Construction of artificial nucleases is an attractive goal, having implications in molecular biology, genetic engineering and clinical medicine. The proposed research aims to answer important questions regarding the hydrolytic cleavage of DNA by investigating new molecules designed to hydrolytically cleave the DNA double-helix. In particular, a series of rhodium metallointercalators with covalently appended synthetic peptides which contain metal binding sites will be prepared. The proposed complexes are based upon recently prepared metal-peptide conjugates, Rh(phi)2L (phi = phenanthrenequinone diimine; L = bidentate ligands with a covalently appended peptide). The appended peptide will be systematically varied by introducing amino acid residues such as histidine, cysteine, or glutamate into the sequence, which will act as ligands, creating a coordination site where various divalent metal ions can bind, and potentially interact with and cleave the sugarphosphodiester backbone of DNA. Using the rhodium-peptide chimeras in the presence of divalent metal ions, the DNA cleavage reaction will be investigated, and the conditions for hydrolytic scission of the phosphate diester bond will be optimized. The new complexes will be fully characterized using multiple spectroscopic and physical methods. Analysis of the information gleaned from the characterization of the rhodium- peptide-metal species will allow the correlation of factors such as peptide secondary structure, metal ion type and affinity, coordinating ligands, and DNA affinity with hydrolysis. Through the study of the reactions of these complexes with DNA, important insights into DNA hydrolysis will be gained. As a result of these studies, significant progress toward the creation of artificial nucleases could be gained.
