Studies on the possible presence of the uratebinding alpha-1-alpha-2 globulin in human erythrocytes.

Recent investigations indicate that urate is partly transported through the erythrocyte membrane by a process which might involve a protein-carrier system. In the present work erythrocyte proteins have therefore been studied with special emphasis on the possible presence of the urate-binding alpha-1-alpha-2 globulin. The erythrocytes were destroyed by freezing and thawing and the "ghosts" subsequently treated with desoxycholate or ultrasound. The three different protein fractions obtained were subjected to anion exchange chromatography on DEAE-Sephadex columns according to the procedure employed for isolating the urate-binding alpha-1-alpha-2 globulin. In this way 10-14 different non-hemoglobin protein zones could be distinguished by vertical starch gel electrophoresis. None of these proteins, however, seemed to be identical to the urate-binding alpha-1-alpha-2 globulin.

The Urate-Binding Alpha1 -2 Globulin: Isolation and Characterization of the Protein from Human Plasma.

The urate-binding α1-2 globulin has been isolated from human plasma in a highly purified state. The isolation procedure was based upon anion exchange chromatography of the plasma macromolecular fraction on DEAE-Sephadex columns followed by ammonium sulphate precipitations and preparative polyacrylamide gel electrophoresis. The urate-binding α1-2 globulin is a rod-shaped glycoprotein with a molecular weight of 67000 as determined by dodecyl sulphate polyacrylamide gel electrophoresis and an isoelectric point of pH 4.6. In the presence of 6 N urea and mercaptoethanol respectively the protein does not split into subunits indicating that it might represent a single polypeptide chain. The urato-binding α1-2 globulin contains 12.1% of carbohydrates including galactose, mannoso, galactosamine and sialic acid. The amino acid composition of the protein does not differ significantly from what is found in other plasma proteins except for the presence in automatic amino acid analysis of an hitherto unidentified compound. Further work is required in order to determine the number of binding sites for uric acid on the protein molecule.-The urate-binding α1-2 globulin does not seem to be identical to any previously characterized protein from human blood.

Genetic studies in primary gout. Investigations on the plasma levels of the urate-binding alpha 1-alpha 2-globulin in individuals from two gouty kindreds.

The plasma levels of the urate-binding alpha(1)-alpha(2)-globulin, as determined by its urate-binding capacity, have been recorded in 19 individuals from two gouty kindreds. A significantly reduced binding capacity, accounting for 13-30% of the mean value obtained in healthy, unrelated control subjects, was found in all cases of gout and in the single case of essential hyperuricemia included in the present study. In addition, six apparently healthy members of one of these kindreds also exhibited this characteristic. The distribution of the characteristic in three subsequent generations from this kindred further supported the hypothesis that the reduced binding capacity was inherited as an autosomal trait for which affected subjects were heterozygous. Based on the present observation, the mechanisms of inheritance in primary gout are discussed with special emphasis on the possible cooperation of genetic and environmental factors.

The presence of vitamin A in human tryptophan-rich prealbumin.

Human tryptophan-rich prealbumin has been isolated from serum and its homogeneity evaluated by immunoelectrophoresis and polyacrylamide-gel electrophoresis. The green fluorescence of the protein when exposed to ultraviolet light was shown to be due to the presence of vitamin A. It is suggested that trytophanrich prealbumin represents the hitherto unknown specific transport protein for vitamin A.