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BIOCHEMICAL FACTORS AFFECTING THE QUANTUM EFFICIENCY OF HYDROGEN PRODUCTION BY MEMBRANES OF GREEN PHOTOSYNTHETIC BACTERIA *
Author(s) -
Bernstein Jerome D.,
Olson John M.
Publication year - 1981
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1981.tb09070.x
Subject(s) - bacteria , photosynthesis , hydrogen production , membrane , production (economics) , chemistry , hydrogen , biology , biochemistry , organic chemistry , genetics , macroeconomics , economics
— Photohydrogen production, 200‐700 μmol H 2 h −1 (mg bacteriochlorophyll a) −1 has been obtained in a system containing unit membrane vesicles (Complex I) from the green photosynthetic bacterium Chiorobium limicola f. thiosulfatophilum , ascorbate, N,N,N′,N′‐tetramethyl‐ p ‐phenylene‐diamine, dithioerythritol, an oxygen scavenging mixture, either methyl viologen (MV) or clostridial ferredoxin (CPS Fd) as electron carrier, and either CPS hydrogenase or platinum asbestos as catalyst. All components are necessary for maximum activity, and spinach Fd cannot be substituted for CPS Fd. Higher rates of photohydrogen production are obtained using MV or CPS Fd with hydrogenase than with MV and Pt asbestos. The highest quantum efficiencies (7–10% at 0.2–0.9 mW absorbed light and over 20% at lower light) were obtained with CPS Fd, hydrogenase and non‐saturating 812 nm light. With saturating white light, however, rates of photohydrogen production varied relatively little among the various combinations of electron carrier and catalyst tested. The reaction rate is unaffected by 0.03% Triton X‐100, and is insensitive to treatment with antimycin a or m‐chloro‐carbonyl cyanide phenylhydrazone. This indicates that neither electron flow through an endogenous cyclic chain, nor maintenance of a proton gradient are involved in this process.