Process for the preparation of a new-type active substance selectively

Abstract

The invention involves isolating a food intake suppressant by subjecting blood serum to ultrafiltration transmitting up to a molecular weight of 30,000 daltons, partially evaporating the filtrate, removing the insoluble part from the concentrate obtained, adding trichloroacetic acid up to a concentration of 5 to 25 weight/volume percent to the liquid phase at a temperature of 0.degree. to 10.degree. C., removing the proteins precipitated, subjecting the obtained solution to chromatography on a gel with a void volume below a molecular weight of 4000 daltons, eluting with a solution of pH 6.0 to 7.0, concentrating the biologically active fractions, chromatographing again on a gel with a void volume below a molecular weight of 4000 daltons, fractionating by elution with water, lyophilizing the active fractions, dissolving the lyophilized fractions in a buffer of pH 8.1 to 8.2, adding trypsin and chymotrypsin to the solution in a substantially identical amount of 0.01 to 0.2 by weight as calculated for the total weight of the lyophilized product, subjecting the mixture to digestion at a temperature of 36.degree. C. to 39.degree. C., preferably with occasionally shaking from 20 to 30 hours, adding after the first 5 hours trypsin and chymotrypsin in a substantially half amount as calculated for the original enzyme quantity and continuing the digestion, then adding trichloroacetic acid to the reaction mixture up to a concentration of 4 to 6 weight/volume percent at a temperature between 0.degree. and 10.degree. C., keeping the mixture at a temperature between -15.degree. C. and 5.degree. C. for 1 to 24 hours, removing the insoluble part, subjecting the reaction mixture to chromatography on a gel with a void volume below a molecular weight of 4000 daltons, fractionating by elution with water and lyophilizing the biologically active fractions.