1984
DOI: 10.1111/j.1432-1033.1984.tb08230.x
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Kinetics of reduction by substrate or dithionite and heme-heme electron transfer in the multiheme hydroxylamine oxidoreductase

Abstract: Hydroxylamine oxidoreductase of Nitrosomonas catalyzes the dehydrogenation of NH2OH. It contains hemes c553, c559 and P460 in the ratio 5:2:1. At equilibrium four or five c hemes are reduced by NH2OH or NH2NH2, respectively. Heme P460 is the site of electron entry into the enzyme; electrons exit via P460 to O2 or H2O2 with rate constants of 30s−1. We report that hydroxylamine oxidoreductase has two categories of electron‐accepting sites: (a) heme P460, an H2O2‐sensitive site, which is reactive with NH2OH (2.2 … Show more

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Cited by 28 publications
(27 citation statements)
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“…The remaining 0.2 heme equivalent of c-553 were reduced more slowly in phase 2. This biphasic phenomenon had been observed previously at atmospheric pressure although the values of rate costants are slightly different from those published by us some years ago [7]. As in the case of the kinetics of formation of the carboxylated enzyme, this may be due to the different buffer used.…”
Section: Kinetics Of Formation Of the Co-complex With Ferrous P460contrasting
confidence: 63%
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“…The remaining 0.2 heme equivalent of c-553 were reduced more slowly in phase 2. This biphasic phenomenon had been observed previously at atmospheric pressure although the values of rate costants are slightly different from those published by us some years ago [7]. As in the case of the kinetics of formation of the carboxylated enzyme, this may be due to the different buffer used.…”
Section: Kinetics Of Formation Of the Co-complex With Ferrous P460contrasting
confidence: 63%
“…The kinetics of reduction of c hemes of the enzyme with NHzOH consisted of two phases. Rate constants (designated k, and k,) and changes in absorbance during the phases (designated dAl and dA2) were calculated as described previously [7]. The apparent activation volumes ( A V * ) were calculated from the pressure-dependence of k l ,co,…”
Section: Determination Of Kinetic Constants and Activation Volumementioning
confidence: 99%
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“…Also chemolithotrophic, nitrifying bacteria possess complex arrangements of internal membranes (54). Spheroplasts of Nitrosomonas do not contain internal vesicles (55). This suggests that internal membranes of those organisms are invaginations.…”
Section: Magnetosome-specific Gtpasementioning
confidence: 94%