β-Lactamase inhibitors

The β-lactamase inhibitor is a class of agents that can inhibit the activity of β-lactamase and hence avert or reduce the hydrolysis of inner β-lactam. Used in combination with β-lactam antibiotics, it can inhibit drug resistant bacteria, extended their antibacterial spectrum and enhance their antibacterial activity. According to their acting mechanism, β-lactamase inhibitors are divided into competitive inhibitor and noncompetitive inhibitor.

Competitive inhibitors
① Reversible competitive inhibitors such as cl- oxacillin and dicloxacillin, etc.:They compete with inner β-lactam for the active site within the β-lactamase without chemical interactions. Once removed, β-lactamase will regain its activity.

② Irreversible competitive inhibitors such as clavulanic acid and penicillanic sulfone: they will cause irreversible chemical reactions with β-lactamase and inactivate the enzyme. Even after the remained irreversible competitive inhibitors removed, the enzyme cannot be reproduced.

Noncompetitive inhibitors
they don’t compete with the substrate for the binding sites within the enzyme, but bind themselves onto the sites far from the catalytic sites and metamorphosize the enzyme and hence inactivate it. Methicillin, one of inhibitors above, is a competitive inhibitor at low concentrations, but a noncompetitive inhibitor at high concentrations.

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