The Role of Serine in the Linkage of Heparin to Protein

Triglyceride lipases in acute hepatitis

Two triglyceride lipases in postheparin plasma, the lipoprotein lipase (LPL) and the hepatic triglyceride lipase (H-TGL) were separated by heparin-sepharose affinity chromatography and studied in controls and patients during the course of acute hepatitis. All three patients had increased content of triglycerides in the low density lipoproteins, and two of them had hypertriglyceridemia. Low activities of both lipases were found in the acute stage of the disease in all three patients. Concomitantly one of the patients had absolute low lecithin: cholesterol acyltransferase (LCAT) activity, and in the two other patients a relative LCAT deficiency was present. The increased content of triglycerides in LDL that may be found in liver disease, may not only be due to low H-TGL and LPL, but also LCAT deficiency.

Proteoglycans of soluble fraction of mouse mastocytoma

Proteoglycans have been isolated from a high speed supernatant fraction of a mouse mastocytoma by procedures which should minimize alteration of the native protein-polysaccharide molecule. The methods used include in vivo labeling proteoglycans with 35S-sulfate, 3H-leucine and 3H-lysine, centrifugation of the tumor homogenate at 105,000 g, cetylpyridinium fractionation of the supernatant, and further purification of some of the fractions obtained by DEAE-cellulose column chromatography, gel filtration on Sepharose 4B and cellulose acetate electrophoresis. Two major sulfated proteoglycans were obtained, one containing keratan sulfate-like material (KSP-S), the other a heparin-like polymer (HP-S). The presence in HP-S of a compound similar to heparin was confirmed by its digestibility with flavobacterium heparinase. HP-S contained about 4 per cent protein. Glycine was the predominant amino acid, and serine did not appear to be involved in the peptide-carbohydrate linkage. The proteoglycan present in HP-S appeared to be homogeneous when examined using cellulose acetate electrophoresis. KSP-S was found to contain sialic acid and its protein content was significantly higher than that of HP-S. Glutamic and aspartic acids were the most abundant amino acids in KSP-S.

Preparation of carcinoembryonic antigen (CEA) containing significantly increased amounts of galactose and galactosamine

CEA was prepared by combined isoelectric precipitation, ultrafiltration and column chromatography under controlled conditions of pH. The resulting immunologically active materials were higher in carbohydrate (85-87%), N-acetyl galactosamine (10-11.5%) and galactose (28-32%) content than that previously reported. Differences in amino acid yield were also noted; the concentrations of aspartate, serine, glycine and alanine being higher and that of lysine, histidine, arginine, proline, valine, isoleucine, leucine and tyrosine were lower than that reported for CEA prepared by previous methods. The tumor tissues for CEA extraction were obtained from two Group O Rh positive deceased. Neither preparation showed Group A or B activity as measured by hemagglutination inhibition. It is suggested that the method of purification influences the carbohydrate and amino acid yields.