Isolation of the homogeneous constituents from non-diffusible sugar-peptide (NSP) fraction originating from bovine plasma. III. The method of isolation and partial characterization of the four peptide constituents.

The purification of four different peptides from the NSP fraction of bovine plasma, using: organic solvents extraction, column Sephadex G-50 filtration, thin-layer Sephadex G-25 electrophoresis in 5 M guanidine hydrochloride and thin-layer Bio-Gel P-6 electrophoresis methods was described. The molecular weights of the isolated peptides and their amino acid composition were determined. The dose-dependent effect two of the four peptides on 3H-thymidine incorporation into BHK-21 and BHK/RSV cells was described. The results support previous observations that the NSP fraction contains a peptide growth prometing factor and a potent peptide growth inhibitor. The possible physiological role of the peptide growth inhibitor was discussed.