Leyh-Bouille M, Nguyen-Distèche M, Pirlot S, Veithen A, Bourguignon C, Ghuysen J M
Biochem J. 1986 Apr 1;235(1):177-82. doi: 10.1042/bj2350177.
The values of the kinetic parameters that govern the interactions between the Streptomyces K15 DD-peptidase and beta-lactam compounds were determined by measuring the inactivating effect that these compounds exert on the transpeptidase activity of the enzyme and, in the case of [14C]benzylpenicillin and [14C]cefoxitin, by measuring the amounts of acyl-enzyme formed during the reaction. K15 DD-peptidase binds benzylpenicillin or cefoxitin at a molar ratio of 1:1. Benzylpenicilloate is the major product released during breakdown of the acyl-enzyme formed with benzylpenicillin. Benzylpenicillin is not a better acylating agent than the amide Ac2-L-Lys-D-Ala-D-Ala and ester Ac2-L-Lys-D-Ala-D-lactatecarbonyl-donor substrates. beta-Lactam compounds possessing a methoxy group on the alpha-face of the molecule show high inactivating potency.
通过测量这些化合物对该酶转肽酶活性的失活作用，以及在[14C]苄青霉素和[14C]头孢西丁的情况下，通过测量反应过程中形成的酰基酶的量，确定了控制链霉菌K15 DD-肽酶与β-内酰胺化合物之间相互作用的动力学参数值。K15 DD-肽酶以1:1的摩尔比结合苄青霉素或头孢西丁。苄青霉素酸酯是在与苄青霉素形成的酰基酶分解过程中释放的主要产物。苄青霉素不是比酰胺Ac2-L-Lys-D-Ala-D-Ala和酯Ac2-L-Lys-D-Ala-D-乳酸羰基供体底物更好的酰化剂。在分子α面具有甲氧基的β-内酰胺化合物显示出高失活效力。
