Constrnction And Study Of Activity Of β-Lactamase Inhibitory Peptide

Objective: To synthesize and screenβ-lactamase inhibitory peptides which have certain inhibitory effect toβ-lactamase. To study the kinetics of biochemical characteristics and its inhibitory activity.For the treatment of clinical infection caused by bacterium which producingβ-lactamase.Methods:β-lactamase inhibitory peptide were three-dimensional designed and synthesized by solid phase synthesis method with computer. Eight clinicalβ-lactamase-producing isolates were selected in 2008 from our hospital. ESBLs strains were tested by Kirby—Bauer method. Theβ-lactamase were extracted and kinetic feature were studied. Their MIC to clinical commonly used antibiotics were tested. Tube-dilution-test was used for screening the activity ofβ-lactamase inhibitory peptide. The inhibitory activity of 3 inhibitors which commonly used in clinic and 3β-lactamase inhibitory peptide toβ-lactamase produced by the 8 bacteriums was studied with spectrophotomete. Inhibition constant(Ki) was obtained from dixon plot.And the relevance kinetic parameters of inhibition were calculated.Result: The eight strains were nearly all resistant to theβ-lactam antibiotics but highly susceptible to carbapenem. Different antibiotics were hydrolyzed by allβ-lactamase extracted from Escherichia coli and Klebsiella pneumoniae in different degree.A series of 6 short peptide were synthesized. 3 inhibitory peptide with the inhibitory activity were selected. We found that 3β-lactamase inhibitory peptide have a certain enzyme inhibitory activity through the study of substrate inhibition kinetics. The inhibition modality of 3β-lactamase inhibitory peptide and 3 inhibitors which commonly used in clinic are all competitive inhibition. But the inhibition constant of 3β-lactamase inhibitory peptide were all great. Sulbactam is the weakest of the relative inhibitory effect of three inhibitors, and the strongest is tazobactam.Conclusion: The treatment of infection by multidrug resistant ESBLs producing strains should use carbapenem preferred.There were differences between substrate profiles of differentβ-lactamases produced by differentβ-lactamases-producing strains. There were differences between inhibitory effects of three enzyme inhibitors on different strains producingβ-lactamase. The inhibitory activity of 3β-lactamase inhibitory peptide are weak.