As a basis for elucidating the mechanism of interaction of the glycopeptide antibiotic bleomycin (BLM) with DNA a study is proposed to characterize BLM complexes with a series of nucleic acid derivatives: (1) mononucleotides (AMP, ADP, ATP, GMP and their corresponding deoxyribonucleotides), (2) self-complementary oligodeoxyribonucleotide duplexes (dG-dC and dA-dT types, with the appropriate degree of polymerization to be determined), and (3) double helical polydeoxyribonucleotides (poly dA-dT, poly dG-dC, poly dI-dC, and poly dA-dN, N equals 5 BrU and 5 IU). Preliminary experiments have demonstrated binding of BLM to representative members of each of the above classes of nucleic acid derivatives. The investigation will be conducted with the most abundant congener, BLM-A2. Comparative studies of a number of BLM derivatives--BLM-B2, phleomycin-D1, and tallysomycin-A and B--will be conducted to delineate the structure-function relationship of these antibiotics. The present study will focus on binding of BLM to nucleic acid derivatives. Degradation of nucleic acids under the experimental conditions to be employed in these studies is minimal. The role of BLM and possible metal cofactors in nucleic acid degradation is deferred to a subsequent investigation which will be based largely on the results obtained in this study. This investigation will be conducted in close collaboration with Dr. Dinshaw J. Patel (Bell Telephone Laboratories). Nuclear magnetic response (nmr) (1H, 13C and 31P) spectroscopy will be the principal method to be employed. Assignments of appropriate spectral resonances to specific nuclei of BLM-A, BLM-B2 and nucleic acid substrates are available. Fluorescence studies of BLM Binding to nucleic acids and ultraviolet spectroscopic measurements of the effects of BLM on the thermal denaturation of nucleic acid duplexes will also be conducted.
NIH ExPorter
NIH ExPorter