4,716 research outputs found
Protein Complexity via Non-Native States: Binding, Stability, and Structural Studies of Calbindin D9k and HAMLET (Human alpha-lactalbumin Made LEthal to Tumor cells).
No full textUsing optical spectroscopy, nuclear magnetic resonance (NMR), and differential scanning Calorimetry (DSC), I have studied two different calcium binding proteins that can form kinetically trapped altered states. Calcium is very important in numerous biological processes such as blood coagulation, signal transduction, muscle contraction and bone formation. Calcium binding to proteins regulates these processes. First, the influence of a bound water molecule on the cooperativity of calcium binding in an EF hand protein, calbindin D9k, was studied. Affinity, kinetics, stability and structure properties of two mutant proteins showed the importance of water molecules in the binding process. Surprisingly, one mutant formed a 3D domain swapped dimer upon crystallization. We showed that packing of a hydrophobic substitution in the linker region is the driving force for formation of the kinetically trapped dimer. The human genome consists of fewer genes than predicted but maintain complexity by mechanisms on different levels from DNA to proteins. In my second project, I studied a system that changes function and structure upon binding a fatty acid ligand. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex of human alpha-lactalbumin and oleic acid (C18:1, 9 cis) that kills tumor cells by an apoptosis-like mechanism. Previously, it has been shown that only calcium-free, apo, alpha-lactalbumin can be converted to HAMLET. Apo alpha-lactalbumin is partly unfolded. A bovine version, BAMLET and D87A-BAMLET, a converted non-calcium binding, and thus permanently partly unfolded, were both able to kill tumor cells. HAMLET maintained a high affinity for Ca2+ but D87A-BAMLET was active with no Ca2+ bound. The conclusion is that partial unfolding of alpha-lactalbumin is necessary but not sufficient to trigger cell death, and that the activity of HAMLET is defined both by the protein and the lipid cofactor. Furthermore, a functional Ca2+-binding site is not required for conversion of alpha-lactalbumin to the active complex or to cause cell death. The stability towards thermal and urea denaturation was measured for HAMLET, BAMLET and human and bovine alpha-lactalbumin. Three lines of evidence indicate that HAMLET and BAMLET are kinetic traps. I) HAMLET/BAMLET has lower stability than alpha-lactalbumin, although it is a complex of alpha-lactalbumin and oleic acid. II) Its denaturation is irreversible and HAMLET/BAMLET is lost after denaturation. III) Formation of HAMLET/BAMLET requires a specific conversion protocol. NMR studies show that oleic acid is bound in a u-shaped fashion in HAMLET, but the spectra of the protein are poorly dispersed further underlining previous observations of a highly dynamic and unstructured state under physiological conditions
Protein Complexity via Non-Native States: Binding, Stability, and Structural Studies of Calbindin D9k and HAMLET (Human alpha-lactalbumin Made LEthal to Tumor cells)
No full textPopular Abstract in Swedish Kalcium är inblandat i många viktiga processer i kroppen. Kalciumbindande proteiner är viktiga i detta sammanhang. Det finns ofta en vattenmolekyl med på bindningsstället i proteinet och vi har studerat hur den påverkar bindningsegenskaperna. Kalcium är inblandat i många viktiga processer i kroppen. Kalciumbindande proteiner är viktiga i detta sammanhang. Jag har studerat ett protein som agerar som kalciumbuffert i celler, calbindin D9k. Det finns en vattenmolekyl med i kalciumbindningsstället i proteinet och vi har studerat hur den påverkar bindningsegenskaperna. HAMLET är ett komplex mellan mjölkproteinet alfalaktalbumin och oljesyra. Det dödar cancerceller med är harmlöst för vanliga celler. Vi har tittat på hur kalciumbindningen ändrats och hur den på verkar bildandet av komplexet och dess anticanceraktivitet. Vidare har vi studerat hur proteinet står emot uppvärmning och en kemikalie som förstör proteiner. Då komplexet är mindre stabilt mot dessa påfrestningar än alfalaktalbumin själv och förlorar sin aktivitet samt blir fri oljesyra och protein så tolkar vi det som att komplexet är en s.k. kinetisk fälla. Ytterligare bevis på detta är att man måste tillverka det enligt en speciell procedur då det inte fungerar att bara blanda oljesyra och protein. Oljesyran har formen av ett U i proteinet och komplexet är mycket rörligare och mer ostrukturerat än det fria proteinet vid normala fysiologiska förhållanden.Using optical spectroscopy, nuclear magnetic resonance (NMR), and differential scanning Calorimetry (DSC), I have studied two different calcium binding proteins that can form kinetically trapped altered states. Calcium is very important in numerous biological processes such as blood coagulation, signal transduction, muscle contraction and bone formation. Calcium binding to proteins regulates these processes. First, the influence of a bound water molecule on the cooperativity of calcium binding in an EF hand protein, calbindin D9k, was studied. Affinity, kinetics, stability and structure properties of two mutant proteins showed the importance of water molecules in the binding process. Surprisingly, one mutant formed a 3D domain swapped dimer upon crystallization. We showed that packing of a hydrophobic substitution in the linker region is the driving force for formation of the kinetically trapped dimer. The human genome consists of fewer genes than predicted but maintain complexity by mechanisms on different levels from DNA to proteins. In my second project, I studied a system that changes function and structure upon binding a fatty acid ligand. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex of human alpha-lactalbumin and oleic acid (C18:1, 9 cis) that kills tumor cells by an apoptosis-like mechanism. Previously, it has been shown that only calcium-free, apo, alpha-lactalbumin can be converted to HAMLET. Apo alpha-lactalbumin is partly unfolded. A bovine version, BAMLET and D87A-BAMLET, a converted non-calcium binding, and thus permanently partly unfolded, were both able to kill tumor cells. HAMLET maintained a high affinity for Ca2+ but D87A-BAMLET was active with no Ca2+ bound. The conclusion is that partial unfolding of alpha-lactalbumin is necessary but not sufficient to trigger cell death, and that the activity of HAMLET is defined both by the protein and the lipid cofactor. Furthermore, a functional Ca2+-binding site is not required for conversion of alpha-lactalbumin to the active complex or to cause cell death. The stability towards thermal and urea denaturation was measured for HAMLET, BAMLET and human and bovine alpha-lactalbumin. Three lines of evidence indicate that HAMLET and BAMLET are kinetic traps. I) HAMLET/BAMLET has lower stability than alpha-lactalbumin, although it is a complex of alpha-lactalbumin and oleic acid. II) Its denaturation is irreversible and HAMLET/BAMLET is lost after denaturation. III) Formation of HAMLET/BAMLET requires a specific conversion protocol. NMR studies show that oleic acid is bound in a u-shaped fashion in HAMLET, but the spectra of the protein are poorly dispersed further underlining previous observations of a highly dynamic and unstructured state under physiological conditions
Accentuation of Jonas Rėza's Psalter of 1625
No full textStraipsnyje trumpai apžvelgiama dabartinių kalbų kirčio ženklų istorija – nuo Antikos kalbininko Aristofano Bizantiečio žymėtų akūto, gravio ir cirkumflekso iki Mažvydo Katekizme pažymėto į riestinį cirkumfleksą panašaus ženklo, Baltramiejaus Vilento raštų, D. Kleino gramatikos, J. Rėzos psalmyno ,,Psalteras Dowido“ kirčio ženklų. Išsamiau straipsnyje analizuojamas 1625 m. J. Rėzos psalmyno kirčiavimas, iš graikų perimti kirčio ženklai, paties autoriaus įsivestas kirčio ženklas. Straipsnyje taip pat aptariama Rėzos psalmyne vartotų kirčio ženklų funkcijos, kirčio ženklų vartojimo įvairavimas, sąsajos tarp psalmyno kirčiavimo ir D. Kleino gramatikos Reikšminiai žodžiai: Akūtas; Gravis; Cirkumfleksas; Psalmynas; Lietuvių kalbos istorija; KirčiavimasThis article gives a brief overview of the history of the accent marks of languages from Antiquity linguist Aristophanes of Byzantium marked the acute accent, grave accent and circumflex accent until the sign similar to a tilde-shaped circumflex marked in Mažvydas’ Catechism, and accent signs of Baltramiejus Vilentas’ writings, Daniel Klein‘s grammer, and Jonas Rhesa’s Psalter of David. The article gives a comprehensive analysis of the accentuation made by Jonas Rhesa in the psalter, accent marks taken from Greek, and an accent mark developed by the author himself. The article also discusses the functions of the accent marks used in Rhesa’s psalter, the variation of the usage of accent marks and the interaction between the accentuation of the psalter and D. Klein’s grammer
Jonas, Hobbes e le forme della paura
No full textThis essay aims at clarifying the concept of Jonas’s heuristic of fear. Although it has been severely criticized, fear remains an aspect of his thought which has drawn little attention, particularly regarding the role it plays in the elaboration of the imperative of responsibility. Jonas elaborates a new concept of fear, moulded by the particular form of uncertainty brought about by the technological age. Although critics have interpreted Jonas’ attempt as an ethics founded on irrationality and emotion, the present analysis shows that Jonas affirms a cognitivist theory of fear. The concept of fear he discusses in The Imperative of Responsibility is not an emotion as an immediate physical and psychological reaction, but a form of evaluative thinking that is part of responsibility. In order to illustrate form and function of fear in Jonas thought, I will refer to the meanings of fear in Hobbes, an author Jonas himself refers to
Jonas, Hobbes e le forme della paura
No full textThis essay aims at clarifying the concept of Jonas’s heuristic of fear. Although it has been severely criticized, fear remains an aspect of his thought which has drawn little attention, particularly regarding the role it plays in the elaboration of the imperative of responsibility. Jonas elaborates a new concept of fear, moulded by the particular form of uncertainty brought about by the technological age. Although critics have interpreted Jonas’ attempt as an ethics founded on irrationality and emotion, the present analysis shows that Jonas affirms a cognitivist theory of fear. The concept of fear he discusses in The Imperative of Responsibility is not an emotion as an immediate physical and psychological reaction, but a form of evaluative thinking that is part of responsibility. In order to illustrate form and function of fear in Jonas thought, I will refer to the meanings of fear in Hobbes, an author Jonas himself refers to
Electrophysiological Heterogeneity of Fast-Spiking Interneurons: Chandelier versus Basket Cells
No full textIn the prefrontal cortex, parvalbumin-positive inhibitory neurons play a prominent role in the neural circuitry that subserves working memory, and alterations in these neurons contribute to the pathophysiology of schizophrenia. Two morphologically distinct classes of parvalbumin neurons that target the perisomatic region of pyramidal neurons, chandelier cells (ChCs) and basket cells (BCs), are generally thought to have the same "fast-spiking" phenotype, which is characterized by a short action potential and high frequency firing without adaptation. However, findings from studies in different species suggest that certain electrophysiological membrane properties might differ between these two cell classes. In this study, we assessed the physiological heterogeneity of fast-spiking interneurons as a function of two factors: species (macaque monkey vs. rat) and morphology (chandelier vs. basket). We showed previously that electrophysiological membrane properties of BCs differ between these two species. Here, for the first time, we report differences in ChCs membrane properties between monkey and rat. We also found that a number of membrane properties differentiate ChCs from BCs. Some of these differences were species-independent (e.g., fast and medium afterhyperpolarization, firing frequency, and depolarizing sag), whereas the differences in the first spike latency between ChCs and BCs were species-specific. Our findings indicate that different combinations of electrophysiological membrane properties distinguish ChCs from BCs in rodents and primates. Such electrophysiological differences between ChCs and BCs likely contribute to their distinctive roles in cortical circuitry in each species. © 2013 Povysheva et al
A Comparison of Thermoresistive and Thermoelectric Sensing Structures for Calorimetric Anemometers
No full textAuthor Jonas Astl, BScMasterarbeit Johannes Kepler Universität Linz 2024Arbeit gesperr
A Comparison of Thermoresistive and Thermoelectric Sensing Structures for Calorimetric Anemometers
No full textAuthor Jonas Astl, BScMasterarbeit Johannes Kepler Universität Linz 2024Arbeit gesperr
Dotnuvos stoty: eilėraščiai
No full textPoetry in Lithuanian written by Sacred Heart University faculty author Jonas Zdanys
Laiko inkliuzai: eilėraščiai: lietuvių ir anglų kalbomis = Inclusions in Time: Selected Poems
No full textPoetry in Lithuanian by Antanas A. Jonynas. Translated by Sacred Heart University faculty author Jonas Zdanys and others. Edited by Jonas Zdanys. Lithuanian and English on opposite pages
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