Studies on gastric mucoproteins. The production of radioactive mucoproteins by pig gastric mucosal scrapings in vitro

1. Optimum conditions, including the effect of media of different pH values, were determined for the incorporation of radioactive precursors into mucoproteins by pig gastric mucosa in vitro. 2. Mucosal scrapings incorporated radioactivity from [U-¹⁴C]-glucose and from [G-³H]threonine or [G-³H]serine solely into the carbohydrate and protein portions respectively of the mucoprotein molecules. 3. Of the radioactive mucoprotein 22% was water-soluble and up to 80% of the remainder was soluble in other solvents. 4. Pronase was the most successful proteolytic enzyme tested for making the mucoprotein water-soluble, up to 94% dissolving after digestion. 5. The Pronase digestion products of the mucoproteins were separated from protein by equilibrium-density-gradient centrifugation in a CsCl gradient. 6. These Pronase-digested mucoproteins were further fractionated on Sepharose 4B and the isolated fractions analysed by chemical and sedimentation-velocity methods. 7. Pronase digestion and solvent extraction of mucosal scrapings labelled with ¹⁴C in the carbohydrate and ³H in the protein showed that one type of mucoprotein was the only non-diffusible biosynthetic product of the scrapings in vitro, and that this mucoprotein was the only mucoprotein constituent of the water-soluble and water-insoluble mucus.     

Isolation and composition of a glycoprotein from lamb gastric mucosa]

A glycoprotein is isolated from lamb gastric mucosa. It is purified first by reduction with dithiothreitol and then by chromatography on CM-Sephadex followed by gelfiltration on Sephadex G-75. Its homogeneity is investigated by disc electrophoresis, immunoelectrophoresis, analytical ultracentrifugation and identification of the carboxy- and amino-terminal amino acids. This glycoprotein contains 56 p. cent carbohydrates, consisting of N-glycolyneuraminic acid, fucose, galactose, and hexosamines. Hexosamines and galactose are in equimolar ratio ; galactosamine and glucosamine in the ratio 1 :2. The amino acid composition shows that threonine, serine and proline account for half of the amino acid residues. The cysteine origin and function are discussed.     

Studies on gastric mucosal IgA: separation of immunoglobulin rich fraction from gastric mucoproteins.

Human gastric mucosal scrapings were subjected to fractionation on an isopycnic CsCl gradient. Immunoglobulin A was found between the 5th and 10th ml from the top of the tube. (Total volume 12ml). After two-fold fractionation the combined IgA containing fraction accounted for 4%–7% of the total carbohydrate content of the original gastric mucosal scrapings. Gas liquid chromatography of sugars showed the fraction to be enriched in Mannose and N-Acetyl glucosamine. The total carbohydrate content of the material was 5.5%–7% by weight. Immunodiffusion against specific anti Secretory component serum failed to demonstrate the presence of the secretory component in this fraction. It is concluded that gastric mucosal IgA, which appears to differ from a typical sIgA in lacking the characteristic secretory component activity, can be separated from the carbohydrate-rich gastric mucoproteins by CsCl fractionation. This indicates the absence of covalent bonding between IgA and the mucoproteins of gastric mucus.     

Conformational changes in gastric mucoproteins induced by caesium chloride and guanidinium chloride

1. Caesium chloride and guanidinium chloride were shown to cause conformational changes in the high-molecular-weight mucoprotein A of water-soluble gastric mucus with no change in molecular weight. 2. Increasing concentrations of CsCl decrease the viscosity of the mucoprotein bringing about a transition which is essentially complete in 0.1m-CsCl. The shear-dependence of viscosity of the mucoprotein is abolished by low concentrations of CsCl. The normally highly expanded molecule becomes contracted in CsCl to a molecule having the same symmetry but a smaller volume and decreased solvation, in keeping with an increased sedimentation coefficient (18.7S-->33S). 3. This contracted form does not revert to the native conformation on removal of the CsCl. 4. A mechanism is discussed in terms of the effect of the Cs(+) and Cl(-)ions on water structure and the water-mucoprotein interaction. 5. Guanidinium chloride causes the CsCl-treated material to expand, in keeping with a decrease in s(0) (25,w) (33S-->26S). This is analogous to the known unfolding effect of guanidinium chloride on proteins and suggests that guanidinium chloride solubilizes groups involved in stabilizing the contracted structure. Removal of the guanidinium chloride results in a limited aggregation of four mucoprotein molecules. 6. These results show that caution must be exercised before interpreting the physical properties of mucoproteins which have been treated with CsCl and/or guanidinium chloride.     

Antigenic characteristics and various biological properties of glycoprotein from Neisseria meningitidis of serological group A]

It was shown that the antigen determining the group specificity of meningococcus belonging to serological group A was of mixed polysaccharide-protein nature. Carbohydrate component is responsible for the interaction with the group-specific antibodies in this antigen. Glycoprotein can be isolated both from the cells and from the culture fluid where it passes during the N. meningitidis cultivation in fluid nutrient medium. The described antigen possesses no properties of endotoxin.     

Antigenic activity of Bordetella pertussis during cultivation in liquid nutrient media]

The authors studied the antigenic activity of Bordetella pertussis during stab cultivation. For the first time there were revealed changes (oscillations) of antigenic activity: formation of 3 peaks of which the middle was the highest. A possibility of improving the quality of pertussis vaccine by using biomass at the height of the peak was experimentally founded.     

The biochemical aspects of blood group antigens]

The biochemical aspects of the immunodominant structures of blood groups antigens are mainly restricted to the following: ABH and Lewis in secretory fluids or on the red blood cells; P system (P1, P, Pk antigens); MN antigens and related; Tn and Tn antigens; Some hypothesis may be put forward for the I, i antigens. Many other antigens seem to be on the dependence of interactions between proteins and lipids of the red cell membrane; such immunodominant structures are not yet known. Except for the ABH and Lewis groups, the biosynthesis pathways are at present unclear.     

Characterization of gastric mucoproteins isolated by equilibrium density-gradient centrifugation in caesium chloride

1. The mucoprotein from pig gastric mucus has been purified by equilibrium centrifugation in a CsCl gradient. 2. This procedure removes the non-covalently bound protein, which is closely associated with the mucoprotein and not easily removed from it by gel filtration. 3. The purified mucoprotein is separable by gel filtration into a high-molecular-weight mucoprotein A (mol.wt. 2.3×10⁶) and a low-molecular-weight mucoprotein B/C (mol.wt. 1.15×10⁶). 4. These two mucoproteins have the same chemical analysis namely fucose 11.3%, galactose 26%, glucosamine 19.5%, galactosamine 8.3% and protein 13.6%. 5. Mucoprotein A contains 3.1% ester sulphate. 6. These mucoproteins are isolated without enzymic digestion and have a higher protein content than the blood-group-substance mucoproteins from proteolytic digestion of gastric mucus. Detailed amino acid analysis shows that the extra protein in the non-enzymically digested material is composed of amino acids other than serine and threonine. 7. Mucoproteins A and B/C contain respectively 130 and 9 half-cystine residues per molecule of which about 78 and 6 residues are involved in disulphide linkages. 8. Cleavage of these disulphide linkages by mercaptoethanol splits both mucoproteins into four equally sized subunits of mol.wt. 5.2×10⁵ for mucoprotein A and 2.8×10⁴ for mucoprotein B/C. 9. The sole N-terminal amino acid of mucoprotein A is aspartic acid, whereas mucoprotein B/C has several different N-terminal amino acid residues.     

Branched blood group A-active fucolipids of hog gastric mucosa.

New complex glycolipids have been extracted from hog gastric mucosa with the mixture of 0.4 M sodium acetate in methanol/chloroform/water. Three A-active fucolipids having branched carbohydrate chains have been purified from this extract. The postulated structures of these glycolipids are based on the results of partial acid hydrolysis, oxidation with periodate and chromium trioxide, and permethylation studies.     

Antigenic structure of Rickettsia of the tick-borne spotted fever group isolated in the Armenian SSR]

The authors present data concerning the study of the antigenic properties of rickettisa of the tick-borne spotted fever group isolated from the Ixodes ticks in the Armenain SSR. In order to determine the species of the isolated strains a method of serological identification of rickettsia in the complement fixation reaction with the species-specific immune sera of albino mice was used. The results obtained permitted to refer the Armenia-74, No. 11, 29, and 57 species to the R. sibricia species.     

The nature of ABH blood group antigens in human gastric secretion

The origin of blood group ABH activity in human gastric content was investigated. Dialyzed and lyophilized samples of ten individual gastric secretions were assayed for ABH antigen under various conditions. The native activity persisted in delipidated residue of the respective secretions, but was completely missing in the lipid extracts of the analyzed samples. The alkaline degradation of the native and delipidated samples led to total loss of blood group activity of the analyzed materials, but no effect on A-active glycosphingolipid was evolved. Purified glycolipid portion of the lipid extract was lacking ABH activity and was shown to have distinct composition. This fraction contained only glyceroglucolipids and neither sphingosine nor other carbohydrates were present. On the basis of blood group activity assays of the native, delipidated, alkaline degraded samples and also on glycolipid analysis it was established that the ABH blood group activity of stomach secretion originated entirely from the glycoprotein portion of these samples.     

Antigenic composition of adenovirus hexons]

Quantitative relations between the group-specific and the type-specific components of the hexons of adenovirus type 2 and 5 were studied by means of FITC-conjugated Fab-fragments of antibodies directed against type 2 and type 5 hexons. From the sedimentation constant of the complexes of hexons and Fab in the region of excess of Fab we conclude that there are at least 20 determinants on the hexon. Half of these are type-specific and the others are group-specific. Both components of the type 2 hexon consist of equal parts of carbodiimide sensitive and carbodiimide resistent determinants.     

Antigenic activity of a gamma-ray inactivated, concentrated, purified cultured antirabies vaccine]

Concentrated purified cultural rabies vaccine inactivated with gamma-rays caused in intramuscular injection (2 ml twice at an interval of 23 and 21 days) production of virus-neutralizing antibodies both in experiments on animals and in the vaccinated volunteers in titres not below those obtained in persons given a complete course of cultural rabies vaccine inoculations. No untoward reactions occurred.