Acetyl-CoA pathway of autotrophic growth. Identification of the methyl-binding site of the CO dehydrogenase.

摘要: CO dehydrogenase, a key enzyme of the acetyl-CoA pathway autotrophic growth, has been methylated using 14CH3I or 14CH3-corrinoid plus ferredoxin. Acetyl-CoA was synthesized from resulting 14CH3-CO CO, and CoASH, with about 50% yield available 14C without addition other enzymes except dehydrogenase disulfide reductase. Even reductase could be replaced by dithioerythritol. Amino acid analysis showed two radioactive peaks, one which migrated as S-methylcysteine but very close to methyl ester glutamic acid. By oxidation H2O2, component this peak identified sulfone. after synthesis demonstrated that there large decrease in radioactivity containing S-methyl-cysteine. The compound present second not identified; no its radioactivity. nonreducing gel electrophoresis followed autoradiography, it shown beta subunit is acceptor. These results demonstrate cysteine acceptor per se catalyzes acetyl-CoA.