|PROSITE documentation PDOC50970 [for PROSITE entry PS50970]|
The homocysteine (Hcy) binding domain is an ~300-residue module which is found in a set of enzymes involved in alkyl transfer to thiols:
The Hcy-binding domain utilizes a Zn(Cys)3 cluster to bind and activate Hcy. It has been shown to form a (β/α)8 barrel (see <PDB:1Q7Z>). The Hcy binding domain barrel is distorted to form the metal- and substrate-binding sites. To accommodate the substrate, strands 1 and 2 of the barrel are loosely joined by nonclassic hydrogen bonds; to accommodate the metal, strands 6 and 8 are drawn together and strand 7 is extruded from the end of the barrel. The cysteines ligating the catalytic zinc atom are located at the C-terminal ends of strands 6 and 8 [1,2].
The profile we developed covers the entire Hcy domain.Last update:
October 2005 / Text revised.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Evans J.C., Huddler D.P., Jiracek J., Castro C., Millian N.S., Garrow T.A., Ludwig M.L.|
|Title||Betaine-homocysteine methyltransferase: zinc in a distorted barrel.|
|2||Authors||Evans J.C., Huddler D.P., Hilgers M.T., Romanchuk G., Matthews R.G., Ludwig M.L.|
|Title||Structures of the N-terminal modules imply large domain motions during catalysis by methionine synthase.|
|Source||Proc. Natl. Acad. Sci. U.S.A. 101:3729-3736(2004).|