Lewis M R, Deerfield D W, Hoke R A, Koehler K A, Pedersen L G, Hiskey R G
Department of Chemistry, University of North Carolina at Chapel Hill 27514.
J Biol Chem. 1988 Jan 25;263(3):1358-63.
The thermal decarboxylation of N-benzyloxycarbonyl-L-gamma-carboxyglutamic acid alpha-methyl ester [Z)-L-Gla-OMe) has been studied. In the presence of increasing amounts of calcium or magnesium ions, lyophilized powders of (Z)-L-Gla-OMe exhibit a corresponding increase in thermal stability. Both magnesium and calcium form relatively tight, thermally stable complexes with (Z)-L-Gla-OMe at high metal ion concentrations. Differences between Ca(II) and Mg(II) binding are noted at low metal ion concentrations, where (Z)-L-Gla-OMe is in excess. Under these conditions, complex formation with Mg(II) apparently favors a 2:1 Gla-magnesium ion complex in which both Gla residues are unstable to thermal decarboxylation. Calcium ion complexes, however, are found to favor a 3:1 Gla-calcium ion complex in which 1 of the 3 Gla residues is thermally stable.
对N-苄氧羰基-L-γ-羧基谷氨酸α-甲酯[（Z）-L-Gla-OMe]的热脱羧反应进行了研究。在存在越来越多的钙离子或镁离子的情况下，（Z）-L-Gla-OMe的冻干粉末表现出相应的热稳定性增加。在高金属离子浓度下，镁和钙都与（Z）-L-Gla-OMe形成相对紧密、热稳定的络合物。在低金属离子浓度下（此时（Z）-L-Gla-OMe过量），注意到Ca（II）和Mg（II）结合之间的差异。在这些条件下，与Mg（II）形成的络合物显然有利于形成2:1的Gla-镁离子络合物，其中两个Gla残基对热脱羧不稳定。然而，发现钙离子络合物有利于形成3:1的Gla-钙离子络合物，其中三个Gla残基中的一个对热稳定。
