Active site urease

IV. MODELS OF THE INHIBITED UREASE ACTIVE SITE V. FUTURE PERSPECTIVES... 

Parallel to the phenolato-based systems, related alkoxo-bridged ligands were developed for emulating the urease active site, in particular by the groups of Krebs, Nakao, and Yamaguchi. In contrast to the related 3 compound, complexes 11 feature only a single carboxylate bridge, but an additional solvent molecule is attached to each metal ion (63, 64). 

M Polarization of the carbonyl bond by coordination activates it for nucleophilic attack. This situation is assumed to occur by the bridging hydroxide, which appears to be most suitably arranged when the picolinamide-0 is located in a bridging position, although its transient shift to a terminal site cannot be ruled out. The failure of 32 to hydrolyze picolinamide confirms that generation of a nucleophilic hydroxide is required for the reaction to proceed (82). In subsequent work, 33 was then found to serve as a valuable functional model for the urease active site (see Section III.B.4). 

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