ANAEROBIC STOPPED-FLOW STUDIES OF INDOLE-3-ACETIC-ACID OXIDATION BY DIOXYGEN CATALYZED BY HORSERADISH-C AND ANIONIC TOBACCO PEROXIDASE AT NEUTRAL PH - CATALASE EFFECT

Citation
Ig. Gazarian et Lm. Lagrimini, ANAEROBIC STOPPED-FLOW STUDIES OF INDOLE-3-ACETIC-ACID OXIDATION BY DIOXYGEN CATALYZED BY HORSERADISH-C AND ANIONIC TOBACCO PEROXIDASE AT NEUTRAL PH - CATALASE EFFECT, Biophysical chemistry, 72(3), 1998, pp. 231-237
Citations number
16
Categorie Soggetti
Biophysics,Biology,"Chemistry Physical
Journal title
ISSN journal
03014622
Volume
72
Issue
3
Year of publication
1998
Pages
231 - 237
Database
ISI
SICI code
0301-4622(1998)72:3<231:ASSOIO>2.0.ZU;2-E
Abstract
The effect of order of reagent mixing in the absence and in the presen ce of catalase on the transient kinetics of indole-3-acetic acid (IAA) oxidation by dioxygen catalysed by horseradish peroxidase C and anion ic tobacco peroxidase at neutral pH has been studied. The data suggest that haem-containing plant peroxidases are able to catalyse the react ion in the absence of exogenous hydroperoxide. The initiation proceeds via the formation of the ternary complex enzyme --> IAA --> oxygen re sponsible for IAA primary radical generation. The horseradish peroxida se-catalysed reaction is independent of catalase indicating a signific ant contribution of free radical processes into the overall mechanism. This is in contrast to the tobacco peroxidase-catalysed reaction wher e the peroxidase cycle plays an important role. The transient kinetics of IAA oxidation catalysed by tobacco peroxidase exhibits a biphasic character with the first phase affected by catalase. The first phase i s therefore associated with the common peroxidase cycle while the seco nd is ascribed to native enzyme interaction with skatole peroxy radica ls yielding directly Compound II. (C) 1998 Elsevier Science B.V. All r ights reserved.