Coordination Chemistry Reviews 190–192 (1999) 331–355 Structural properties of the nickel ions in urease: novel insights into the catalytic and inhibition mechanisms Stefano Ciurli a, *, Stefano Benini b , Wojciech R. Rypniewski b , Keith S. Wilson c , Silvia Miletti a , Stefano Mangani d a Institute of Agricultural Chemistry, Uniersity of Bologna, Viale Berti Pichat 10, I -40127 Bologna, Italy b European Molecular Biology Laboratory, c /o DESY, Notkestraße 85, D-22603 Hamburg, Germany c Department of Chemistry, Uniersity of York, Heslington, York YO15DD, UK d Department of Chemistry, Uniersity of Siena, Pian dei Mantellini 44, I -53100 Siena, Italy Accepted 13 March 1999 Contents Abstract .................................................... 331 1. Biological background ......................................... 332 2. Spectroscopic investigations of the urease active site structure .................. 333 3. Crystallographic studies of the native enzyme ............................ 334 4. Crystallographic studies of urease mutants .............................. 341 5. Crystallographic studies of urease – inhibitor complexes ...................... 345 6. Crystallographic study of a transition state analogue bound to urease .............. 348 7. A novel proposal for the urease mechanism ............................. 350 References .................................................. 353 Abstract This work provides a comprehensive critical summary of urease spectroscopy, crystallogra- phy, inhibitor binding, and site-directed mutagenesis, with special emphasis given to the www.elsevier.com/locate/ccr Abbreiations: JBU, jack bean urease; KAU, Klebsiella aerogenes urease; BPU, Bacillus pasteurii urease; -ME, -mercaptoethanol; PPD, phenylphosphorodiamidate; AHA, acetohydroxamic acid; XAS, X-ray absorption spectroscopy; EXAFS, extended X-ray absorption fine structure; CD, circular dichroism; MCD, magnetic circular dichroism. * Corresponding author. Tel.: +39-051-259794; fax: +39-051-243362. E-mail address: sciurli@agrsci.unibo.it (S. Ciurli) 0010-8545/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved. PII:S0010-8545(99)00093-4