Cytoplasmic Proteins^*: A Partial Physical and Chemical Characterization of the Cytoplasmic Proteins

Extracts prepared from two rat fibrosarcomas were examined by both physical and chemical procedures. The amount of nitrogen and phosphorus extracted and the nature of the electrophoretic patterns of the extracts were independent of the extraction media employed. Three clearly defined electrophoretic components were observed in the methylcholanthrene- and four in the benzpyrene-induced tumor extracts. The number of electrophoretic components, their mobilities, and their relative compositions were readily reproducible from preparation to preparation, and no changes in the electrophoretic patterns were detected when the extracts were stored at -25° C. for 2 months. If kept at 0° C., the extracts were most stable at pH 7.8–8.0.

Electrophoretic patterns taken on plasma of normal and tumor-bearing rats were similar, except that for the latter animals a slight γ-globulin decrease was indicated. The relative compositions of the electrophoretic components found in the tumor extracts and in normal rat plasma were dissimilar, but several of the components had similar electrophoretic mobilities in both patterns.

The apparent complexity of the extracts and the incomplete electrophoretic resolution obtained suggest that other components are associated with each peak. Fractions were prepared by ammonium sulfate precipitation, and these were electrophoretically examined.