Cytoplasmic 3H-arginine polypeptides of Ehrlich ascites tumour cells.
Low molecular weight ninhydrin positive peptide fractions of the Ehrlich tumour cell cytoplasm were isolated and characterized. After preliminary gel filtration of the cytoplasm on Sephadex G-25 column, the peptide mixture was fractionated on cationic exchanger SP-Sephadex C-25 column and eluted with increasing pH gradient. Five peaks were obtained. Only the first peak contained sugar component. All five peptides were studied with respect to molecular weight, isoelectric point and electrophoretic homogeneity. The cytoplasm of Ehrlich tumour cells contains one peptide of acidic (pI-5.0), two slightly basic (pI-7.7 and pI-7.7) and two strongly basic nature (pI-8.7 and pI-8.9). Molecular weights varied from 8 500 to 18 500 daltons. The origin of these peptides is briefly discussed.