Julio Ludowieg

Colorimetric differentiation of hexosamines

Abstract A colorimetric method is introduced to differentiate glucosamine, galactosamine, and mannosamine. Direct evaluation of galactosamine in mixture with glucosamine was possible since galactosamine was essentially the only component responsible for the color of the reaction; the influence of glucosamine on the intensity of the color was negligible. The proposed method has been found highly satisfactory for the analysis of hexosamines in preparations of mucopolysaccharides, mucoproteins, and articular cartilage. The present report also includes observations on the reactivity of hexosamines with acetylacetone which has extended the usefulness of the Elson-Morgan reaction as a method of differentiating amino sugars. It also proposes the possible mechanism of the reaction.

The Composition of the Organic Component of Human Articular Cartilage: Relationship To Age And Degenerative Joint Disease

The collagen, mucopolysaccharides, sulphur, non-protein nitrogen, and non-collagenous protein content were determined in the articular cartilage of joints of the lower extremity its sixty patients. The results were analyzed with relation to the ages of the patients, the sites from which the cartilag

A method for analysis of amino sugars: specificity and mechanism of the reaction

Abstract Two methods for the analysis of amino sugars are presented. Ratios of the colorimetric values obtained with these two methods permit the preliminary characterization of several amino sugars and direct determination when they are in admixture with 2-amino-2-deoxy- d -glucose. The main features of the mechanism of the color reaction are outlined. Factors affecting the reproducibility of the Elson and Morgan analysis and the role of 2-methyl-pyrrole in the production of color are discussed.

The Mammalian Intervertebral Disc. The Collagen of Whale Fetal Nucleus Pulposus

The hydroxyproline content and total amount of imino acids of whale nucleus collagen are in the range of variability usually observed in other mammalian collagen and about the same as the values reported for the collagen isolated from human intervertebral disc.Salt and acid extracted collagen of fetal whale nucleus pulposus was obtained with the aid of pronase. Soluble collagen preparations were also obtained without the use of pronase. Insoluble collagen was purified as gelatin. The amino acid and carbohydrate composition of these preparations was essentially the same. The salt-soluble collagen of the fetal nucleus contains 2% neutral carbohydrate, present as galactose and glucose in 1.5:1 ratio, trace amounts of hexosamine and no uronic acid. The galactose to glucose ratio is, however, higher in gelatin preparations.Carboxymethylcellulose chromatography of neutral salt-extracted collagen (after pronase) primarily showed two chromatographic components corresponding to αl and β11 chains of rat tendon solu...