Crystal structure of human glyoxalase II and its complex with a glutathione thiolester substrate analogue.
BACKGROUND
Glyoxalase II, the second of two enzymes in the glyoxalase system, is a thiolesterase that catalyses the hydrolysis of S-D-lactoylglutathione to form glutathione and D-lactic acid.


RESULTS
The structure of human glyoxalase II was solved initially by single isomorphous replacement with anomalous scattering and refined at a resolution of 1.9 A. The enzyme consists of two domains. The first domain folds into a four-layered beta sandwich, similar to that seen in the metallo-beta-lactamases. The second domain is predominantly alpha-helical. The active site contains a binuclear zinc-binding site and a substrate-binding site extending over the domain interface. The model contains acetate and cacodylate in the active site. A second complex was derived from crystals soaked in a solution containing the slow substrate, S-(N-hydroxy-N-bromophenylcarbamoyl)glutathione. This complex was refined at a resolution of 1.45 A. It contains the added ligand in one molecule of the asymmetric unit and glutathione in the other.


CONCLUSIONS
The arrangement of ligands around the zinc ions includes a water molecule, presumably in the form of a hydroxide ion, coordinated to both metal ions. This hydroxide ion is situated 2.9 A from the carbonyl carbon of the substrate in such a position that it could act as the nucleophile during catalysis. The reaction mechanism may also have implications for the action of metallo-beta-lactamases.
Cameron
A D
AD
Department of Molecular Biology Uppsala University Biomedical Center Box 590, S-751 24, Uppsala, Sweden Structural Biology Laboratory Department of Chemistry University of York Heslington, York, UK YO10 5DD,. cameron@yorvic.york.ac.uk.
Ridderström
M
M
Olin
B
B
Mannervik
B
B
D000085:Acetates / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002101:Cacodylic Acid / Q000737:chemistry; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D000099301:Hydroxyacylglutathione Hydrolase
D000085:Acetates; D002101:Cacodylic Acid; D005978:Glutathione; D008670:Metals; D013869:Thiolester Hydrolases; D000099301:Hydroxyacylglutathione Hydrolase; C401205:S-(N-hydroxy-N-bromophenylcarbamoyl)glutathione