Abstract
The literature contains scattered references to the attraction of proteins for lipids. However, there are no statements in regard to any variations between normal and pathological conditions. Also no definite conclusions have been drawn as to the character of the attraction, that is, whether it is a physical or chemical union.
The problem was undertaken for a twofold purpose. It was hoped that an insight into the relationships between the various lipids and proteins might offer a method for differential diagnosis should there be characteristic variations in the amount of lipid associated with the albumin and globulin fractions. It was also thought that a more comprehensive study might throw some light on the type of association.
Blood plasma and edema fluids from cases having a possible lipemia were investigated; among these were cases of diabetes, nephritis, cirrhosis of the liver, carcinoma, and cardiac failure. Normal blood was taken for comparison. Fatty acids, lecithin, cholesterol (free and ester) and iodine numbers were determined in the extracted albumin and globulin fractions as well as in the whole fluid.
The proteins were removed in their respective fractions by means of ammonium sulfate, heat coagulated at the isoelectric point, and washed free from the salt. The fatty acids were determined by Bloor's oxidative method, the lecithin by oxidation and formation of the blue ammonium phosphomolybdate, the cholesterol by a modification of the Okey oxidative method, and the iodine numbers by Gibson's micro method.
Comparisons were made between the total lipid content and the lipid associated with the proteins, also the distribution of the latter between albumin and globulin was determined. Since the protein ratios are not consistent and the amounts of globulin and albumin are not equal, calculations on the basis of mg. percent do not give the true relation between the lipids and the respective protein lipid fractions.
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