Single-turnover and steady-state kinetics of hydrolysis of cephalosporins by β-lactamase I from Bacillus cereus

摘要: The kinetics of the hydrolysis two cephalosporins by beta-lactamase I from Bacillus cereus 569/H/9 has been studied single-turnover and steady-state methods. Single-turnover could be measured over time scale minutes when cephalosporin C was substrate. other substrate, 7-(2',4'-dinitrophenylamino)deacetoxycephalosporanic acid, hydrolysed even more slowly, potential for use in crystallographic studies beta-lactamases. Comparison showed that, both substrates, opening beta-lactam ring (i.e. acylation enzyme) rate-determining step. Thus non-covalent enzyme-substrate complex is expected to intermediate observed crystallographically.