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Human plasma R-type vitamin B12-binding proteins. I. Isolation and characterization of transcobalamin I. TRANSCOBALAMIN III. and the normal granulocyte vitamin B12-binding protein.
J Biol Chem. 1975 Oct 10; 250(19):7700-6.JB

Abstract

Transcobalamin I and transcobalamin III have been purified approximately 6,000,000- and 3,000,000-fold, respectively, from normal human plasma using a purification scheme consisting of immunoadsorption, dialysis against 7.5 M guanidine HCl to remove endogenous vitamin B12, and affinity chromatography on vitamin B12-Sepharose. The two proteins were separated from each other subsequently by chromatography on DEAE-cellulose. The vitamin B12-binding protein present in granulocytes obtained from normal subjects has been purified approximately 5000-fold using affinity chromatography on vitamin B12-Sepharose as the sole purification technique. The final preparations of all three proteins were homogeneous based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Transcobalamin I and transcobalamin III belong to the R-typed class of vitamin B12-binding proteins and are indistinguishable from each other, and from the human granulocyte, milk, and saliva R-type vitamin B12-binding proteins, when studied by immunodiffusion with rabbit anti-human milk vitamin B12-binding protein sera. The carbohydrate compositions, expressed as moles of carbohydrate per mole of vitamin B12, of transcobalamin I, transcobalamin III, and the normal granulocyte vitamin B12-binding protein, respectively, are: sialic acid, 18, 11, 11; fucose, 9, 20, 24; galactose, 41, 51, 46; mannose, 24, 22, 20; galactosamine, 2, 2, 2; and glucosamine, 46, 54, 46. The high sialic acid content of transcobalamin I appears to account for the fact that this protein elutes after transcobalamin III and the normal granulocyte vitamin B12-binding protein during chromatography on DEAE-cellulose. This observation provides support for the hypothesis that differences among the R-type vitamin B12-binding proteins are due to differences in carbohydrate content. The similarities in carbohydrate composition and other properties of transcobalamin III and the granulocyte vitamin B12-binding protein provide support for the hypothesis that human plasma transcobalamin III is derived from granulocytes. The differences observed between transcobalamin I and the normal granulocyte vitamin B12-binding protein suggest that transcobalamin I may not be derived from granulocytes.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

1176444

Citation

Burger, R L., et al. "Human Plasma R-type Vitamin B12-binding Proteins. I. Isolation and Characterization of Transcobalamin I. TRANSCOBALAMIN III. and the Normal Granulocyte Vitamin B12-binding Protein." The Journal of Biological Chemistry, vol. 250, no. 19, 1975, pp. 7700-6.
Burger RL, Mehlman CS, Allen RH. Human plasma R-type vitamin B12-binding proteins. I. Isolation and characterization of transcobalamin I. TRANSCOBALAMIN III. and the normal granulocyte vitamin B12-binding protein. J Biol Chem. 1975;250(19):7700-6.
Burger, R. L., Mehlman, C. S., & Allen, R. H. (1975). Human plasma R-type vitamin B12-binding proteins. I. Isolation and characterization of transcobalamin I. TRANSCOBALAMIN III. and the normal granulocyte vitamin B12-binding protein. The Journal of Biological Chemistry, 250(19), 7700-6.
Burger RL, Mehlman CS, Allen RH. Human Plasma R-type Vitamin B12-binding Proteins. I. Isolation and Characterization of Transcobalamin I. TRANSCOBALAMIN III. and the Normal Granulocyte Vitamin B12-binding Protein. J Biol Chem. 1975 Oct 10;250(19):7700-6. PubMed PMID: 1176444.
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TY - JOUR T1 - Human plasma R-type vitamin B12-binding proteins. I. Isolation and characterization of transcobalamin I. TRANSCOBALAMIN III. and the normal granulocyte vitamin B12-binding protein. AU - Burger,R L, AU - Mehlman,C S, AU - Allen,R H, PY - 1975/10/10/pubmed PY - 1975/10/10/medline PY - 1975/10/10/entrez SP - 7700 EP - 6 JF - The Journal of biological chemistry JO - J Biol Chem VL - 250 IS - 19 N2 - Transcobalamin I and transcobalamin III have been purified approximately 6,000,000- and 3,000,000-fold, respectively, from normal human plasma using a purification scheme consisting of immunoadsorption, dialysis against 7.5 M guanidine HCl to remove endogenous vitamin B12, and affinity chromatography on vitamin B12-Sepharose. The two proteins were separated from each other subsequently by chromatography on DEAE-cellulose. The vitamin B12-binding protein present in granulocytes obtained from normal subjects has been purified approximately 5000-fold using affinity chromatography on vitamin B12-Sepharose as the sole purification technique. The final preparations of all three proteins were homogeneous based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Transcobalamin I and transcobalamin III belong to the R-typed class of vitamin B12-binding proteins and are indistinguishable from each other, and from the human granulocyte, milk, and saliva R-type vitamin B12-binding proteins, when studied by immunodiffusion with rabbit anti-human milk vitamin B12-binding protein sera. The carbohydrate compositions, expressed as moles of carbohydrate per mole of vitamin B12, of transcobalamin I, transcobalamin III, and the normal granulocyte vitamin B12-binding protein, respectively, are: sialic acid, 18, 11, 11; fucose, 9, 20, 24; galactose, 41, 51, 46; mannose, 24, 22, 20; galactosamine, 2, 2, 2; and glucosamine, 46, 54, 46. The high sialic acid content of transcobalamin I appears to account for the fact that this protein elutes after transcobalamin III and the normal granulocyte vitamin B12-binding protein during chromatography on DEAE-cellulose. This observation provides support for the hypothesis that differences among the R-type vitamin B12-binding proteins are due to differences in carbohydrate content. The similarities in carbohydrate composition and other properties of transcobalamin III and the granulocyte vitamin B12-binding protein provide support for the hypothesis that human plasma transcobalamin III is derived from granulocytes. The differences observed between transcobalamin I and the normal granulocyte vitamin B12-binding protein suggest that transcobalamin I may not be derived from granulocytes. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/1176444/Human_plasma_R_type_vitamin_B12_binding_proteins__I__Isolation_and_characterization_of_transcobalamin_I__TRANSCOBALAMIN_III__and_the_normal_granulocyte_vitamin_B12_binding_protein_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(19)40872-7 DB - PRIME DP - Unbound Medicine ER -