Radioiodination of human intrinsic factor

Mackenzie, Iain; Donaldson, Robert M.; Schilling, Robert F.

doi:10.1172/jci106009

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…After 'Co radioactivity had been removed from microvillous membranes, the supernate containing removed radioactivity was concentrated by ultrafiltration through VisKing casing (16). The characteristics of this radioactivity were compared with those of hamster IFB,2 which had not been previously incubated with microvillous membranes.…”

Section: Methodsmentioning

confidence: 99%

“…To obtain sufficient radioactivity for adequate examination, it was necessary to pool supernates from replicate experiments. Sephadex G-200 gel filtration was performed in 0.05 M phosphate buffer pH 7.5 using a reverse flow 2.5 X 100 cm column (16). Vertical electrophoresis on starch gel was carried out for 20 hr at 40C and 130 v in borate buffer, pH 8.6 (17).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of divalent cations and pH on intrinsic factor-mediated attachment of vitamin B12 to intestinal microvillous membranes

Mackenzie¹,

Donaldson²

1972

J. Clin. Invest.

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A B S T R A C T Calcium, but not other divalent cations, is required for optimal-uptake of intrinsic factor-bound 57Co-labeled cyanocobalamin (IFB12) by microvillous membranes isolated from hamster ileal-absorptive cells. Chelation of divalent cations by disodium ethylenediaminetetraacetate (EDTA) promptly removes IFB12 previously attached to microvillous membranes. High concentrations of CaC12 or MgCl2 also markedly inhibit membrane uptake of IFBl2 and rapidly remove previously attached IFB12. Similarly, reduction of pH to below 5.4 prevents membrane attachment of IFB,2 and removes virtually all IFB,2 already bound to microvillous membranes. The effects of calcium depletion, increased salt concentrations, and acidification on membrane uptake of IFB, were completely reversible. These findings are consistent with the concept that the formation of calcium salt bridges is essential for attachment of IFB,2 to the ileal-absorptive surface.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of divalent cations and pH on intrinsic factor-mediated attachment of vitamin B12 to intestinal microvillous membranes

Mackenzie¹,

Donaldson²

1972

J. Clin. Invest.

Self Cite

View full text Add to dashboard Cite

show abstract

“…At least, the data did not support the possibility of absorption of IFBl2, yet it did not exclude the possibility of absorption of unlabeled or weakly labeled fragments of the IF, as the authors put it. More sophisticated label ing has recently been carried out by Mackenzie et al [53], who first purified human IF saturated with 60CoBI2, and then labeled IF-0uCoBi2 with 125I. These proceduresdid not markedly alterthe chromatographic, electrophoretic, antigenic and biologic properties of the IF.…”

Section: Fate O F If-b12 Complexmentioning

confidence: 99%