| Abstract
| - Hydrolases containing two metal ions connected by a bridging ligand catalyze reactionsimportant in carcinogensis, tissue repair, post-translational modification, control and regulation ofbiochemical pathways, and protein degradation. The aminopeptidase from Aeromonas proteolytica servesas a paradigm for the study of such bridged bimetallic proteases since its three-dimensional structure isknown to very high resolution and its catalytic reaction is amenable to spectroscopic examination. Herein,we report the X-ray crystal structure at 1.9 Å resolution of AAP complexed with 1-butaneboronic acid(BuBA). This structure suggests that this complex represents a snapshot of the proteolytic reaction in anarrested form between the Michaelis complex and the transition state. Comparison of the structure withspectroscopic and other data allows us to conclude that the apparently structurally symmetrical dizinc siteis actually asymmetric electrostatically.
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