The reduction of chromate and synthesis of chromium(III) complexes with nucleotides and amino acids at physiological conditions

The Cr(III) ion is thought to be responsible for forming DNA-Cr(III)-protein crosslinks in the living system, but Cr(III) has difficulty passing through the membrane of the cell. However, since the chromate ion penetrates the membrane much more easily, it is reasonable to study the reduction of chromate and the formation of Cr(III)-amino acid complexes within the living system. Since the reduction of chromate by small molecular weight reductants in vitro has been done and a number of the Cr(III)-amino acid complexes have been synthesized, we chose the most reasonable reductants to reduce the chromate in the presence of ligands (AMP, amino acids etc.) under physiological conditions and prepared a number of the Cr(III)-amino acid complexes. The spectra of the complexes, the ratio of the Cr(III) to amino acid in each complex and the extinction coefficients of the complexes were determined. Also, the relative abilities of the amino acids to coordinate Cr(III) were compared and the chelating groups which may be responsible for the crosslinks, and the possible structure of the complexes are suggested.