. Biological structure and function; proceedings. Biochemistry; Cytology. 354 DANIEL I. ARNON effective electron carrier in reactions involving cytochromes. For example, Massey [90] has found that cytochrome c is rapidly reduced in a non- enzymic reaction with reduced phenazine methosulphate. In Fig. 5, the intermediary electron carrier is vitamin K or FMN. The cyclic electron flow diagrams, illustrated by Figs. 4 and 5, are components of the scheme presented earlier [94]. The key reaction in the proposed mechanism, the photo-oxidation of chlorophyll by the loss of an electron, is based on a t
. Biological structure and function; proceedings. Biochemistry; Cytology. 354 DANIEL I. ARNON effective electron carrier in reactions involving cytochromes. For example, Massey [90] has found that cytochrome c is rapidly reduced in a non- enzymic reaction with reduced phenazine methosulphate. In Fig. 5, the intermediary electron carrier is vitamin K or FMN. The cyclic electron flow diagrams, illustrated by Figs. 4 and 5, are components of the scheme presented earlier [94]. The key reaction in the proposed mechanism, the photo-oxidation of chlorophyll by the loss of an electron, is based on a type of reaction in photochemistry that was experi- mentally documented by Lew'is and Lipkin [96]. They found, by illuminating a variety of substances in rigid media, "that one of the commonest photochemical processes is the mere loss of an electron by an activated molecule" [96]. The evidence for the then (in 1942) "new and â ^ Cof actor. '~P ADP Chi '. V ^ Cyt LIGHT ~PâADPâKatp, Anaerobic cyclic photophosphorylation Fig. 5. Scheme for anaerobic cyclic photophosphorylation catalyzed by vitamin K, or FMN. Details in the text. somewhat surprising phenomenon" [96] was, for example, "that chemical oxidation at room temperature and photo-oxidation at liquid air tempera- ture (of tri-/)-tolylamine) have given the same substance, namely, the positive ion left, (/>-CH3C6H4)3N+, when one electron has been removed" [96]. In the reactions studied by Lewis and Lipkin the fate of the ejected electron was uncertain but, as they pointed out, "the electron must lie in a potential hole which is deep enough so that the large electrostatic field of the ion is unable to dislodge it" for considerable periods of time. This was indicated by the fact that "the (blue) color ( of the 'odd ion' formed) persists at liquid air temperature for several days, but at only slightly higher temperatures the color disappears. Then presumably the electron. Please n
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