The kinetics of non-stoichiometric bursts of beta-lactam hydrolysis catalysed by class C beta-lactamases.
The kinetics of non-stoichiometric bursts of beta-lactam hydrolysis catalysed by class C beta-lactamases.
复制标题
C 类 β-内酰胺酶催化的 β-内酰胺水解非化学计量爆发的动力学。
DOI：
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发表时间：
1993
影响因子：
4.1
通讯作者：
Malcolm G. P. Page
中科院分区：
文献类型：
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作者：
Malcolm G. P. Page
观察到来自铜绿假单胞菌和几种肠杆菌科细菌的C类β-内酰胺酶在β-内酰胺类抗生素的水解率松弛到稳定的速率之前经历了快速的水解期。猝发的幅度对应于每摩尔酶对底物的1到10,000摩尔的水解度。爆发期水解率的衰减由两个指数反应组成，说明酶有三种不同的反应状态。对缓慢反应的β-内酰胺的酰化动力学的研究表明，处于缓慢平衡状态的游离酶有三种形式。因此，C类酶的爆裂动力学可以归因于与底物反应引起的酶在不同构象之间的重新分配。
Class C beta-lactamases from Pseudomonas aeruginosa and several species of the Enterobacteriaceae have been observed to undergo a rapid burst in hydrolysis of beta-lactam antibiotics before relaxation to a steady-state rate of hydrolysis. The amplitude of the burst corresponds to the hydrolysis of between 1 and 10,000 mol of the substrate per mol of enzyme. The decay of the rate of hydrolysis in the burst phase comprises two exponential reactions, which indicates that there are three different reactive states of the enzymes. Examination of the kinetics of acylation by slowly reacting beta-lactams suggests that there are three forms of the free enzyme in slow equilibrium. Thus it would appear that the burst kinetics exhibited by class C enzymes can be attributed to redistribution of the enzyme between different conformations induced by the reaction with substrate.