Choline monooxygenase, an unusual iron-sulfur enzyme catalyzing the first step of glycine betaine synthesis in plants: Prosthetic group characterization and cDNA cloning

摘要

Plants synthesize the osmoprotectant glycine betaine via the route choline - betaine aldehyde - glycine betaine. In spinach, the first step is catalyzed by choline monooxygenase (CMO), a ferredoxin-dependent stromal en- zyme that has been hypothesized to be an oligomer of identical subunits and to be an Fe-S protein. Analysis by HPLC and matrix-assisted laser desorption ionization MS confirmed that native CMO contains only one type of subunit (Mr 42,864).