Nuclear magnetic resonance of protamines. A 1H-NMR study of the interaction of clupeine fractions with mononucleotides.

The interaction of the three clupeine fractions, YI, YII, Z, and salmine fraction AI with mononucleotides has been examined by means of 1H nuclear magnetic resonance. The results obtained are interpreted in terms of electrostatic interactions between positive arginine guanidinyl groups and negative nucleotide phosphates. In addition, clupeine fraction YI and salmine fraction AI exhibit with guanine and adenine nucleotides a more specific interaction that leads to the formation of large aggregates in solution. The experimental data presented in this work demonstrate that the strength of interaction between clupeine YI and salmine AI with mononucleotides follows the order: 5'-dTMP approximately equal to 5'-dCMP much less than 5'-dAMP less than 5'-dGMP approximately equal to 5'-GMP.