Determination of the concentration of active sites and the catalytic rate constant of recombinant formate dehydrogenase from Glycine max

2010 ◽  
Vol 65 (3) ◽  
pp. 127-130 ◽  
Author(s):  
E. G. Romanova ◽  
A. A. Alekseeva ◽  
E. V. Pometun ◽  
V. I. Tishkov
Keyword(s):  
Glycine Max ◽  
Rate Constant ◽  
Active Sites ◽  
Formate Dehydrogenase ◽  
Catalytic Rate Constant ◽  
Catalytic Rate

Solvent effects on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)-triazene II. Reactions in aprotic solvents

1990 ◽  
Vol 55 (1) ◽  
pp. 156-164 ◽  
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná ◽  
Miroslav Ludwig
Keyword(s):  
Rate Constant ◽  
Acid Catalyst ◽  
Kinetics And Mechanism ◽  
Aprotic Solvents ◽  
Catalytic Rate Constant ◽  
Negative Effect ◽  
Acid Catalyzed ◽  
Catalytic Rate ◽  
Positive Effect ◽  
Solvent Acidity

The effect of aprotic solvents (hexane, cyclohexane, dichloromethane, 1,2-dichloroethane, benzene, acetonitrile, acetone, 1,2-dimethoxyethane, ethyl acetate, dioxane) on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)triazene has been studied with trichloroacetic acid as the acid catalyst. It has been found that beside the non-dissociated monomer of the acid also its dimer acts as the catalytic species. With regard to the results obtained in protic solvents (the catalysis by proton and general acid) three cases can be encountered of the dependence of observed rate constant on analytical concentration of the acid. The effect of solvents (inclusive of the protic ones) on the catalytic rate constant of the reaction with the non-dissociated monomer of acid is best interpreted by the equation suggested by Koppel and Palm and by the solvent scale suggested by us earlier. The solvent acidity and polarity have positive effect, whereas its basicity has negative effect. The catalytic rate constant of the reaction with the acid dimer decreases with increasing solvent basicity and polarity, due predominantly to the decrease in the equilibrium constant of dimerization.

Solely electrochemical synthesis of Prussian Blue based nanozymes ‘artificial peroxidase’

2021 ◽  
Author(s):  
Maria A. Komkova ◽  
Kirill R. Vetoshev ◽  
Egor A Andreev ◽  
Arkady Karyakin
Keyword(s):  
Prussian Blue ◽  
Rate Constant ◽  
Electrochemical Synthesis ◽  
Catalytic Rate Constant ◽  
Flow Through ◽  
Catalytic Rate

We report on fully electrochemical flow-through synthesis of Prussian Blue based nanozymes defeating peroxidase in terms of more than 200 times higher catalytic rate constant (kcat=6∙104 s-1). Being reagentless, reproducible,...

Steric Effects in Acid-Catalyzed Decomposition and Base-Catalyzed Cyclization of 1-(2-Alkoxycarbonylphenyl)-3-phenyltriazenes

1996 ◽  
Vol 61 (5) ◽  
pp. 751-763 ◽  
Author(s):  
Oldřich Pytela ◽  
Aleš Halama
Keyword(s):  
Rate Constant ◽  
Nmr Spectra ◽  
Steric Effects ◽  
Catalytic Rate Constant ◽  
Rate Limiting Step ◽  
Acid Catalyzed ◽  
Catalytic Rate ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Derivatives Of

Eight derivatives of 1-(2-alkoxycarbonylphenyl)-3-phenyltriazene (R = methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, and allyl) have been synthesized and their UV-VIS, IR, 1H and 13C NMR spectra measured. The NMR spectra have been interpreted in detail. The kinetics of acid-catalyzed decomposition and base-catalyzed cyclization of the title compounds have been measured in 52.1% w/w methanol at 25.0 °C. The unit reaction order has been verified and the cyclization product has been identified. The pH-profiles obtained have been used to calculate the catalytic rate constants kA (acid-catalyzed decomposition) and kB (base-catalyzed cyclization) of all the derivatives; the constants have been interpreted with regard to inductive and steric effects. The catalytic rate constant kA has been found to be independent of the substituents. The catalytic rate constant kB depends statistically significantly upon both inductive and steric effects, the sensitivity to the former being more significant. The experimental results and their interpretation confirm the base-catalyzed cyclization mechanism with formation of tetrahedral intermediate as the rate-limiting step.

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