Calcium biological coordination chemistry

Figure 17. Lead has been used as a heavy atom derivative to solve the phase problem in the crystal structures of a variety of protein including the calcium proteins calmodulin and synaptotagmin and die zinc protein 5-aminolevulinic acid dehydratase, ALAD. These structures provide useful insights into the coordination environments preferred by lead, which can bind both to carboxylate-rich calcium sites and thiol-rich zinc sites. Structures downloaded from die protein databank (3CLN, IRSY, 1AW5, IQNV) where necessary, lead was added to die figure based upon coordinates provided by the authors (240, 241, 243, 246). Figure adapted from Curr. Opin. Chem. Biol., Vol. 5, H.A. Godwin, The biological chemistry of lead, pp. 223-227, Copyright 2(X)1, with permission from Elsevier Science.

---