EXAFS study of zinc coordination in bacitracin A

Bacitracin is a dodecapeptide antibiotic produced by Bacillus sp. The antib acterial activity depends upon the peptide binding a divalent metal. Hither to, the exact coordination of the cation has not been established. In parti cular the role played by the sulphur and nitrogen atoms of the thiazoline r ing of bacitracin A has not been clear. Here the coordination of Zn2+ by ba citracin A has been studied using extended X-ray absorption fine structure. The experimental data are consistent with a model in which zinc is coordin ated by one oxygen and three nitrogen atoms with the sulphur atom of the th iazoline ring not being directly involved in the zinc coordination. (C) 199 9 Elsevier Science B.V. All rights reserved.