Hg-coordination studies of oligopeptides containing cysteine, histidine and tyrosine by Hg-199m-TDPAC

In order to study the interaction of histidine- and tyrosine-containing pep tide chains with Hg(II), the nuclear quadrupole interaction (NQI) of Hg-199 m in the Hg complexes of the oligopeptides Alanyl-Alanyl-Histidyl-Alanyl-Al anine-amid (AAHAA-NH2) and Alanyl-Alanyl-Tyrosyl-Alanyl-Alanine-amid (AAYAA -NH2) was determined by time differential perturbed angular correlation and is compared with previous data on Alanyl-Alanyl-Cysteyl-Alanyl-Alanyl (AAC AA-OH). The Hg-199m-NQIs depend on the oligopeptide to Hg(II) stoichiometry and indicate that two-fold and four-fold coordinations occur for the bound Hg(II).