Diol dehydratase (DDH, EC:4.2.1.28) and its isofunctional homologue glycerol dehydratase (GDH, EC.4.2.1.30) are enzymes which catalyse the conversion of glycerol 1,2-propanediol, and 1,2-ethanediol to aldehydes [1]. These reactions require coenzyme B12. Cleavage of the Co-C bond of coenzyme B12 by substrates or coenzyme analogues results in inactivation during which coenzyme B12 remains tightly bound to the apoenzyme. This family comprises of the large subunit of the diol dehydratase and glycerol dehydratase reactivating factors whose function is to reactivate the holoenzyme by exchange of a damaged cofactor for intact coenzyme.

1: Biochemistry of coenzyme B12-dependent glycerol and diol dehydratases and organization of the encoding genes. Daniel R, Bobik TA, Gottschalk G; FEMS Microbiol Rev. 1998;22:553-566. PMID:9990728

2: Release of a damaged cofactor from a coenzyme B12-dependent enzyme: X-ray structures of diol dehydratase-reactivating factor. Shibata N, Mori K, Hieda N, Higuchi Y, Yamanishi M, Toraya T; Structure. 2005;13:1745-1754. PMID:16338403