The specific refraction increments of serum-albumin and serum-globulin

Abstract

(1) INTRODUCTION.THE refractive index of a protein solution is greater than that of pure water, and, according to the observations of Reiss [1904] and Robertson [1912], the difference between the refractions of the protein solution and the solvent is equal to the protein concentration in g. per 100 cc. of solution, multiplied by a constant. This constant is termed the specific refraction increment or the specific refraction of the protein.A critical account of the work of previous investigators on the refractions of the proteins in normal and in pathological sera has been published by Schretter [1926] who has drawn attention to the question as to whether the specific refraction increments show physiological or pathological variations. The results obtained by different observers show a wide range of variation in normal as well as in pathological sera, but further investigation is required in view of the risks of error due to the relatively low stability of the proteins and their association with lipins and other impurities.The first problem investigated in this work is the preparation of a purified solution of crystalline horse serum-albumin under conditions which minimise the risk of error due to alterations in the protein. The purity and stability of the preparations have beef tested by comparing their specific refraction increments after successive recrystallisations and after different periods of dialysis in accordance with the procedure adopted by Hopkins [1900] in establishing the individuality of egg-albumin by measurements of the optical rotation of the protein after successive recrystallisations.The second problem is the application of Donnan's theory of membrane equilibrium to measurements of the refractive indices of serum-albumin andserum-globulin solutions which have been enclosed in collodion membranes and dialysed against phosphate mixtures of well-defined hydrogen ion concentration. An experimental investigation of the effects of the unequal distribution of salts on refraction is of value in determinations of the specific refraction increment of globulin, which cannot be dissolved in the absence of electrolytes.

The Electrophoretic Analysis of Maternal and Fetal Plasmas and Sera

“…If sodium and potassium citrates are assumed to have the same molar tonicity, interpolation from the data of Heller and Paul (13) The specific refraction, k, is defined by equation 2. In addition to its dependence on the temperature, the wavelength, and the type of protein, k also varies with the nature of the buffer electrolytes due to the unequal distribution of the buffer ions between the two solutions when the latter are in a Donnan equilibrium (14). Moreover, owing to the presence of nitrogen-free constituents, such as lipids and carbohydrates, in many of the plasma proteins, a dry-weight determination of p, equation 2, yields a smaller value for k than a determination of protein nitrogen if the latter is multiplied by the conventional factor of 6.25.…”

Correction of stain variations in nuclear refractive index of clinical histology specimens

“…We develop a simple model that derives from the empirically well-established linear relationship between the change in refractive index of a protein or nucleic acid solution and their concentration or mass density. [25][26][27][28] This relationship was further validated by the work of Lee et al 29 and Popescu et al, 30 among others. Mathematically, it is described as…”

Studies on the Anomalous Viscosity and Flow-Birefringence of Protein Solutions

“…It has long been known that a molecule of ovalbumin, having a radius of 55.~ (Adair and Adair, 1940) unrolls into a surface fill of but 9.5A thickness (Astbury, Bell, Gorter, and van Ormondt, 1938). Some members of this group do it instantly (group B1) giving anomalous flow diagrams in the first instance, while others (group B~) require a considerable time to do so, and only give anomalous flow diagrams after the film has built itself up for half an hour or more.…”

“…Serum Globulin.--The globulin fraction of ox serum was prepared following the details in Adair and Robinson (1930), Elford and Ferry (1934), and the review of Cohn (1941). Repeated precipitation by half saturation with ammonium sulphate followed by dialysis through cellophane against weak phosphate buffer solution gave the euglobulin fraction, readily separable from the pseudoglobulins which remain unprecipitated in the supernatant liquid within the dialysis bag.…”