Sirohydrochlorin cobaltochelatase

The enzyme sirohydrochlorin cobaltochelatase (EC 4.99.1.3) catalyzes the reaction

cobalt-sirohydrochlorin + 2 H⁺ = sirohydrochlorin + Co²⁺

Sirohydrochlorin substrate of the enzme

sirohydrochlorin cobaltochelatase
Identifiers
EC no.	4.99.1.3
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

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⁺.

This enzyme belongs to the family of lyases, specifically the "catch-all" class of lyases that do not fit into any other sub-class. The systematic name of this enzyme class is cobalt-sirohydrochlorin cobalt-lyase (sirohydrochlorin-forming). Other names in common use include CbiK, CbiX, CbiXS, anaerobic cobalt chelatase, cobaltochelatase [ambiguous], and sirohydrochlorin cobalt-lyase (incorrect). 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]

See also

• Cobalamin biosynthesis

Structural studies

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