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Cytochrome photooxidations inChromatiumchromatophores: Each P870 oxidizes two cytochrome C422 hemes

Authors
Journal
Biochimica et Biophysica Acta (BBA) - Bioenergetics
0005-2728
Publisher
Elsevier
Publication Date
Volume
189
Issue
3
Identifiers
DOI: 10.1016/0005-2728(69)90170-4

Abstract

Abstract A single, 20-nsec actinic flash oxidizes all of the P870 in Chromatium chromatophores, but only about one half of the cytochrome C422. A second flash, 1–10 msec later, oxidizes most of the remaining cytochrome. The cytochromes which undergo oxidation on the first and second flashes are indistinguishable with respect to their absorption spectra, their kinetics of oxidation and reduction, and their response to N-methylphenazonium methosulfate (PMS) or continuous actinic illumination. The effect of PMS is to increase the total amount of cytochrome C422 which is in the reduced form in the dark, and which is available for photooxidation. The conclusion is that each P870 reaction center is responsible for the oxidation of two C422 hemes.

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