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001-es BibID:	BIBFORM005971
Első szerző:	Damjanovich Sándor (biofizikus)
Cím:	Protein fluctuation and enzyme activity / Damjanovich, S., Somogyi, B., Welch, G. R.
Dátum:	1983
Megjegyzések:	The possible participation of protein fluctuation in enzyme activity is considered in this paper. Fluctuation is defined as vibrations, involving collective motion of a large number of atoms in protein molecules. Kinetic and thermodynamic aspects of protein fluctuation and enzyme-ligand interactions are discussed, paying special attention to the influence of electric fields and environmental microviscosity. A brief analysis of available experimental and theoretical data strongly suggests an interrelationship between protein fluctuation and enzyme function.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis Enzymes Kinetics Ligands metabolism Models,Chemical Motion Protein Conformation Thermodynamics
Megjelenés:	Journal of Theoretical Biology. - 105 : 1 (1983), p. 25-33. -
További szerzők:	Somogyi Béla (1945-2006) (biofizikus) Welch, Rickey G.
Internet cím:	elektronikus változat
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001-es BibID:	BIBFORM005993
Első szerző:	Somogyi Béla (biofizikus)
Cím:	The dynamic basis of energy transduction in enzymes / Béla Somogyi, G. Rickey Welch, Sándor Damjanovich
Dátum:	1984
ISSN:	0304-4173
Megjegyzések:	The most important idea underlying our treatment herein is the unity of the enzyme molecule and the medium. Appreciation of this relationship is vital, if enzymology is to graduate from its present reductionistic status to a more holistic posture. Enzymes are biological entities firstly, and isolated objects of physicochemical analysis secondly. Perhaps the most crucial 'biological lesson', particularly apropos of enzymes in intermediary metabolism, concerns the 'cytosociology' of enzyme action in vivo [94,128]. The natural habitat of many enzymes in the living cell is far different from that in bulk aqueous solution in vitro. In order to obtain a real grasp of the nature of enzyme function, one must ultimately couch enzymology in concepts emerging from contemporary cell biology [95]. Notwithstanding, analysis precedes synthesis; and one must needs begin with the individual enzyme molecule. The trenchant efforts of the physical chemist and the organic chemist have produced a wealth of information on the nature of the binding and catalytic events at the enzyme active site. While it is not yet possible to explain precisely the complete sequence of events in the catalytic process, nevertheless, the basic mechanisms by which enzymes effect catalysis (i.e., reduce activation energy) now seem apparent [81,129]. The new frontier is to be found, in exploring the dynamic role of the protein matrix [17]. Not only does the protein provide the 3-D scaffolding for active-site processes, but, more importantly, it serves as the local solvent for the bound chemical subsystem. Thus, the dynamical aspects of enzyme catalysis (for thermally based systems) must arise from the fluctuational properties of the protein molecule. This notion is the common denominator in all of the models in subsection IIC. It is the anisotropic nature of this fluctuational behavior, which would characterize the energy-transduction phenomenon leading to localized catalytic events at the active-site. In Section III we attempted to show that all of the various enzyme models contribute pieces to a single, all-embracing jig-saw puzzle. Some models focus on the dynamical properties of the protein per se, whereas others deal with the stochastic aspects of protein-solvent interaction. The two approaches are complementary, as are mutually interlocking pieces of a puzzle. The ultimate picture depicted by this 'jig-saw puzzle' is still somewhat vague--owing to the present paucity of empirical information on protein motions.(ABSTRACT TRUNCATED AT 400 WORDS)
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis Binding Sites Catalysis chemistry Cytoplasm Diffusion Electrochemistry Energy Metabolism Enzymes enzymology Hydrogen Bonding In Vitro Kinetics metabolism Models,Biological Protein Conformation Protons Solvents Thermodynamics Viscosity Water
Megjelenés:	Biochimica et Biophysica Acta (BBA). Reviews on Bioenergetics. - 768 : 2 (1984), p. 81-112. -
További szerzők:	Welch, Rickey G. Damjanovich Sándor (1936-2017) (biofizikus)
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001-es BibID:	BIBFORM005992
Első szerző:	Somogyi Béla (biofizikus)
Cím:	Forster-type energy transfer as a probe for changes in local fluctuations of the protein matrix / Bela Somogyi, Janos Matko, Sandor Papp, Jozsef Hevessy, G. Rickey Welch, Sandor Damjanovich
Dátum:	1984
Megjegyzések:	Much evidence, on both theoretical and experimental sides, indicates the importance of local fluctuations (in energy levels, conformational substates, etc.) of the macromolecular matrix in the biological activity of proteins. We describe here a novel application of the Forster-type energy-transfer process capable of monitoring changes both in local fluctuations and in conformational states of macromolecules. A new energy-transfer parameter, f, is defined as an average transfer efficiency, [E], normalized by the actual average quantum efficiency of the donor fluorescence, [phi D]. A simple oscillator model (for a one donor-one acceptor system) is presented to show the sensitivity of this parameter to changes in amplitudes of local fluctuations. The different modes of averaging (static, dynamic, and intermediate cases) occurring for a given value of the average transfer rate, [kt], and the experimental requirements as well as limitations of the method are also discussed. The experimental tests were performed on the ribonuclease T1-pyridoxamine 5'-phosphate conjugate (a one donor-one acceptor system) by studying the change of the f parameter with temperature, an environmental parameter expectedly perturbing local fluctuations of proteins. The parameter f increased with increasing temperature as expected on the basis of the oscillator model, suggesting that it really reflects changes of fluctuation amplitudes (significant changes in the orientation factor, k2, as well as in the spectral properties of the fluorophores can be excluded by anisotropy measurements and spectral investigations). Possibilities of the general applicability of the method are also discussed.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Energy Transfer Fluorescence Kinetics Mathematics metabolism Phosphorylase b Protein Conformation Proteins Ribonuclease T1 Spectrometry,Fluorescence Thermodynamics
Megjelenés:	Biochemistry. - 23 : 15 (1984), p. 3403-3411. -
További szerzők:	Matkó János (1952-) (biológus) Papp Sándor Hevessy József Welch, Rickey G. Damjanovich Sándor (1936-2017) (biofizikus)
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001-es BibID:	BIBFORM006022
Első szerző:	Welch, Rickey G.
Cím:	The role of protein fluctuations in enzyme action : a review / G. Rickey Welch, Béla Somogyi, Sándor Damjanovich
Dátum:	1982
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Binding Sites Catalysis Chemistry,Physical Energy Transfer Enzymes Mathematics metabolism Models,Biological Models,Chemical Protein Binding Protein Conformation Thermodynamics
Megjelenés:	Progress in biophysics and molecular biology. - 39 : 2 (1982), p. 109-146. -
További szerzők:	Somogyi Béla (1945-2006) (biofizikus) Damjanovich Sándor (1936-2017) (biofizikus)
Internet cím:	elektronikus változat
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