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.
Synthesis of S-alkyl l-homocysteine analogues of glutathione and their kinetic studies with γ-glutamyl transpeptidase
作者:Christian Lherbet、Christian Gravel、Jeffrey W. Keillor
DOI:10.1016/j.bmcl.2004.04.072
日期:2004.7
A series of S-alkyl L-homocysteine analogues of glutathione was synthesized with varied oxidation state of the sulfur and tested for inhibition of rat kidney gamma-glutamyl transpeptidase (GGT). The strong selectivity of the enzyme with respect to the sulfur oxidation state reveals important information for the development of powerful competitive inhibitors. (C) 2004 Elsevier Ltd. All rights reserved.