Molecular models of acidic peptides from pea bud chromatin and seminal plasma. Divalent cations-mediated interaction with DNA.

Small acidic peptides have been isolated from biological fluids (blood and seminal plasma) and from chromatin of several tissues. Their biological activity is related to the control of cell growth and gene expression. This work is an approach to the study of peptide structure-function relationship. Purified fractions from seminal plasma and pea bud chromatin were subjected to fast ion bombardment mass spectrometry. The results obtained were analyzed according to biochemical characteristics of the peptides studied and some possible molecular models have been designed. Two of the proposed sequences were synthesized and their biological activity assayed in cells and cell-free systems. The results demonstrate that the synthetic peptides are able to bind to DNA in the presence of divalent cations (Mg2+, Fe2+, Cu2+) with consequent inhibition of DNA transcription.