S-adenosyl-L-homocysteine hydrolase
S-adenosyl-L-homocysteine hydrolase is an enzyme of the activated methyl cycle, responsible for the reversible hydration of S-adenosyl-L-homocysteine into adenosine and homocysteine.
AdoHcyase is a ubiquitous enzyme which binds and requires NAD+ as a cofactor. AdoHcyase is a highly conserved protein of about 430 to 470 amino acids. The family contains a glycine-rich region in the central part of AdoHcyase; a region thought to be involved in NAD-binding.
AdoHcyase is significantly associated with adenosine deaminase deficiency, which classically manifests in severe combine immunodeficiency. Accumulated adenosine derivatives, dATPs, irreversibly bind to and inhibit AdoHcyase, promoting the buildup of S-adenosyl-L-homocystine, a potent inhibitor of methyl transfer reactions.
This protein may use the morpheein model of allosteric regulation.
