Studies in immunochemistry: The use of phenol and of alkali in the degradation of antigenic material isolated from Bact. dysenteriae (Shiga).

EARLIER work has shown [Morgan, 1937; Morgan & Partridge, 1939, 1, 2; 1940, 1; Partridge & Morgan, 1940] that the antigenic substance which is responsible for the dominant serological properties of the 'smooth' form of Bact. dysenteriae (Shiga) can be extracted from the micro-organism by means of diethyleneglycol. The properties of the antigenic complex were described in some detail and three major components were isolated and identified as polysaccharide, phospholipin and a protein or polypeptide-like substance. By the action of cold, neutral formamide, the phospholipin component was removed and there remained a complex of specific polysaccharide and the polypeptide-like component which still possesged powerful antigenic properties. The material dissolved in phosphate buffer (pH 7-5-8.0) solution containing 0Q85 % NaCl to yield a clear 0*2 % solution which could readily be passed through a sterile Berkefeld candle without appreciable loss. The protein component of the original antigenic complex on the other hand could be largely removed by the action of trypsin but the resulting polysaccharide-phospholipin complex possessed no significant antigenic capacity, as measured by the production of 'Shiga' agglutinins and precipitins. A number of other experimental procedures designed to separate the components of the antigenic complex were also mentioned. The material was shown to yield clear solutions in cold anhydrous formic acid and in concentrated solutions of phenol. From these solvents the antigenic material could be largely recovered by precipitation with alcohol or acetone. Details of our work with the latter solvent are now given with some observations on the action of alkali on the antigenic complex. EXPERIMENTAL