ABSTRACTA detailed kinetic study of the interaction between two ethylidene derivatives of tricyclic carbapenems, Lek 156 and Lek 157, and representative β-lactamases andd-alanyl–d-alanine peptidases (dd-peptidases) is presented. Both compounds are very efficient inactivators of theEnterobacter cloacae908R β-lactamase, which is usually resistant to inhibition. Preliminary experiments indicate that various extended-spectrum class C β-lactamases (ACT-1, CMY-1, and MIR-1) are also inactivated. With theE. cloacae908R enzyme, complete inactivation occurs with a second-order rate constant,k2/K′, of 2 × 104to 4 × 104M−1s−1, and reactivation is very slow, with a half-life of >1 h. Accordingly, Lek 157 significantly decreases the MIC of ampicillin forE. cloacaeP99, a constitutive class C β-lactamase overproducer. With the other serine β-lactamases tested, the covalent adducts exhibit a wide range of stabilities, with half-lives ranging from long (>4 h with the TEM-1 class A enzyme), to medium (10 to 20 min with the OXA-10 class D enzyme), to short (0.2 to 0.4 s with the NmcA class A β-lactamase). By contrast, both carbapenems behave as good substrates of theBacillus cereusmetallo-β-lactamase (class B). TheStreptomycessp. strain R61 and K15 extracellulardd-peptidases exhibit low levels of sensitivity to both compounds.
摘要本文对三环碳青霉烯类化合物的两种亚乙基衍生物 Lek 156 和 Lek 157 与代表性 β-内酰胺酶和 dd-丙氨酰-d-丙氨酸肽酶(dd-肽酶)之间的相互作用进行了详细的动力学研究。这两种化合物对通常具有抗药性的 Eterobacter cloacae908R β-内酰胺酶都是非常有效的灭活剂。初步实验表明,各种广谱 C 类 β-内酰胺酶(ACT-1、CMY-1 和 MIR-1)也被灭活。因此,Lek 157 能显著降低构成型 C β-内酰胺酶过量产生者 E. cloacaeP99 的氨苄西林 MIC。对于测试的其他丝氨酸 β-内酰胺酶,共价加合物的稳定性范围很广,半衰期从长(TEM-1 A 类酶为 4 小时)到中(OXA-10 D 类酶为 10 到 20 分钟)到短(NmcA A 类 β-内酰胺酶为 0.2 到 0.4 秒)不等。相比之下,两种碳青霉烯类都是蜡样芽孢杆菌金属β-内酰胺酶(B 类)的良好底物。链霉菌菌株 R61 和 K15 胞外肽酶对这两种化合物的敏感性较低。