Cameron A D, Ridderström M, Olin B, Mannervik B
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,.
Structure. 1999 Sep 15;7(9):1067-78. doi: 10.1016/s0969-2126(99)80174-9.
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.
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.
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.
乙二醛酶II是乙二醛酶系统中两种酶的第二种，是一种硫酯酶，催化S-D-乳酰谷胱甘肽水解形成谷胱甘肽和D-乳酸。
人类乙二醛酶II的结构最初通过单对映体置换和反常散射解析，并在1.9 Å分辨率下进行精修。该酶由两个结构域组成。第一个结构域折叠成一个四层β折叠夹心结构，类似于金属β-内酰胺酶中的结构。第二个结构域主要是α螺旋结构。活性位点包含一个双核锌结合位点和一个延伸到结构域界面的底物结合位点。模型在活性位点包含乙酸盐和二甲胂酸盐。第二个复合物来自浸泡在含有缓慢底物S-(N-羟基-N-溴苯基氨基甲酰基)谷胱甘肽溶液中的晶体。该复合物在1.45 Å分辨率下进行精修。它在不对称单元的一个分子中包含添加的配体，在另一个分子中包含谷胱甘肽。
锌离子周围配体的排列包括一个水分子，可能以氢氧根离子的形式，与两个金属离子配位。这个氢氧根离子位于距离底物羰基碳2.9 Å的位置，在催化过程中它可以作为亲核试剂。该反应机制也可能对金属β-内酰胺酶的作用有影响。
