Münch R, Wombacher H, Körber F
J Clin Chem Clin Biochem. 1981 Sep;19(9):953-60. doi: 10.1515/cclm.1981.19.9.953.
The use of a spectrophotometric method is reported for the characterization of a beta-lactamase (EC 3.5.2.6) from Bacillus cereus. Absorption coefficients of the mercaptides of various penicillins were determined with this method. The enzyme was kinetically characterized using penicillins. Inhibition studies with Bacillus cereus beta-lactamase and various penicillins showed a substrate type of inhibition, indicating an additional binding site for substrates without catalytic activity. The dissociation constant of this binding site was determined and the influence of this binding site upon the catalytic activity is discussed. Studies with beta-lactamase-stable penicillins as inhibitors and various penicillins showed different types of inhibition, which indicated the presence of an additional catalytically inactive binding site. Experiments with clavulanic acid, a beta-lactamase inhibitor without remarkable intrinsic antibacterial activity, showed a mixed type of inhibition. Based on the hypothesis for the existence of more than one substrate binding site on the enzyme, clavulanic acid was found to be bonded to both the catalytic active and the catalytic inactive binding site.
报道了一种分光光度法用于表征蜡样芽孢杆菌的β-内酰胺酶（EC 3.5.2.6）。用该方法测定了各种青霉素硫醇盐的吸收系数。使用青霉素对该酶进行了动力学表征。蜡样芽孢杆菌β-内酰胺酶与各种青霉素的抑制研究显示出底物类型的抑制作用，表明存在一个无催化活性的底物额外结合位点。测定了该结合位点的解离常数，并讨论了该结合位点对催化活性的影响。以β-内酰胺酶稳定的青霉素作为抑制剂与各种青霉素的研究显示出不同类型的抑制作用，这表明存在一个额外的无催化活性的结合位点。用克拉维酸（一种无显著内在抗菌活性的β-内酰胺酶抑制剂）进行的实验显示出混合型抑制作用。基于酶上存在多个底物结合位点的假设，发现克拉维酸与催化活性结合位点和催化无活性结合位点均有结合。
