Premium
Role of Carbonyl Cyanide m ‐Chlorophenylhydrazone in Enhancing Photobiological Hydrogen Production by Marine Green Alga Platymonas subcordiformis
Author(s) -
Ran Chunqiu,
Yu Xingju,
Jin Meifang,
Zhang Wei
Publication year - 2006
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp050289u
Subject(s) - hydrogenase , electron transport chain , photosystem i , chemistry , thylakoid , atp synthase , hydrogen production , photochemistry , proton transport , cyanide , photosystem ii , electrochemical gradient , uncoupling agents , biophysics , oxygen evolution , dcmu , photosystem , photosynthesis , oxidative phosphorylation , chloroplast , biochemistry , biology , enzyme , membrane , catalysis , inorganic chemistry , electrochemistry , gene , electrode
We demonstrated that a significant volume of H 2 gas could be photobiologically produced by a marine green alga Platymonas subcordiformis when an uncoupler of photophosphorylation, carbonyl cyanide m ‐chlorophenylhydrazone (CCCP), was added after 32 h of anaerobic dark incubation, whereas a negligible volume of H 2 gas was produced without CCCP. The role of CCCP in enhancing photobiological H 2 production was delineated. CCCP as an ADRY agent (agent accelerating the deactivation reactions of water‐splitting enzyme system Y) rapidly inhibited the photosystem II (PSII) activity of P. subcordiformis cells, resulting in a markedly decline in the coupled oxygen evolution. The mitochondrial oxidative respiration was only slightly inactivated by CCCP, which depleted O 2 in the light. As a result, anaerobiosis during the stage of photobiological H 2 evolution was established, preventing severe O 2 inactivation of the reversible hydrogenase in P. subcordiformis . The uncoupling effect of CCCP accelerates electron transfer from water due to a disruption of the proton motive force and release of ΔpH across the thylakoid membrane and thus enhances the accessibility of electron and H + to hydrogenase. The electrons for hydrogen photoevolution are mainly from the photolysis of water (90%). Upon the addition of CCCP, Chl a/b ratio increased, which implies a decrease in the light‐harvesting PSII antennae or an increase in PSII/PSI ratio, possibly resulting in higher efficiency of utilization of light energy. The enhancement of H 2 evolution by the addition of CCCP is mostly due to the combination of the above three mechanisms. However, the disruption of the proton gradient across the thylakoid membrane may prevent a sustained photobiological H 2 evolution due to a shortfall of ATP generation essential for the maintenance and repair functions of the cells.