Asparenomycins A, B and C, new carbapenem antibiotics. V. Inhibition of beta-lactamases.

Asparenomycins (ASMs) A, B and C inhibited a wide range of beta-lactamases including both cephalosporinases and penicillinases usually at concentrations less than 3 microM. On studying the mechanism of inhibition of beta-lactamases produced by Gram-negative bacteria by ASM A it was concluded that ASM A inhibited the beta-lactamases by acylating the enzymes. This conclusion was reached from the following observations. i) The inhibition was progressive with time. ii) The inhibitor formed stable complexes with the enzyme. iii) Before completing inhibition of one molecule of the enzyme, 1.8 molecules of the inhibitor were hydrolyzed.