EXAFS and Near Edge Structure IV

J. Phys. Colloques 47 (1986) C8-1169-C8-1172
DOI: 10.1051/jphyscol:19868228

METAL COORDINATION IN ZINC ENZYMES

M.C. FEITERS^{1, 2}, C. LITTLE^{3, 4} et S.G. WALEY<sup>3

1</sup>  Department of Chemistry, University of Manchester, GB-Manchester M13 9PL, Great-Britain
²  Synchrotron Radiation Source, SERC Daresbury Laboratory, GB-Warrington WA4 4AD, Great-Britain
³  Sir William Dunn School of Pathology, University of Oxford, South Parks Road, GB-Oxford Ox1 3RE, Great-Britain
⁴  On leave from Institute of Medical Biology, University of Tromsø, N-9000 Tromsø, Norway

Résumé
Nous avons étudié des exo-enzymes de Bacillus Cereus, phospholipase-C et ß-lactamase II, par zinc et cobalt K-edge EXAFS. Nous rapportons que les zincs dans les centre structural et catalytique de phospholipase-C ont cinq ligants, tandis que le cobalt, substitué dans le centre catalytique, a six ligants. Le zinc dans le centre actif de ß-lactamase II a un ligant soufre, à bas nombre de coordination ou haut facteur Debye-Waller, outre des ligants imidazoles.

Abstract
We have studied the Bacillus Cereus exo-enzymes, phospholipase-C and ß-lactamase II, by Zn and Co K-edge EXAFS. We report that the zincs in the structural and catalytic sites of the former enzyme are 5-coordinate, whereas cobalt, substituted in the catalytic site, is 6 coordinate. The ß-lactamase II active site zinc has sulphur coordination, with either low occupancy or high Debye-Waller factor, in addition to imidazole coordination.