Extraction, Purification and Preliminary Characterisation of the Epidermal Chalone:

Pig skin powder, prepared in different ways, was extracted with water and fractionated for the purification of epidermal chalone. Various fractionation methods were tried, e.g. ethanol fractionation, ion exchange chromatography, gel filtration and column electrophoresis. The most effective method proved to be ethanol fractionation followed by column electrophoresis at pH 3 and then dialysis. Ethanol fractionation of a cod skin powder extract is also reported. Although the biological tests involving depression of epidermal mitotic activity did not result in exact evaluation of the fractions, they did indicate that the active principle of crude pig skin extracts was purified about 2,000 times. Characterisation studies show that the chalone obtained from pig skin is a protein or a glycoprotein which is stable at low pH, and has an isoelectric point between 5.2 and 6.0. The most purified material shows in the ultracentrifuge a symmetrical peak corresponding to a molecular weight of 30,000 to 40,000. It may still be heterogeneous.