Biochemistry of coenzyme B12-dependent glycerol and diol dehydratases and organization of the encoding genes.
Glycerol and diol dehydratases exhibit a subunit composition of alpha 2 beta 2 gamma 2 and contain coenzyme B12 in the base-on form. The dehydratase reaction proceeds via a radical mechanism. The dehydratases are subject to reaction inactivation by the substrate glycerol which is caused by a cessation of the catalytic cycle because coenzyme B12 is not regenerated, instead 5'-deoxyadenosine and a catalytically inactive cobalamin are formed. The genetic organization of the dehydratase genes is quite similar in all organisms. Downstream of the dehydratase genes an open reading frame encoding a polypeptide of approximately 600 amino acids was identified which is apparently involved in the reactivation of suicide-inactivated enzyme.
Daniel
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Institut für Mikrobiologie und Genetik der Georg-August-Universität, Göttingen, Germany. rdaniel@gwdg.de
Bobik
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Gottschalk
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D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000235:genetics; D001673:Biodegradation, Environmental; D003038:Cobamides / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006836:Hydro-Lyases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011408:Propanediol Dehydratase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019946:Propylene Glycol / Q000378:metabolism