THE FIRST SOLVATION SHELL OF MAGNESIUM-ION IN A MODEL PROTEIN ENVIRONMENT WITH FORMATE, WATER, AND X-NH3, H2S, IMIDAZOLE, FORMALDEHYDE, ANDCHLORIDE AS LIGANDS - AN AB-INITIO STUDY

The first coordination shell of an Mg(II) ion in a model protein envir onment is studied. Complexes containing a model carboxylate, an Mg(II) ion, various ligands (NH3, H2S, imidazole, and formaldehyde) and wate r of hydration about the divalent metal ion were geometry optimized. W e find that for complexes with the same coordination number, the unide ntate carboxylate-Mg(II) ion is greater than 10 kcal mol(-1) more stab le than the bidentate orientation. Imidazole was found to be the most stable ligand, followed in order by NH3, formaldehyde, H2O, and H2S. ( C) 1995 Wiley-Liss, Inc.