Sirohydrochlorin cobaltochelatase

The enzyme sirohydrochlorin cobaltochelatase (EC 4.99.1.3) catalyzes the reaction In the forward direction of reactions towards cobalamin in anaerobic bacteria, the two substrates of this enzyme are sirohydrochlorin and Co2+; its two products are cobalt-sirohydrochlorin and H+.

The systematic name of this enzyme class is cobalt-sirohydrochlorin cobalt-lyase (sirohydrochlorin-forming).

This enzyme is part of the biosynthetic pathway to cobalamin (vitamin B12) in bacteria such as Salmonella typhimurium and Bacillus megaterium.

It has also been identified as the enzyme which inserts nickel into sirohydrochlorin in the biosynthesis of cofactor F430, reaction EC 4.99.1.11.

[1] As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1TJN and 2DJ5.