Biochimica et Biophysica Acta (BBA) - Mucoproteins and Mucopolysaccharides最新文献

An ultrafilterable but non-dialyzable glycopeptide fraction from normal human urine has been isolated and characterized. Its molecular weight was 2300 and its carbohydrate and amino acid composition was similar to those of some non-ultrafilterable glycopeptides recently described by the author and also to that described for purified blood group substances. The fraction was devoid of blood group A, B, H and Le^a activity.

• 1.

  1. A method is described for isolating flat pieces of transparent, unhydrolysed, protein-free chitin from the shell of the cuttlefish, Sepia officinalis L.

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  2. Chitin from the dorsal cover and the septa regions of the shell were found to be identical in physical and chemical properties. X-ray studies and, for the first time, infrared spectra, confirm that Sepia chitin is of the β-type.

Chemical analyses of human submaxillary salivary gland secretions from individuals of various blood types and blood group secretor statuses revealed a relationship between secretor status and the composition of total submaxillary glycoproteins. The dialyzed secretions from both secretors and non-secretors contained sialic acid, d-galactose, l-fucose, d-glucosamine, d-galactosamine, and protein. Half of the total hexose, one-third of the nitrogen-containing material and minor amounts of hexosamine were dialyzable. None of the sialic acid and fucose components was dialyzable.

The submaxillary saliva of secretors had a higher concentration of protein-bound carbohydrates than that of non-secretors and had about three times as much fucose. The ratio of sialic acid/fucose was 0.62±0.10 (S.D.) for secretors and 1.87±0.25 (S.D.) for non-secretors. There was a predictable relationship among the various carbohydrates in each type of secretion, and no major differences were observed among individuals of different blood types.

A study of the urinary excretion of mucopolysaccharides indicates a normal excretion of approx. 5–10 mg/24 h of a mixture of compounds. Although the major compounds normally excreted are the chondroitin sulfates (A, B, C), evidence is presented for the excretion of chondroitin, heparitin sulfate, and keratosulfate. The excretion appears to be somewhat greater in males and is increased around puberty. In the Marfan syndrome there is a two- to four-fold greater excretion but this is qualitatively similar to that for normal individuals. The mucopolysaccharide excreted in urine represents a small fraction relative to the amount metabolized in the body's connective tissue.

The specific activity of subcellular fractions of liver was determined at varying intervals after the intraperitoneal injection of [1-¹⁴C]glucosamine in mice. The deoxycholate-soluble portion of microsomal particulates was the most active. During the course of [¹⁴C]glucosamine incorporation into microsomal fraction in vivo, by way of uridine diphosphate-N-acetylglucosamine, the soluble ribonucleic acids isolated from the high-speed supernatant fraction were not labeled. Soluble ribonucleic acids from ribosomes were unlabeled also. Attempts to incorporate [¹⁴C]glucosamine into ribonucleic acids in vitro were also unsuccessful. A possible mechanism of carbohydrate addition to polypeptide chains is discussed.

Six lysosomal enzymes were found in the tissue homogenates of the stomach, duodenum, jejunum, ileum, cecum and colon of the rat and five of the enzymes were active in the same tissues of the pig. The concentrations of acid mucopolysaccharides in the tissue homogenates were measured. In the rat, they paralleled closely the specific activities for aryl sulfatase (aryl-sulfate sulfohydrolase, EC 3.1.6.1), β-glucuronidase (β-d-glucuronide glucuronohydrolase, EC 3.2.1.31) and β-galactosidase (β-d-galactoside galactohydrolase, EC 3.2.1.23), and in the pig that for aryl sulfatase. Compared to other segments of the tract, rat colon had the highest concentration of mucopolysaccharides and the highest specific activities for aryl sulfatase, β-glucuronidase and β-galactosidase. These three particulate enzymes from rat colon were released by osmotic shock and the solubilized enzymes had acid pH optima.