MAD analyses of yeast 5-aminolaevulinate dehydratase: their use in structure determination and in defining the metal-binding sites.

摘要: MAD experiments attempting to solve the structure of 5-­aminolaevulinic acid dehydratase using Zn and Pb edges are described. The data obtained proved insufficient for a complete solution but were invaluable in subsequent identification metal-binding sites anomalous difference Fourier analyses once enzyme had been solved. These include highly inhibitory substitution an enzymic cofactor Zn2+ ion by Pb2+ ions, which represents major contribution towards understanding molecular basis lead poisoning. collected at edge also used with isomorphous replacement from same co-crystal Hg provide first delineation enzyme's quaternary structure. In this MADIR analysis, treated as native data. Anomalous Fouriers again used, revealing that Hg2+ substituted Pb2+, finding fundamental importance mercury addition, Pt2+ ions found bind place refined structures Pb- Hg-complexed enzymes presented 2.5 3.0 A resolution, respectively.