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dc.contributor.authorKobayashi, Ken
dc.contributor.authorHayashi, Ken
dc.contributor.authorSwallow, A Johnen
dc.date.accessioned2010-08-17T11:20:23Z
dc.date.available2010-08-17T11:20:23Z
dc.date.issued1990-02-27
dc.identifier.citationReactions of the NAD radical with higher oxidation states of horseradish peroxidase. 1990, 29 (8):2080-4 Biochemistryen
dc.identifier.issn0006-2960
dc.identifier.pmid2328239
dc.identifier.urihttp://hdl.handle.net/10541/109740
dc.description.abstractThe reactions of the NAD radical (NAD.) with ferric horseradish peroxidase and with compounds I and II were investigated by pulse radiolysis. NAD. reacted with the ferric enzyme and with compound I to form the ferrous enzyme and compound II with second-order rate constants of 8 X 10(8) and 1.5 X 10(8) M-1 s-1, respectively, at pH 7.0. In contrast, no reaction of NAD. with native compound II at pH 10.0 nor with diacetyldeutero-compound II at pH 5.0-8.0 could be detected. Other reducing species generated by pulse radiolysis, such as hydrated electron (eaq-), superoxide anion (O2-), and benzoate anion radical, could not reduce compound II of the enzyme to the ferric state, although the methylviologen radical reduced it. The results are discussed in relation to the mechanism of catalysis of the one-electron oxidation of substrates by peroxidase.
dc.language.isoenen
dc.subject.meshFerric Compounds
dc.subject.meshHorseradish Peroxidase
dc.subject.meshKinetics
dc.subject.meshNAD
dc.subject.meshOxidation-Reduction
dc.subject.meshPeroxidases
dc.titleReactions of the NAD radical with higher oxidation states of horseradish peroxidase.en
dc.typeArticleen
dc.contributor.departmentInstitute of Scientific and Industrial Research, Osaka University, Japan.en
dc.identifier.journalBiochemistryen
html.description.abstractThe reactions of the NAD radical (NAD.) with ferric horseradish peroxidase and with compounds I and II were investigated by pulse radiolysis. NAD. reacted with the ferric enzyme and with compound I to form the ferrous enzyme and compound II with second-order rate constants of 8 X 10(8) and 1.5 X 10(8) M-1 s-1, respectively, at pH 7.0. In contrast, no reaction of NAD. with native compound II at pH 10.0 nor with diacetyldeutero-compound II at pH 5.0-8.0 could be detected. Other reducing species generated by pulse radiolysis, such as hydrated electron (eaq-), superoxide anion (O2-), and benzoate anion radical, could not reduce compound II of the enzyme to the ferric state, although the methylviologen radical reduced it. The results are discussed in relation to the mechanism of catalysis of the one-electron oxidation of substrates by peroxidase.


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