DETERMINATION OF THE RATE CONSTANTS OF THE INTERSYSTEM CROSSING PROCESSES TO THE INDIVIDUAL MULTIPLETS OF THE LOWEST TRIPLET STATE

1968 ◽  
Author(s):  
M. A. El-Sayed ◽  
L. Hall
Keyword(s):  
Triplet State ◽  
Rate Constants ◽  
Intersystem Crossing ◽  
The Individual

scholarly journals Isomerization of an enzyme-coenzyme complex in yeast alcohol dehydrogenase-catalysed reactions

2003 ◽  
Vol 68 (2) ◽  
pp. 77-84 ◽  
Author(s):  
Vladimir Leskovac ◽  
Svetlana Trivic ◽  
Draginja Pericin
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Kinetic Mechanism ◽  
Yeast Alcohol Dehydrogenase ◽  
Catalyzed Reactions ◽  
The Individual ◽  
Individual Rate ◽  
Catalyzed Oxidation

In this work, all the rate constants in the kinetic mechanism of the yeast alcohol dehydrogenase-catalyzed oxidation of ethanol by NAD+, at pH 7.0, 25 ?C, have been estimated. The determination of the individual rate constants was achieved by fitting the reaction progress curves to the experimental data, using the procedures of the FITSIM and KINSIM software package of Carl Frieden. This work is the first report in the literature showing the internal equilibrium constants for the isomerization of the enzyme-NAD+ complex in yeast alcohol dehydrogenase-catalyzed reactions.

Triplet-State Electron Spin Resonance of Chlorophyll a and b Molecules and Complexes in PMMA and MTHF. I: Experimental Determination of Fine-Structure and Rate Constants

1978 ◽  
Vol 33 (1) ◽  
pp. 83-93 ◽  
Author(s):  
W. Hagele ◽  
D. Schmid ◽  
H. C. Wolf
Keyword(s):  
Triplet State ◽  
Chlorophyll A ◽  
Rate Constants ◽  
Resonance Field ◽  
Zero Field ◽  
Chlorophyll B ◽  
Low Concentrations ◽  
Spin Resonance ◽  
Chlorophyll A And B

The triplet state zero-field splittings and the rate constants for the population and depopulation of the triplet spin sublevels have been investigated for chlorophyll a and chlorophyll b in polymethylmethacrylate (PMMA) and methyltetrahydrofurane (MTHF) as a function of the concentration. In PMMA both chlorophyll a and chlorophyll b yielded only one ESR spectrum in the entire range of concentration which could be covered (1.5 × 10-5 - 1 × 10-3 mole/1). In MTHF the results were more complicated. At low concentrations (up to 103 mole/1) only one spectrum was observed, at higher concentrations additional spectra were detectable (all together two for chlorophyll a and five for chlorophyll b at 10-1 mole/1). The assignment of these spectra was facilitated by observing the "triplet resonance-field identity" which connects the resonancefield strengths for the canonical orientations of one particular species. Furthermore, the rate constants for some of these species could be determined.

Determination of absolute rate constants for an excited triplet state

1978 ◽  
Vol 68 (1) ◽  
pp. 327 ◽  
Author(s):  
Willem R. Leenstra ◽  
Martin Gouterman ◽  
Alvin L. Kwiram
Keyword(s):  
Triplet State ◽  
Rate Constants ◽  
Excited Triplet State ◽  
Absolute Rate ◽  
Excited Triplet

scholarly journals The linkage between binding of the C-terminal domain of hirudin and amidase activity in human α-thrombin

1993 ◽  
Vol 289 (2) ◽  
pp. 475-480 ◽  
Author(s):  
R de Cristofaro ◽  
B Rocca ◽  
B Bizzi ◽  
R Landolfi
Keyword(s):  
Rate Constants ◽  
Binding Constant ◽  
Amidase Activity ◽  
Equilibrium Binding ◽  
Viscosity Effects ◽  
The Individual ◽  
Individual Rate ◽  
Hydrolysis Of ◽  
Equilibrium Binding Constant

A method derived from the analysis of viscosity effects on the hydrolysis of the amide substrates D-phenylalanylpipecolyl-arginine-p-nitroaniline, tosylglycylprolylarginine-p-nitroanaline and cyclohexylglycylalanylarginine-p-nitroalanine by human alpha-thrombin was developed to dissect the Michaelis-Menten parameters Km and kcat into the individual rate constants of the binding, acylation and deacylation reactions. This method was used to analyse the effect of the C-terminal hirudin (residues 54-65) [hir-(54-65)] domain on the binding and hydrolysis of the three substrates. The results showed that the C-terminal hir-(54-65) fragment affects only the acylation rate, which is increased approx. 1.2-fold for all the substrates. Analysis of the dependence of acylation rate constants on hirudin-fragment concentration, allowed the determination of the equilibrium binding constant of C-terminal hir-(54-65) (Kd approximately 0.7 microM). In addition this peptide was found to competitively inhibit thrombin-fibrinogen interaction with a Ki which is in excellent agreement with the equilibrium constant derived from viscosity experiments. These results demonstrate that binding of hir-(54-65) to the fibrinogen recognition site of thrombin does not affect the equilibrium binding of amide substrates, but induces only a small increase in the acylation rate of the hydrolysis reaction.

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