The Estimation of Proteins by the Precipitation Reaction

Abstract

1. The amount of crystallisable albumin in egg-white and the amount of total globulin in horse serum have been estimated by means of the precipitation reaction. The results are in good agreement with those obtained by other methods.2. For such estimations it appears advisable to use only antisera prepared against individual proteins.3. A description of the manufacture and the characteristics of the pure proteins used is appended.

The specificity of antisera against crystalline serum albumin

“…The ratios of precipitate nitrogen to antigen nitrogen obtained at the optimal point in the cases of A.S. 3075 A and of the concentrate of A.S. 3097 A were considerably lower than those found by Taylor et al (1934) and by Kabat & Heidelberger (1937) for crystalline horse-serum albumin and its homologous antiserum.…”

“…These values of the ratios for antisera obtained after one course of injections are probably less accurate than those published by Taylor et al (1934) and by Kabat & Heidelberger (1937), as, in some cases, the amount of nitrogen present was small. We are, however, convinced that experimental errors could not account for the differences between our determinations and those of previous authors.…”

“…The antibody contents of the antisera were determined by the method of optimal proportions (Dean & Webb, 1926;Taylor et al 1932), the results being recorded as optimal ratios which express the proportions by volume of antiserum and a standard 1 % solution of albumin found to yield the most rapid particulation. Ring tests were made by the addition of falling dilutions of antigen to undiluted antiserum, the reactions at the interface of the two fluids being read after the tubes had stood for 35 min.…”

The Demonstration of the Increase of Globulin in Diphtheria Antitoxins by the Precipitation Reaction

“…Titrations were performed by the method of Dean and Webb (1926) as described by Taylor, Adair and Adair (1932). The antigen-antibody ratios assigned to the experiments were the whole numbers nearest the mean of the ratios of the first two tubes to particulate; when the rates of particulation in the tubes on either side of the optimal one were the same, the ratio of the optimal tube was recorded, as in the horse serum series in Table I.…”

“…IN titrations of anti-horse sera against parallel dilutions of (a) normal horse serum, (b) horse serum globulin and (c) horse serum albumin, Taylor, Adair and Adair (1932) found that with some antisera a primary or main zone of optimal particulation (Dean and Webb, 1926) occurred in the (a) horse serum and (b) globulin series but was absent from the (c) albumin series: the precipitin was regarded as antiglobulin. With other anti-horse sera reactions were seen in all three series: presumably these antisera contained both antiglobulin and antialbumin.…”