1LT7

Oxidized Homo sapiens betaine-homocysteine S-methyltransferase in complex with four Sm(III) ions

Summary for 1LT7

• Entry DOI: 10.2210/pdb1lt7/pdb
• Related: 1lt8
• Descriptor: BETAINE-HOMOCYSTEINE METHYLTRANSFERASE, SAMARIUM (III) ION, CITRIC ACID, ... (4 entities in total)
• Functional Keywords: transferase, homocysteine metabolism, homocysteinemia, thiol alkyl transfer
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: Q93088
• Total number of polymer chains: 2
• Total formula weight: 90673.73

Authors

Evans, J.C.,Huddler, D.P.,Jiracek, J.,Castro, C.,Millian, N.S.,Garrow, T.A.,Ludwig, M.L. (deposition date: 2002-05-20, release date: 2002-09-11, Last modification date: 2024-11-13)

Primary citation

Evans, J.C.,Huddler, D.P.,Jiracek, J.,Castro, C.,Millian, N.S.,Garrow, T.A.,Ludwig, M.L.
Betaine-homocysteine methyltransferase: zinc in a distorted barrel.
Structure, 10:1159-1171, 2002

PubMed Abstract: Betaine-homocysteine methyl transferase (BHMT) catalyzes the synthesis of methionine from betaine and homocysteine (Hcy), utilizing a zinc ion to activate Hcy. BHMT is a key liver enzyme that is important for homocysteine homeostasis. X-ray structures of human BHMT in its oxidized (Zn-free) and reduced (Zn-replete) forms, the latter in complex with the bisubstrate analog, S(delta-carboxybutyl)-L-homocysteine, were determined at resolutions of 2.15 A and 2.05 A. BHMT is a (beta/alpha)(8) barrel that is distorted to construct the substrate and metal binding sites. The zinc binding sequences G-V/L-N-C and G-G-C-C are at the C termini of strands beta6 and beta8. Oxidation to the Cys217-Cys299 disulfide and expulsion of Zn are accompanied by local rearrangements. The structures identify Hcy binding fingerprints and provide a prototype for the homocysteine S-methyltransferase family.

PubMed: 12220488
DOI: 10.1016/S0969-2126(02)00796-7

Experimental method

X-RAY DIFFRACTION (2.15 Å)