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Updated: Aug 17, 2026

Synthesis of 1,2-Azaborines and the Preparation of Their Protein Complexes with T4 Lysozyme Mutants
Published on: March 25, 2017
Reactions of pyrazolylborate-zinc-hydroxide complexes related to beta-lactamase activity
Florian Gross1, Heinrich Vahrenkamp
1Institut für Anorganische und Analytische Chemie der Universität Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany.
Abstract:
Simple beta-lactams and their hydrolysis products, the beta-amino acids, react with TpZn-OH under deprotonation. The latter become semibidentate carboxylate ligands with a NH...O hydrogen bond, and the former become N-bound beta-lactamide ligands. Likewise the antibiotic derivatives 6-aminopenicillanic acid and 7-aminocephalosporanic acid are incorporated as carboxylate ligands. beta-Lactams bearing nitrophenyl or acyl substituents at the nitrogen atoms are opened hydrolytically by TpZn-OH, and the resulting N-substituted beta-amino acids are attached to zinc by their carboxylate functions. Only with trifluoroacetyl as the N-substituent does the hydrolytic cleavage occur at the external amide bond, yielding the free beta-lactam and TpZn-trifluoroacetate. The kinetic investigation of the opening reactions has shown them to be of second order like all other TpZn-OH-induced hydrolytic cleavages, thereby supporting the four-center mechanism for the monozinc beta-lactamases.
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