title: Stereospecific binding of diastereomeric peptides to salmon sperm DNA.
abstract: Studies of the interaction specificities of L-lysyl-L-phenylalaninamide (1) and the diastereomeric dipeptide amide, L-lysyl-D-phenylalaninamide (2), with salmon sperm DNA reveal distinct differences in the binding site of the aromatic ring of the phenylalanine residue. The results of 1H nuclear magnetic resonance (NMR), spin-lattice relaxation rates, viscometric, and flow dichroism studies indicate the aromatic ring of 1 is "partially" inserted between base pairs of DNA whereas the aromatic ring of 2 points outward toward the solution. The terminal L-lysyl residue presumably interacts stereospecifically with DNA helix thus dictating the positioning of the aromatic ring of the C-terminal phenylalanine residue. In the accompanying paper (E. J. Gabbay et al. (1976), Biochemistry, following paper in this issue), the interaction of several oligopeptide amides (containing the N-terminal L-Lys-L-Phe residue) with DNA is examined. The results are found to be consistent with stereospecific binding of the terminal L-lysyl residue, and in addition, the evidence suggests that oligopeptides may bind to DNA via a modified single-stranded beta-sheet structure which is wrapped around the nucleic acid helix in a manner similar to that described by M. H. F. Wilkins (1956), Cold Spring Harbor Symp. Quant. Biol. 21, 75).
mesh_terms: D000577:Amides; D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D004247:DNA; D004151:Dipeptides; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D012474:Salmon; D013010:Sonication; D013094:Spermatozoa; D013237:Stereoisomerism
chemical_list: D000577:Amides; D004151:Dipeptides; D004247:DNA