scholarly journals Stereochemical aspects of the oxidation of 4-ethylphenol by the bacterial enzyme 4-ethylphenol methylenehydroxylase

1990 ◽  
Vol 269 (3) ◽  
pp. 815-819 ◽  
Author(s):  
C D Reeve ◽  
M A Carver ◽  
D J Hopper
Keyword(s):  
Cytochrome C ◽  
Dehydrogenase Activity ◽  
Electron Acceptor ◽  
Complete Conversion ◽  
Bacterial Strains ◽  
Horse Heart Cytochrome ◽  
No Formation ◽  
Bacterial Enzyme ◽  
Ethanol Dehydrogenase ◽  
Horse Heart Cytochrome C

The O2-independent hydroxylase 4-ethylphenol methylenehydroxylase (4EPMH) from Pseudomonas putida JD1 catalysed the complete conversion of 4-ethylphenol into 1-(4-hydroxyphenyl)ethanol together with a small amount of 4-hydroxyacetophenone, but with no formation of the side product 4-vinylphenol reported to be formed when the similar enzyme p-cresol methylhydroxylase (PCMH) catalyses this reaction. The enantiomer of 1-(4-hydroxyphenyl)ethanol produced by 4EPMH was R(+) when horse heart cytochrome c or azurin was used as electron acceptor for the enzyme. PCMHs from various bacterial strains produced the S(-)-alcohol. Both enantiomers of 1-(4-hydroxyphenyl)ethanol were substrates for conversion into 4-hydroxyacetophenone by 4EPMH, but the S(-)-isomer was preferred. The Km and kcat. were 1.2 mM and 41 s-1 respectively for the S(-)-alcohol and 4.7 mM and 22 s-1 for the R(+)-alcohol. In addition to the 1-(4-hydroxyphenyl)ethanol dehydrogenase activity of 4-EPMH, NAD(+)-linked dehydrogenase activity for both enantiomers of the alcohol was found in extracts of Ps. putida JD1.

Kinetics and mechanism of the reaction between oxidized cytochrome c and ascorbic acid

1991 ◽  
Vol 56 (2) ◽  
pp. 478-490 ◽  
Author(s):  
Joaquin F. Perez-Benito ◽  
Conchita Arias
Keyword(s):  
Ascorbic Acid ◽  
Cytochrome C ◽  
Redox Reactions ◽  
Arrhenius Equation ◽  
Horse Heart Cytochrome ◽  
First Order ◽  
Acidic Form ◽  
Ph Range ◽  
Horse Heart Cytochrome C ◽  
Mechanism Of The Reaction

The reaction between horse-heart cytochrome c and ascorbic acid has been investigated in the pH range 5.5 – 7.1 and at 10.0 – 25.0 °C. The rate shows a first-order dependence on the concentration of cytochrome c, it increases in a non-linear way as the concentration of ascorbic acid increases, it increases markedly with increasing pH and, provided that the ionic strength of the medium is high enough, it fulfills the Arrhenius equation. The apparent activation energy increases as the pH of the solution increases. The results have been explained by means of a mechanism that includes the existence of an equilibrium between two forms (acidic and basic) of oxidized cytochrome c: cyt-H+ -Fe3+ + OH- cyt -Fe3+ + H2O, whose equilibrium constant is (6.7 ± 1.4). 108 at 25.0 °C, the acidic form being more reducible than the basic one. It is suggested that there is a linkage of hydrogenascorbate ion to both forms of cytochrome c previous to the redox reactions. Two possibilities for the oxidant-reductant linkage (binding and adsorption) are discussed in detail.

ChemInform Abstract: Total Synthesis of Horse Heart Cytochrome c

ChemInform ◽  
2010 ◽  
Vol 23 (27) ◽  
pp. no-no
Author(s):  
C. DI BELLO ◽  
C. VITA ◽  
L. GOZZINI
Keyword(s):  
Cytochrome C ◽  
Total Synthesis ◽  
Horse Heart Cytochrome ◽  
Horse Heart Cytochrome C
Sign in / Sign up

Export Citation Format

Share Document