508 research outputs found
Effect of axial coordination on the kinetics of assembly and folding of the two halves of horse heart cytochrome C.
No full textThe kinetics of the assembly of two complementary fragments of oxidized horse heart cytochrome c (cyt c), namely the heme-containing fragment-(1-56) and the fragment-(57-104), have been characterized at different pH values. At neutral pH the fragment-(1-56) is hexacoordinated and has two histidines axially ligated to the heme-Fe(III) (Santucci, R., Fiorucci, L., Sinibaldi, F., Polizio, F., Desideri, A., and Ascoli, F. (2000) Arch. Biochem. Biophys. 379, 331-336), thus mimicking what occurs in the folding intermediate of cyt c. The kinetics of the formation of the complex between the two fragments are characterized at pH 7.0 by a slow rate constant that is independent of the concentration of the reactants; conversely, at a low pH the kinetics are much faster and depend on the concentration of the fragments. This behavior suggests that the rate-limiting step observed in the recombination process of the fragments at neutral pH (that leads to the final coordination of Met-80) has to be ascribed to the detachment of the "misligated" histidine. Thus, the faster recombination rate at a low pH can be related to the fact that histidine is protonated and not able to coordinate to the metal. Furthermore, the independence of the rate constant on the concentration of the reactants observed at pH 7.0 can be accounted for by the occurrence of a conformational transition, which takes place immediately after the two fragments collapse together, likely simulating what induces the detachment of the misligated histidine during cytochrome folding
Looking for the best experimental conditions to detail the protein solvation shell in a binary aqueous solvent via Small Angle Scattering
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Journal of Physics: Conference Series
Volume 177, 2009, Article number 012007
Open Access
Looking for the best experimental conditions to detail the protein solvation shell in a binary aqueous solvent via small angle scattering (Conference Paper)
Ortore, M.G.a ,
Sinibaldi, R.a,
Spinozzi, F.a,
Carbini, A.a,
Carsughi, F.ab,
Mariani, P.a
a Dipartimento di Scienze Applicate Ai Sistemi Complessi, Unit CNISM, Universit Politecnica Delle Marche, Ancona, Italy
b Institut für Festkörperforschung, Forschungszentrum, Jülich, Germany
Abstract
Protein hydration features attract particular interest in different fields, from biology up to physics, crossing chemistry and medicine. Particular attention is devoted to proteins dissolved in binary aqueous mixtures, since the presence of cosolvent can induce modifications in structural and functional properties. We have recently developed a methodology to obtain a quantitative description on protein solvation shell by a set of in-solution small angle scattering experiments, simultaneously analysed by a global-fit approach. In this paper, numerical simulations of small angle scattering curves are presented to figure out the sensitivity of the technique to different experimental conditions. Simulations concern two model proteins of different molecular weights and an unique cosolvent. A reliability test is introduced in order to find the best experimental conditions to be investigated, together with the most suitable scattering probe (neutrons or X-rays)
CEC enantioseparations on chiral monolithic columns: A study of the stereoselective degradation of (R/S)-dichlorprop [2-(2,4-dichlorophenoxy)propionic acid] in soil
No full textFor the study of the stereoselective degradation of the herbicide 2-aryloxipropionic acid dichlorprop (DCPP) in soil, a porous monolithic chiral column (100 μm id) was prepared by in situ copolymerization of glycidyl methacrylate, methyl methacrylate and ethylene glycol dimethacrylate in the presence of formamide and 1-propanol as the porogen solvents. Subsequently, the epoxide groups at the surface of the monolith were reacted with (+)-1-(4-aminobutyl)-(5R,8S,10R)-terguride as the chiral selector. Optimum conditions for the herbicide resolution by CEC were found using mobile phases consisting of acetic acid/ triethylamine mixtures in ACN-methanol (9:1 v/v). Under these conditions fully separation of DCPP enantiomers in the presence of clofibric acid (internal standard) was achieved in about 5 min. Experiments on the incubation of rac-DCPP in soil at room temperature showed the herbicide undergone during 23 incubation days to a degradation to levels ≤20% of the initial concentration, with rates for (R)-DCPP slower than (S)-DCPP. More interesting results were observed when herbicide enantiomers were individually incubated. In both the experiments, the formation of the opposite isomer in the presence of the initial one, and reversed enantiomeric interconversion in the case of (S)-DCPP was observed. (R)-DCPP was found to be the most persistent isomer after incubation. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
CAMP mediated cell growth regulation. I. Characterization of protein kinases in CHO cells
No full textEffect of axial coordination on the kinetics of assembly and folding of the two halves of horse heart cytochrome c
No full textThe kinetics of the assembly of two complementary fragments of oxidized horse heart cytochrome c (cyt c), namely the heme-containing fragment-(1-56) and the fragment-(57-104), have been characterized at different pH values. At neutral pH the fragment-(1-56) is hexacoordinated and has two histidines axially ligated to the heme-Fe(III) (Santucci, R., Fiorucci, L., Sinibaldi, F., Polizio, F., Desideri, A., and Ascoli, F. (2000) Arch. Biochem. Biophys. 379, 331-336), thus mimicking what occurs in the folding intermediate of cyt c. The kinetics of the formation of the complex between the two fragments are characterized at pH 7.0 by a slow rate constant that is independent of the concentration of the reactants; conversely, at a low pH the kinetics are much faster and depend on the concentration of the fragments. This behavior suggests that the rate-limiting step observed in the recombination process of the fragments at neutral pH (that leads to the final coordination of Met-80) has to be ascribed to the detachment of the "misligated" histidine. Thus, the faster recombination rate at a low pH can be related to the fact that histidine is protonated and not able to coordinate to the metal. Furthermore, the independence of the rate constant on the concentration of the reactants observed at pH 7.0 can be accounted for by the occurrence of a conformational transition, which takes place immediately after the two fragments collapse together, likely simulating what induces the detachment of the misligated histidine during cytochrome folding
Vascular network organization in posterior atrophic human mandible: a guide for an appropriate surgical approach
No full textBackground: The bone vascularity plays a key role for a successful surgical approach during implant placement on the posterior
atrophic lower jawbone. Although, some very old references are reported on animal studies, to the author best knowledge no
data are present in literature regarding this subject.
Aim/Hypothesis: The aim of this work was to evaluate the vascular arrangement in posterior, edentulous, atrophic mandibular
crests on humans
Protein folding, unfolding and misfolding: Role played by intermediate states
No full textMost proteins fold into their native structure through well defined pathways which involve a limited number of transient intermediates. Intermediates play a relevant role in the folding process; many diseases of genetic nature are in fact coupled with protein misfolding due to formation of stable, inactive intermediate species of the protein. This review deals with a number of diseases associated with protein misfolding and briefly describes the mechanism(s) responsible, at molecular level, for such pathologies. It is also considered the (native ⇆ molten globule) transition, recently observed for some proteins, in which a native protein converts into a stable compact intermediate state able to carry out distinct physiological functions inside the cell. A non-native compact form of cyt c, for example, appears to have a role in the programmed cell death (apoptosis) after that the protein is released from the mitochondrion and non-native forms of the same protein appear involved in some of the disorders attributed to amyloid formation. © 2008 Bentham Science Publishers Ltd
cAMP mediated cell growth regulation. II. Characterization of the biochemical change responsible for resistance to cAMP treatment
No full textProtein Kinases and Na/K ATPase. A tool to evaluate the sensitivity of cells to protein hormones
No full textGlycerol-induced formation of the molten globule from acid-denatured cytochrome c: Implication for hierarchical folding
No full textAt high concentration (98% or higher, v/v), glycerol induces collapse of acid-denatured cytochrome c into a compact state, the G(U) state, showing a molten globule character. The G(U) state possesses a nativelike a-helix structure but a tertiary conformation less packed with respect to the native state. The spectroscopic properties of the G(U) state closely resemble those of the molten globule stabilized by the organic solvent from the native protein (called the G(N) state), indicating that glycerol can stabilize the molten globule of cytochrome c either from the native or the acid-denatured protein. The G(U) and the G(N) states show spectroscopic (and, thus, structural) properties and stabilities comparable to those of molten globules stabilized by different effectors, despite the fact that the mechanisms involved in the molten globule formation may significantly differ. This implies in cytochrome c a hierarchy for the rupture (native-to-molten globule) or the formation (unfolded-to-molten globule) of intramolecular interactions leading to the stabilization of the molten globule state of the protein, independently from the effector responsible for the structural transition, in accord with the sequential model proposed by Englander and collaborators
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