Kinetics of β-Lactamases and Penicillin-Binding Proteins

摘要: The discovery of novel β-lactamases and penicillin-binding proteins (PBPs) often requires kinetic characterization. As such, the rate at which a β-lactamase hydrolyzes β-lactam is influenced by several factors. first concentration β-lactam, designated [S] expressed in units molarity. second temperature. temperature rises, molecular motion, hence collisions between rates interconversion intermediates increase. third factor presence inhibitors. inhibitors are clinically used to hinder activity β-lactamase. last pH: charge active-site groups conformation protein pH, enzyme crucially dependent on both these equations kinetics conceptual tools that allow us interpret quantitative measurements activity. Nitrocefin most practical reference compound, since accumulation ER* can be monitored 480 490 nm no interference expected with other β-lactams do not yield acyl enzymes absorbing this wavelength range. Several class D also exhibit substrate-induced inactivation (or biphasic kinetics) significant number substrates. Indeed, some but all cases, disappeared saturating bicarbonate was assumed completely maintain Lys carboxylated form.