A Membrane Bound Cysteine Oxydase from the Cyanobacterium
نویسنده
چکیده
Membrane fractions o f the cyanobacterium Synechococcus 6301 obtained by french press treatment following sonication catalyzed an oxygen-dependent oxydation o f cysteine to cystine. For 1 0 2 consumed four cysteine were oxydized. Oxygen uptake was com pletely inhibited by 1 mM KCN. Only Dand L-cysteine were active and partial activity was observed with DL-homocysteine and cysteamine. N o activity was found with glutathione, mercaptoethanol, thioglycerol, dithioerythritol, or N-acetyl-L-cysteine. Cysteines with a blocked acid group such as O-methyl-L-cysteine and O-ethyl-L-cysteine were oxydized rapidly by Synechococcus membrane fractions. Rates o f about 200 (imol o f cysteine oxydized per mg chlorophyll and hour were measured. This cysteine respiration is discussed in relation to dark inactivation o f enzymes.
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