Isolation of Gastric Vitamin B12-binding Proteins Using Affinity Chromatography

Allen, Robert H.; Mehlman, Carol S.

doi:10.1016/s0021-9258(19)43979-3

Cited by 110 publications

(1 citation statement)

References 36 publications

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“…The migration corresponded to an estimated Mr of about 57,000. The A 2so1A360 ratio was higher than the ratio previously described by Allen et al (27). This could be explained by a partial desaturation of IF during the HPIEC step, as previously observed (19).…”

Section: 2supporting

confidence: 45%

Physicochemical Characterization and Biological Activity of Intrinsic Factor in Cystic Fibrosis

Monin,

Guéant,

Gérard

et al. 1990

J. pediatr. gastroenterol. nutr.

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Absorption of crystalline labeled cobalamin is strongly decreased in cases of cystic fibrosis. In order to determine if this is due to an alteration or a lack of activation of intrinsic factor by proteases, the physicochemical properties and biological activity of intrinsic factor have been studied. Intrinsic factor was purified 800‐fold from stimulated gastric juice of cystic fibrosis patients with a yield of 64.2%. Cystic fibrosis intrinsic factor had an estimated Mr of 57,000 in SDS‐polyacrylamide gel electrophoresis. Its carbohydrate content resembled that of normal human intrinsic factor, except that the ratio fucose/sialic acid was higher (6.1 and 1.6, respectively) and that the content in N‐acetylgalactosamine was decreased. The same alterations in carbohydrate composition were observed for He purified from cystic fibrosis saliva. Purified intrinsic factor from cystic fibrosis gastric juice was biologically active in vitro in the presence of ileal solubilized receptor as well as in vivo (Schilling test). The fate of iodinated cystic fibrosis intrinsic factor in guinea pig ileum studied by high‐resolution radioautography was similar to that of normal intrinsic factor. In conclusion, despite modifications of the carbohydrate content of the molecule, the biological activity of intrinsic factor is not altered in cases of cystic fibrosis. The malassimilation of crystalline cobalamin observed in cystic fibrosis is due to a mechanism independent from intrinsic factor secretion.

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Section: 2supporting

confidence: 45%