Inhibition of a cold-active alkaline phosphatase by imipenem revealed by in silico modeling of metallo-β-lactamase active sites.

We demonstrate the inhibition of the native phosphatase activity of a cold active alkaline phosphatase from Vibrio (VAP) (IC(50) of 44±4 (n=4)μM at pH 7.0 after a 30min preincubation) by a specific β-lactam compound (only by imipenem, and not by ertapenem, meropenem, ampicillin or penicillin G). The homologous scaffold was detected by an in silico analysis that established the spatial and electrostatic congruence of the active site of a Class B2 CphA metallo-β-lactamase from Aeromonas hydrophila to the active site of VAP. The tested β-lactam compounds did not inhibit Escherichia coli or shrimp alkaline phosphatase, which could be ascribed to the lower congruence indicated by CLASP. There was no discernible β-lactamase activity in the tested alkaline phosphatases. This is the first time a scaffold recognizing imipenem in an alkaline phosphatase (VAP) has been demonstrated.