PHOTOMETRIC MICRODETERMINATION OF HUMAN GAMMA GLOBULIN. I. DEVELOPMENT OF A QUANTITATIVE FLOCCULATION-NINHYDRIN PROCEDURE 1

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Abstract
A simple accurate photometric microprocedure for the quantitative detn. of electrophoretically pure gamma globulin (Conn''s Fraction II) in the range of 100 to 1000 [mu]g. of protein, is described. The principle of the method involves the quantitative flocculation from soln. of the gamma globulin with a cephaiin-cholesteroi emulsion in the presence of Hayem''s soln. and detn. of the protein content of the ether-washed precipitate photometrically with the ninhydrin reaction, all in the same tube. The factors which influence the quantitative flocculation, ninhydrin reaction, e.g., pH, temp., time, concn. of the reagents, etc., were carefully studied and controlled. Subtractions of gamma globulin gave results which were identical with those obtained with the original whole Fraction II. The effect of the presence of each of Cohn''s other protein fractions (Method 6) which constitute whole plasma, was investigated for their effect on the quantitative detn. of gamma globulin. Only those fractions which are rich in fibrinogen, beta globulin or beta lipoprotein interfere.