Fifty three individual gastric aspirations were eluted on Bio-gel PI50. Improved methods of separation and analysis provided a tolerably pure non-retarded fraction. The carbohydrate component showed a basic structure common to all glycoproteins comsposing the non-retarded fraction. It showed the following quantitative relationship: Galactose : Glucosamine : Galactosamine

1. The sugars and amino sugars of hydrolysates of gastric secretion were determined by gas-liquid chromatography. 2. All the gastric aspirations examined showed on hydrolysis the presence of fucose, galactose, mannose, glucose, galactosamine, glucosamine, N-acetylneuraminic acid and sulphate. 3. Galactose and glucosamine were always found in equimolar amounts, but the galactose/galactosamine ratio in different aspirations was 2:1, 3:1, 4:1 or 5:1. Repeated gastric aspirations of each subject examined showed constant ratios of these carbohydrate components. 4. Fucose and sialic acid appear to be related to glucosamine and galactosamine respectively. 5. The carbohydrate components of extracts from the mucous glands of the body mucosa and antrum did not differ from those of gastric secretion.

SUMMARY The isolation of the principal glycoprotein from human gastric aspirates and the determination of its carbohydrate and amino acid composition is described.Ninety-nine individual gastric aspirates were investigated. Eighty-two were eluted on Bio-gel P150 and the carbohydrate and amino acid composition of each non-retarded fraction was determined. Fifteen of these non-retarded fractions were chromatographed again on Ecteola cellulose. Seventeen aspirates were precipitated with cetylpyridinium chloride. The carbohydrate, amino acid, and sulphate contents of the subfractions eluted on Ecteola cellulose and cetylpyridinium chloride precipitates were determined.The results suggest that the non-retarded fractions are composed of glycoproteins with a constant basic composition but polydisperse with respect to the sulphate contents and the terminal sugar residues which are associated with blood group specificity. It was found possible to correlate and identify in chemical terms the blood group specificity of all the glycoproteins investigated. No significant differences were detected between the carbohydrate and amino acid composition of each of the non-retarded fractions, the subfractions eluted on Ecteola cellulose, and the cetylpyridinium chloride precipitates. The sulphate content of the isolated glycoproteins was found to vary between zero and a sulphate: glucosamine ratio of 2:3. The subfractions of Ecteola cellulose showed that 20-50% of the glycoproteins were sulphated. The data also suggest that the isolated glycoprotein is the principal carbohydrate-containing fraction of the gastric secretion as it contained 68-96% of the total carbohydrate content of the gastric aspirates investigated.Aspirated gastric secretions contain gelatinous lumps which can be packed down by centrifugation. The deposit forms the so-called 'visible' mucus as distinct from the 'soluble' mucus contained in the supernatant (Babkin, 1950).A recent paper from this laboratory described the isolation of a glycoprotein from the supernatant of gastric aspirates (Schrager and Oates, 1970). That paper also reported the carbohydrate and amino acid composition of the isolated glycoprotein and its partial characterization. The investigation described in the present paper is an extension of previous studies. Its purpose was the isolation of the glycoprotein from the whole gastric aspirate containing both the 'soluble' and 'visible' mucus, using gel chromatography; the isolation of the glycoprotein by a method unrelated to gel chromatography; and the study of the degree of sulphation and the

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The isolation of the glycoprotein composing the deposit, the ‘visible’ mucus, of centrifuged gastric aspirations is described and its composition and some structural features pointed out. No differences could be detected between the glycoprotein of the supernatant and that of the deposit. Conditions affecting the distribution of the glycoprotein between the supernatant and deposit are discussed.