disassembly pathway (1997) J. Mol. Biol., 273, pp. 456-466Bonafe, C.F.S., Vital, C.M.R., Telles, R.C.B., Gonçalves, M.C., Matsuura, M.S.A., Pessine, F.B., Freitas, D.R.C., Vega, J., Tobacco mosaic virus disassembly by high hydrostatic pressure in combination with urea and low temperature (1998) Biochemistry, 37, pp. 11097-11105Oliveira, A.C., Ishimaru, D., Goncalves, R.B., Smith, T.J., Mason, P., Sa-Carvalho, D., Silva, J.L., Low temperature and pressure stability of picornaviruses: implications for virus uncoating (1999) Biophys. J., 76, pp. 1270-1279Sousa, P., Tuma, R., Prevelige, P.E., Silva, J.L., Foguel, D., Cavity defects in the procapsid of bacteriophage P22 and the mechanism of capsid maturation (1999) J. Mol. Biol., 287, pp. 527-538Oliveira, A.C., Gomes, A.M., Almeida, F.C., Mohana-Borges, R., Valente, A.P., Reddy, V.S., Johnson, J.E., Silva, J.L., Virus maturation targets the protein capsid to concerted disassembly and unfolding (2000) J. Biol. Chem., 275, pp. 16037-16043Gaspar, L.P., Terezan, A.F., Pinheiro, A.S., Foguel, D., Rebello, M.A., Silva, J.L., The metastable state of nucleocapsids of enveloped viruses as probed by high hydrostatic pressure (2001) J. Biol. Chem., 276, pp. 7415-7421Pontes, L., Cordeiro, Y., Giongo, V., Villas-Boas, M., Barreto, A., Araujo, J.R., Silva, J.L., Pressure-induced formation of inactive triple-shelled rotavirus particles is associated with changes in the spike protein VP4 (2001) J. Mol. Biol., 307, pp. 1171-1179Schwarcz, W.D., Barroso, S.P.C., Gomes, A.M.O., Johnson, J.E., Schneemann, A., Oliveira, A.C., Silva, J.L., Virus stability and protein-nucleic acid interaction as studied by high-pressure effects on nodaviruses (2004) Cell. Mol. Biol., 50, pp. 419-427Lima, S.M.B., Vaz, A.C.Q., Souza, T.L.F., Peabody, D.S., Silva, J.L., Oliveira, A.C., Dissecting the role of protein-protein and protein-nucleic acid interactions in MS2 bacteriophage stability (2006) FEBS J., 273, pp. 1463-1475Bonafe, C.F.S., Glaser, M., Voss, E.W., Weber, G., Silva, J.L., Virus inactivation by anilinonaphthalene sulfonate compounds and comparison with other ligands (2000) Biochem. Biophys. Res. Commun., 275, pp. 955-961Ishimaru, D., S-Carvalho, D., Silva, J.L., Pressure-inactivated FMDV: a potential vaccine (2004) Vaccine, 22, pp. 2334-2339Goelet, P., Lomonossoff, G.P., Butler, P.J., Akam, M.E., Gait, M.J., Karn, J., Nucleotide sequence of tobacco mosaic virus RNA (1982) Proc. Natl. Acad. Sci. U. S. A., 79, pp. 5818-5822Stanley, W.M., Lauffer, M.A., Disintegration of tobacco mosaic virus in urea solution (1939) Science, 89, pp. 345-347Blowers, L.E., Wilson, T.M.A., The effect of urea on tobacco mosaic virus-polarity of disassembly (1982) J. Gen. Virol., 61, pp. 137-141Bispo, J.A.C., Santos, J.L.R., Landini, G.F., Goncalves, J.M., Bonafe, C.F.S., pH dependence of the dissociation of multimeric hemoglobin probed by high hydrostatic pressure (2007) Biophys. Chemist., 125, pp. 341-349Santos, J.L.R., Bispo, J.A.C., Landini, G.F., Bonafe, C.F.S., Proton dependence of tobacco mosaic virus dissociation by pressure (2004) Biophys. Chemist., 111, pp. 53-61Asselin, A., Zaitlin, M., Characterization of a second protein associated with virions of tobacco mosaic virus (1978) Virology, 91, pp. 173-181Paladini, A.A., Weber, G., Absolute measurements of fluorescence polarization at high pressures (1981) Rev. Sci. Instrum., 52, pp. 419-427Tanford, C., (1961) Physical Chemistry of Macromolecules, , WileySilva, J.L., Villas-Boas, M., Bonafe, C.F.S., Meirelles, N.C., Anomalous pressure dissociation of large protein aggregates. Lack of concentration dependence and irreversibility at extreme degrees of dissociation of extracellular hemoglobin (1989) J. Biol. Chem., 264, pp. 15863-15868Vivian, J.T., Callis, P.R., Mechanisms of tryptophan fluorescence shifts in proteins (2001) Biophys. J., 80, pp. 2093-2109Winn, M., Dodson, E.J., Ralph, A., Collaborative computational project, number 4: providing programs for protein crystallography (1997) Method. Enzymol., 277, pp. 620-633Lavenga, B.H., (1978) Thermodynamics of Irreversible Processes, , The Macmillan Press Ltd., LondonScholtz, J.M., Barrick, D., York, E.J., Stewart, J.M., Baldwin, R.L., Urea unfolding of peptide helices as a model for interpreting protein unfolding (1995) Proc. Natl. Acad. Sci. U. S. A., 92, pp. 185-189Vanzi, F., Madan, B., Sharp, K., Effect of the protein denaturants urea and guanidinium on water structure: A structural and thermodynamic study (1998) J. Am. Chem. Soc., 120, pp. 10748-10753Omta, A.W., Kropman, M.F., Woutersen, S., Bakker, H.J., Negligible effect of ions on the hydrogen-bond structure in liquid water (2003) Science, 301, pp. 347-349Batchelor, J.D., Olteanu, A., Tripathy, A., Pielak, G.J., Impact of protein denaturants and stabilizers on water structure (2004) J. Am. Chem. Soc., 126, pp. 1958-1961Robinson, C.R., Sligar, S.G., Hydrostatic pressure reverses osmotic pressure effects on the specificity of EcoRI-DNA interactions (1994) Biochemistry, 33 (13), pp. 3787-3793Weber, G., Poian, A.T.D., Silva, J.L., Concentration dependence of the subunit association of oligomers and viruses and the modification of the latter by urea binding (1996) Biophys. J., 70, pp. 167-173Zlotnick, A., Distinguishing reversible from irreversible virus capsid assembly (2007) J. Mol. Biol., 366 (1), pp. 14-18Hogue, R., Asselin, A., Study of tobacco mosaic-virus in vitro disassembly by sucrose density gradient centrifugation and agarose-gel electrophoresis (1984) Can. J. Bot., 62, pp. 457-462Reshetnyak, Y.K., Burstein, E.A., Decomposition of protein tryptophan fluorescence spectra into log-normal components. II. The statistical proof of discreteness of tryptophan classes in proteins (2001) Biophys. J., 81, pp. 1710-1734Namba, K., Pattanayek, R., Stubbs, G., Visualization of protein-nucleic acid interactions in a virus. refined structure of intact tobacco mosaic virus at 2.9 a resolution by X-ray fiber diffraction (1989) J. Mol. Biol., 208, pp. 307-325Bhyravbhatla, B., Watowich, S.J., Caspar, D.L., Refined atomic model of the four-layer aggregate of the tobacco mosaic virus coat protein at 2.4-a resolution (1998) Biophys. J., 74, pp. 604-615Bonafe, C.F.S., Araujo, J.R.V., Silva, J.L., Intermediate states of assembly in the dissociation of gastropod hemocyanin by hydrostatic pressure (1994) Biochemistry, 33, pp. 2651-2660Erijman, L., Weber, G., Oligomeric protein associations: transition from stochastic to deterministic equilibrium (1991) Biochemistry, 30, pp. 1595-1599Ahmad, B., Khan, M.K.A., Haq, S.K., Khan, R.H., Intermediate formation at lower urea concentration in b isomer of human serum albumin: a case study using domain specific ligands (2004) Biochem. Biophys. Res. Commun., 314, pp. 166-173Dill, K.A., Shortle, D., Desnatured states of proteins (1991) Annu. Rev. Biochem., 60, pp. 795-82
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
