Identification and partial purification of chalone from human epidermis.

Abstract

SUMMARY Crude human skin extracts having tissue-specific mitotic inhibitory activity (chalone), were studied by ethanol precipitation and disc gel electrophoresis. Precipitates obtained at various ethanol concentrations were dialyzed, lyophilized and tested for their mitotic inhibitory activity. It was found that the greatest inhibitory activity was concentrated in the precipitate formed in 81% ethanol, the active principle being concentrated about 200 times. Proteins in crude extracts were separated by disc gel electrophoresis, and at least eight bands were identified. Groups of bands were extracted from the electrophoretic gels and tested for their mitotic inhibitory activity. Fraction II, containing two bands, had the highest activity. Disc gel electrophoretic analysis of the 81% ethane precipitate revealed only two major bands, one of which could also be found in fraction II of the crude extract. This protein band, which is present in both of the mitotic inhibitory samples, may represent the human epidermal chalone.