蜡样芽孢杆菌β-内酰胺酶I和II与半合成头孢霉素的相互作用。动力学研究。
Interaction of beta-lactamases I and II from Bacillus cereus with semisynthetic cephamycins. Kinetic studies.
作者信息
Martin Villacorta J, Arriaga P, Laynez J, Menendez M
机构信息
Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de León, Spain.
出版信息
Biochem J. 1991 Oct 1;279 ( Pt 1)(Pt 1):111-4.
The influence of C-6 alpha- or C-7 alpha-methoxylation of the beta-lactam ring in the catalytic action of class A and B beta-lactamases has been investigated. For this purpose the kinetic behaviour of beta-lactamases I (class A) and II (class B) from Bacillus cereus was analysed by using several cephamycins, moxalactam, temocillin and related antibiotics. These compounds behaved as poor substrates for beta-lactamase II, with high Km values and very low catalytic efficiencies. In the case of beta-lactamase I, the substitution of a methoxy group for a H atom at C-7 alpha or C-6 alpha decreased the affinity of the substrates for the enzyme. Furthermore, the acylation of cephamycins was completely blocked, whereas that of penicillins was slowed down by a factor of 10(4)-10(5), acylation being the rate-determining step of the process.
研究了β-内酰胺环的C-6α-或C-7α-甲氧基化对A类和B类β-内酰胺酶催化作用的影响。为此，通过使用几种头孢霉素、莫西沙星、替莫西林及相关抗生素，分析了蜡样芽孢杆菌β-内酰胺酶I（A类）和II（B类）的动力学行为。这些化合物对β-内酰胺酶II而言是较差的底物，具有高Km值和非常低的催化效率。就β-内酰胺酶I而言，在C-7α或C-6α处用甲氧基取代氢原子降低了底物对该酶的亲和力。此外，头孢霉素的酰化反应完全被阻断，而青霉素的酰化反应减慢了10^4 - 10^5倍，酰化反应是该过程的速率决定步骤。
Zotero 插件