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. 1969 Jul;63(3):956-62.
doi: 10.1073/pnas.63.3.956.

LIGHT-INDUCED OXIDATION OF A CHLOROPLAST B-TYPE CYTOCHROME AT -189 degrees C

D B Knaff  1 , D I Arnon
Affiliations

LIGHT-INDUCED OXIDATION OF A CHLOROPLAST B-TYPE CYTOCHROME AT -189 degrees C

D B Knaff et al. Proc Natl Acad Sci U S A. 1969 Jul.

Abstract

The b-type cytochromes of chloroplasts have heretofore been viewed as photosynthetic electron carriers that probably occupy an intermediate position in a light-induced electron flow. The oxidation-reduction of such intermediate electron carriers, being removed from the primary photochemical reaction linked to photon capture by chlorophyll, would be expected to show a temperature dependence. Evidence has now been obtained that cytochrome b(559) is photooxidized at -189 degrees C and that this photooxidation can be induced only by "short-wavelength" monochromatic light which activates the oxygen-evolving system in chloroplasts (photosystem II). In appears, therefore, that photooxidation of cytochrome b(559) is closely linked with photon capture by the chlorophyll pigments characteristic of photosystem II.

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