Table 1. Metabolic functions and enzymes that use cobamide cofactors.

SAM, S-adenosylmethionine.

Functional category	Cobamide-dependent enzymes or enzyme families
(a) Amino acid metabolism	Methionine synthase*†, glutamate mutase, lysine/ornithine aminomutases
(b) DNA and RNA synthesis	Ribonucleotide reductase†, epoxyqueuosine reductase†
(c) Carbon and nitrogen metabolism	Isomerases† (e.g., methylmalonyl-CoA mutase*, methyleneglutarate mutase), ethanolamine ammonia lyase, glycerol/diol dehydratases, methyltransferases (e.g., O-demethylases, methylamine methyltransferases, Wood-Ljungdahl corrinoid protein)
(d) Secondary metabolite synthesis	Radical SAM-B12 enzymes (biosynthesis of gentamicin, oxetanocin A, fosfomycin, phosalacine, thiostrepton, thienamycin)
(e) Others	Reductive dehalogenases, bacteriochlorophyll cyclase, light-sensing transcription factor, methytransferases [(MT), e.g., mercury MT, estrogen MT, methanogenesis marker protein 10]

^*Conserved in humans.

^†Among the four most common enzyme families in bacteria (5).