Probing the stereochemistry of the active site of gamma-glutamyl transpeptidase using sulfur derivatives of l-glutamic acid
作者:Christian Lherbet、Jeffrey W. Keillor
DOI:10.1039/b310767a
日期:——
Gamma-glutamyl transpeptidase (GGT) catalyses the transfer of a γ-glutamyl moiety from a donor substrate to different acceptors, such as amino acids and water. GGT is known to display relatively low stereospecificity with respect to the α-stereocentre of its donor substrates. In this study we have studied its stereospecificity with respect to the stereocentre at the δ-position of different analogues of L-glutamic acid. Notably, L-methionine sulfoxide is well-recognised whereas L-methionine sulfone and L-methionine sulfoximine are not. Furthermore, when the synthetic γ-diastereoisomers of L-methionine sulfoxide were separated and tested, it was discovered that GGT shows remarkable stereospecificity at the γ-position, binding the SCSS diastereoisomer with a Ki of 3.5 mM, whereas the SCRS diastereoisomer is not recognised. Finally, using a sulfoxide as a new pharmacophore for GGT, we have synthesized and tested an analogue of glutathione to obtain a very promising competitive inhibitor with a Ki of (53 ± 3)
µM.
γ-谷氨酰转肽酶 (GGT) 催化 γ-谷氨酰部分从供体底物转移到不同的受体,例如氨基酸和水。已知 GGT 相对于其供体底物的 α-立体中心表现出相对较低的立体特异性。在本研究中,我们研究了其相对于 L-谷氨酸不同类似物的 δ 位立体中心的立体特异性。值得注意的是,L-甲硫氨酸亚砜已被广泛认可,而 L-甲硫氨酸砜和 L-甲硫氨酸亚砜亚胺则不然。此外,当分离和测试合成的L-蛋氨酸亚砜的γ-非对映异构体时,发现GGT在γ-位表现出显着的立体特异性,以3.5 mM的Ki结合SCSS非对映异构体,而SCRS非对映异构体则未被识别。最后,使用亚砜作为GGT的新药效团,我们合成并测试了谷胱甘肽的类似物,获得了一种非常有前途的竞争性抑制剂,其Ki为(53±3)
µM。