The effects of alcohols on photosystem II reaction center complex preparations were examined. the order of effectiveness of alcohols to inhibit photosynthetic 02evolution was propargyl alcohol > glycerol > ethanol ≫ ethylene glycol. Inhibition by alcohols of H2O2-dependent 02evolution catalyzedby the oxygen-evolving complex (OEC) had the same concentration dependence as observed for the inhibition of photosynthetic 02evolution with the exception of glycerol, which inhibited H202-dependent 02evolution most effectively. Glycerol and propargyl alcohol were competitive inhibitors of H202-dependent 02evolution with inhibition constants of 12.9 mM and 1.16 M, respectively. Low concentrations of alcohols (<200 mM) in the presence of H202inhibited the OEC without causing the release of manganese. However, inactivation and loss of manganese can occur at higher concentrations of alcohol. the oxygen-evolving complex, in the presence of H202, catalyzes the oxidation of ethanol, glycerol, and propargyl alcohol to the respective aldehydes. A mechanism for this alcohol oxidase reaction catalyzed by the OEC is proposed.
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