GB742594A - Preparation and purification of human serologically compatible protein derivatives for use as plasma extenders and products produced thereby - Google Patents

Abstract

Protein derivatives are prepared by reacting a human serologically compatible protein with an anhydride or chloride of an aliphatic polycarboxylic acid in an aqueous medium in which the pH is maintained between 6 and 12, thereafter, while maintaining the temperature of the mixture above 5 DEG C., adjusting the acidity of the reaction mixture to a pH of below 6 and approximating the isoelectric point of the protein derivative to precipitate this derivative as a coagulum, separating the coagulum from the reaction mixture and further working up the coagulum to remove therefrom any remaining incompletely reacted protein and any noncoagulated reaction products by reprecipitation of the coagulum from aqueous solution at the isoelectric point of the protein derivative, e.g. with the aid of sodium chloride, methanol, ethanol, isopropanol or acetone. Suitable compatible proteins are gelatin, human serum albumin, human globulin and human globin, and especially gelatin degraded to an average molecular weight in the range of 15,000 to 36,000. Specified polycarboxylic acid reactants are succinic, citraconic, itaconic, aconitic and maleic anhydrides and succinyl and fumaryl chlorides. The protein derivatives may be used as blood plasma extenders (see Group VI). In typical examples: (1) powdered succinic anhydride is slowly added at 36 DEG C. to a stirred aqueous solution of gelatin, the pH being maintained at 8.5 to 10 by regular additions of aqueous NaOH; the pH of the reacted mixture is then reduced to 2.7 by means of HCl and, on settling, an immiscible bottom layer of oily protein derivative forms which is separated and dissolved in distilled water; the pH of the solution is adjusted to 2.5-3.0 and sodium chloride added to reprecipitate the protein derivative which may be further purified by dialysis to remove entrained salt; (7) fumaryl chloride is reacted with aqueous gelatin following the method of (1), the reacted mixture is then acidified to pH 2.5 and the precipitated protein purified as before. The mother liquors from the first precipitation of protein derivative may be cooled to precipitate other protein products of lower molecular weight. Specifications 649,544 and 649,545 are referred to.ALSO:Blood plasma extenders comprise isotonic solutions of protein derivatives prepared by reacting human serologically compatible proteins with an anhydride or chloride of an aliphatic polycarboxylic acid (see Group IV(b)). Specified reactants are gelatin, human serum albumin, human globulin and human globin and succinic, citraconic, itaconic, aconitic and maleic anhydrides and succinyl and fumaryl chlorides. Specifications 649,544 and 649,545, [both in Group IV(b)], are referred to.