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Comparative studies on intrinsic factor and cobalophilin in different parts of the gastrointestinal tract of the pig.
Biochem J. 1978 Sep 01; 173(3):705-12.BJ

Abstract

The vitamin B(12) binders in the pig pyloric mucosa gastric and intestinal juice from the upper gastrointestinal tract were fractionated into only two molecular forms, classified as intrinsic factor and cobalophilin. The unsaturated vitamin B(12)-binding power due to cobalophilin was lower in the intestinal than in the gastric juice. Electrofocusing revealed that intrinsic factor and cobalophilin in the intestinal juice contained more of the ;neutral'-type isoproteins, and the suggestion is made that this is due to enzyme activity. The gastric-juice intrinsic factor contained more acidic isoproteins, which supports the hypothesis that carbohydrate is added on to the polypeptide chain of this protein before it is secreted into gastric juice. The gastric- and intestinal-juice cobalophilins, studied also by electrofocusing, differed from that of pyloric mucosa and they appeared to be of salivary origin. With regard to molecular dimensions there was no significant difference between the intrinsic factors and cobalophilins from all sources studied. All cobalophilins had molecular weights by the formula of Svedberg of approx. 92500, Stokes radii of 4.62nm and sedimentation coefficients of 5.15S. The corresponding values for the intrinsic factors were 63600, 3.57nm and 4.38S. In addition, the intrinsic factors exhibited similar avidities for binding to the solubilized ileal intrinsic-factor receptor. Also the intrinsic factors and cobalophilins, irrespective of their source, bound to the analogous specific xenoantibodies with the same avidity. The present results demonstrate that intrinsic factor remains practically unaltered during its passage through the proximal intestine and render unlikely the speculations made about the presence of an endogenous binder for intrinsic factor as well as the existence of a ;pancreatic intrinsic factor'. In addition, they are compatible with the theory that the interference by undegraded cobalophilin may be the reason for the abnormal vitamin B(12) absorption observed in patients with pancreatic insufficiency.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

708368

Citation

Marcoullis, G, et al. "Comparative Studies On Intrinsic Factor and Cobalophilin in Different Parts of the Gastrointestinal Tract of the Pig." The Biochemical Journal, vol. 173, no. 3, 1978, pp. 705-12.
Marcoullis G, Merivuori H, Gräsbeck R. Comparative studies on intrinsic factor and cobalophilin in different parts of the gastrointestinal tract of the pig. Biochem J. 1978;173(3):705-12.
Marcoullis, G., Merivuori, H., & Gräsbeck, R. (1978). Comparative studies on intrinsic factor and cobalophilin in different parts of the gastrointestinal tract of the pig. The Biochemical Journal, 173(3), 705-12.
Marcoullis G, Merivuori H, Gräsbeck R. Comparative Studies On Intrinsic Factor and Cobalophilin in Different Parts of the Gastrointestinal Tract of the Pig. Biochem J. 1978 Sep 1;173(3):705-12. PubMed PMID: 708368.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparative studies on intrinsic factor and cobalophilin in different parts of the gastrointestinal tract of the pig. AU - Marcoullis,G, AU - Merivuori,H, AU - Gräsbeck,R, PY - 1978/9/1/pubmed PY - 1978/9/1/medline PY - 1978/9/1/entrez SP - 705 EP - 12 JF - The Biochemical journal JO - Biochem J VL - 173 IS - 3 N2 - The vitamin B(12) binders in the pig pyloric mucosa gastric and intestinal juice from the upper gastrointestinal tract were fractionated into only two molecular forms, classified as intrinsic factor and cobalophilin. The unsaturated vitamin B(12)-binding power due to cobalophilin was lower in the intestinal than in the gastric juice. Electrofocusing revealed that intrinsic factor and cobalophilin in the intestinal juice contained more of the ;neutral'-type isoproteins, and the suggestion is made that this is due to enzyme activity. The gastric-juice intrinsic factor contained more acidic isoproteins, which supports the hypothesis that carbohydrate is added on to the polypeptide chain of this protein before it is secreted into gastric juice. The gastric- and intestinal-juice cobalophilins, studied also by electrofocusing, differed from that of pyloric mucosa and they appeared to be of salivary origin. With regard to molecular dimensions there was no significant difference between the intrinsic factors and cobalophilins from all sources studied. All cobalophilins had molecular weights by the formula of Svedberg of approx. 92500, Stokes radii of 4.62nm and sedimentation coefficients of 5.15S. The corresponding values for the intrinsic factors were 63600, 3.57nm and 4.38S. In addition, the intrinsic factors exhibited similar avidities for binding to the solubilized ileal intrinsic-factor receptor. Also the intrinsic factors and cobalophilins, irrespective of their source, bound to the analogous specific xenoantibodies with the same avidity. The present results demonstrate that intrinsic factor remains practically unaltered during its passage through the proximal intestine and render unlikely the speculations made about the presence of an endogenous binder for intrinsic factor as well as the existence of a ;pancreatic intrinsic factor'. In addition, they are compatible with the theory that the interference by undegraded cobalophilin may be the reason for the abnormal vitamin B(12) absorption observed in patients with pancreatic insufficiency. SN - 0264-6021 UR - https://www.unboundmedicine.com/medline/citation/708368/Comparative_studies_on_intrinsic_factor_and_cobalophilin_in_different_parts_of_the_gastrointestinal_tract_of_the_pig_ L2 - https://portlandpress.com/biochemj/article-lookup/doi/10.1042/bj1730705f DB - PRIME DP - Unbound Medicine ER -