Changes to Mucins in Uninvolved Mucosa and at the Tumour Site in Gastric Adenocarcinoma of Intestinal Type

1998 ◽  
Vol 94 (1) ◽  
pp. 87-99
Author(s):  
R. L. Sidebotham ◽  
N. K. Dhir ◽  
J. B. Elder ◽  
J. Spencer ◽  
M. M. Walker ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gastric Mucosa ◽  
Carbohydrate Chain ◽  
Intestinal Type ◽  
Amino Acid Residues ◽  
Mucous Cells ◽  
Tumour Site ◽  
Mucin Histochemistry ◽  
Gastric Type ◽  
Carbohydrate Chains

1. Mucin histochemistry is markedly altered in the stomach in intestinal-type adenocarcinoma. To increase understanding of these changes we have examined the content and distribution of carbohydrate in mucus glycopolypeptides isolated from non-malignant antrum, and from the uninvolved gastric mucosa and tumour site of patients with this disease. 2. The content of carbohydrate declined by 12.6% (P = 0.02) in mucus glycopolypeptides from uninvolved gastric mucosa when compared with those from non-malignant antrum, and by a further 25.4% (P < 0.001) in mucus glycopolypeptides from the tumour site. The first of these changes was accompanied by a significant decrease in the number of carbohydrate chains/1000 amino acid residues, and a significant increase in the number of monosaccharide units in each carbohydrate chain. The second of these changes was accompanied by significant decreases in both the number of carbohydrate chains/1000 amino acid residues, and in the number of monosaccharide units in each carbohydrate chain. 3. The number of sulphated monosaccharide units/100 carbohydrate chains increased from a mean of 7.2 in mucus glycopolypeptides from non-malignant antrum to a mean of 27.2 (P < 0.001) in preparations from uninvolved gastric mucosa and 22.7 (P < 0.001) in preparations from the tumour site. 4. Evidence is presented that these structural changes to mucus glycopolypeptides from the malignant stomach are due to an abnormal mucin biosynthesis by metaplastic goblet cells and/or immature gastric-type mucous cells within the uninvolved mucosa, and immature mucous cells at the tumour site.

Influence of Blood Group and Secretor Status on Carbohydrate Structures in Human Gastric Mucins: Implications for Peptic Ulcer

1995 ◽  
Vol 89 (4) ◽  
pp. 405-415 ◽  
Author(s):  
R. L. Sidebotham ◽  
J. H. Baron ◽  
J. Schrager ◽  
J. Spencer ◽  
J. R. Clamp ◽  
...  
Keyword(s):  
Peptic Ulcer ◽  
Amino Acid ◽  
Blood Group ◽  
Average Length ◽  
Amino Acid Residues ◽  
Secretor Status ◽  
Increased Risk ◽  
The Mean ◽  
The Difference ◽  
Carbohydrate Chains

1. The content and distribution of carbohydrate was examined in mucus glycopolypeptides from human antral mucosae. 2. The mean amount of carbohydrate per 1000 amino acid residues was found to be similar in glycopolypeptides with A, B or H activity. It was slightly, though significantly, less in glycopolypeptides lacking these determinants, because carbohydrate chains were of a shorter average length than in the A-, B- or H-active preparations. This difference was reflected in the sizes of oligosaccharide—alcohols released from representative glycopolypeptides with alkaline borohydride. 3. Differences between A-, B- or H-active and non-secretor glycopolypeptides in terms of the mean number of carbohydrate chains per 1000 amino acid residues were found to be small, and without significance. 4. The average number of peripheral monosaccharide units per 1000 amino acid residues was greater in A-active than in H-active, and least in non-secretor, glycopolypeptides. This order was reversed for monosaccharide units incorporated into skeletal (core plus backbone) structures. The difference in each case was statistically significant. 5. These findings suggest that the increased risk of peptic ulcer associated with blood group O and non-secretor status is unlikely to be attributable to an inherent deficiency in the protective mucus layer, linked to differences between mucins that are associated with A, B or H activity. Other hypotheses linked to infection with Helicobacter pylori are examined.

Substrate Recognition by Vitamin K-Dependent Carboxylase

1987 ◽  
Vol 57 (01) ◽  
pp. 017-019 ◽  
Author(s):  
Magda M W Ulrich ◽  
Berry A M Soute ◽  
L Johan M van Haarlem ◽  
Cees Vermeer
Keyword(s):  
Amino Acid ◽  
Vitamin K ◽  
Substrate Recognition ◽  
Bovine Liver ◽  
Amino Acid Residues

SummaryDecarboxylated osteocalcins were prepared and purified from bovine, chicken, human and monkey bones and assayed for their ability to serve as a substrate for vitamin K-dependent carboxylase from bovine liver. Substantial differences were observed, especially between bovine and monkey d-osteocalcin. Since these substrates differ only in their amino acid residues 3 and 4, it seems that these residues play a role in the recognition of a substrate by hepatic carboxylase.

Statistical Force-Field for Structural Modeling Using Chemical Cross-Linking/mass Spectrometry Distance Constraints

2018 ◽  
Author(s):  
Allan J. R. Ferrari ◽  
Fabio C. Gozzo ◽  
Leandro Martinez
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Force Field ◽  
Protein Structures ◽  
Protein Structure Determination ◽  
Structural Modeling ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Distance Constraints ◽  
Chemical Cross Linking

<div><p>Chemical cross-linking/Mass Spectrometry (XLMS) is an experimental method to obtain distance constraints between amino acid residues, which can be applied to structural modeling of tertiary and quaternary biomolecular structures. These constraints provide, in principle, only upper limits to the distance between amino acid residues along the surface of the biomolecule. In practice, attempts to use of XLMS constraints for tertiary protein structure determination have not been widely successful. This indicates the need of specifically designed strategies for the representation of these constraints within modeling algorithms. Here, a force-field designed to represent XLMS-derived constraints is proposed. The potential energy functions are obtained by computing, in the database of known protein structures, the probability of satisfaction of a topological cross-linking distance as a function of the Euclidean distance between amino acid residues. The force-field can be easily incorporated into current modeling methods and software. In this work, the force-field was implemented within the Rosetta ab initio relax protocol. We show a significant improvement in the quality of the models obtained relative to current strategies for constraint representation. This force-field contributes to the long-desired goal of obtaining the tertiary structures of proteins using XLMS data. Force-field parameters and usage instructions are freely available at http://m3g.iqm.unicamp.br/topolink/xlff <br></p></div><p></p><p></p>

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