Identification of the Vitamin B12-Binding Protein in the Serum of Normals and of Patients with Chronic Myelocytic Leukemia

Mendelsohn, Robert S.; Watkin, Donald M.; Horbett, Ann P.; Fahey, John L.

doi:10.1182/blood.v13.8.740.740

Cited by 62 publications

(13 citation statements)

References 6 publications

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“…A partial list of the possible contaminants includes FSH,I5 transcortin,16 thyroxine," and vitamin B12. 18 In addition, we have noted that Armour lot number K103-124 erythropoietin, but not human urinary ESF, h a s the capacity to expand amphibian m e l a n o p h~r e s~~ whereas Armour lot number D-216-155CAB beta-MSH was found not to be erythropoietic in t h e a s s a y described by White e t al. 12 We hope that the newer techniques of gel and immunoelectrophoresis as well a s further studies employing biological a s s a y s for a wider varietyof trace contaminants will help i n the resolution of a single ESF component from t h i s truly microheterogeneous alpha globulin material.…”

Section: Purification Of Human Urinary Esfmentioning

confidence: 69%

Purification and Physiological Effects of Human Urinary Erythropoietin*

1961

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Section: Purification Of Human Urinary Esfmentioning

confidence: 69%

Purification and Physiological Effects of Human Urinary Erythropoietin*

1961

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“…Recent administration of B12, either orally or parenterally, or in vitro addition to serum or plasma results in the greater part of the B12 being bound to a second binding protein, transcobalamin I1 (TC 11) of Hall & Finkler (1964) or the beta globulin B12 binder of Retief et al (1967). The endogenous B12 of normal human serum is all bound to TC I, none being detected bound to TC I1 by available fractionation methods (Mendelsohn et al 1958, Gabuzda et al 1965).…”

mentioning

confidence: 99%

The Vitamin B₁₂ Binding Capacity of Transcobalamin I and II of Normal Human Serum

Hom

Ahluwalia

1968

Scandinavian Journal of Haematology

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The unsaturated serum vitamin B,, binding capacity (UB,,BC) of transcobalamin 0, I and I1 (TC 0, I and 11) of 50 normal subjects was determined by gel filtration on Sephadex G-200. TC 0 bound from 0 to 76 pg. per ml. of serum, accounting for up to 5.2 per cent of the UB,,BC, while TC I bound from 72 to 1057 pg. per ml., or up to 47.1 per cent of the UB,,BC. TC I1 bound from 650 to 1891 pg. per ml., accounting for up to 90.3 per cent of the UB,,BC.There was a significant positive correlation between the binding capacity of TC I and of TC I1 when each was compared with the total unsaturated B,, binding capacity. A positive correlation therefore existed between the binding capacity of TC I and that of TC 11. TC 0, I and I1 were the only binders of added B,, over a range from 75 to 20,760 pg. per ml. of serum. The relative amount of B,, bound to TC I and to TC I1 remained fairly constant in an individual serum regardless of the amount of B,, added.Abridgement of a thesis submitted by B.K.A. in fulfillment of the Fellowship of the

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“…Until recently the nature of the B, binding system has been confused. A number ofinvestigations have been published including those of Miller and Sullivan (1959a), Weinstein et al (1959) and Mendelsohn, Watkin, Horbett and Fahey (1958). In suniinary thcsc show that the /.…”

Section: Discussionmentioning

confidence: 99%

The Nature of the Vitamin B₁₂ Binding Protein in Human Serum*

Hardwicke

1966

Br J Haematol

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IT HAS been known for some years that the vitamin B12 circulating in the plasma is bound to protein. When this plasma binding capacity is exceeded, by the oral or intravenous administration of large doses of the vitamin, the excess unbound vitamin is rapidly excreted in the urine (Mollin and ROSS, 1953). The exact nature ofthis binding protein has yet to be identified. hi normal subjects and in patients with myeloproliferative disorders it migrates electrophoretically with the speed of an a,-globulin, and is present in that fraction of the serum proteins which is not precipitated by 0.6 M-perchloric acid, the seromucoid fraction (Weinstein, Weissniaii and Watkin, 1959). This serum fraction contains a number of antigenically distinct proteins (Burtin, 1964)~ two of which have been identified respectively as Orosomucoid and the a,-acid-glycoprotein of Schultze (Hardwicke and St. Cyr, 1961).In this paper the binding of vitamin B,, to the constituent fractions of a seromucoid, obtaincd by (NH4)z SO4 fractionation of serum, has been investigated by chromatography on DEAE-cellulose. Binding into this seromucoid fraction of the serum proteins is confirmed, in iiorinals and in myeloproliferative disorders, but this binding appears to be onto two separable serum proteins which are neither the Orosoniucoid nor any other recognized a1glycoprotein. METHODSScrurn was separated from venous blood samples and stored at -zoo C. until used.Vitaniin B, , was estimated by micro-biological assay with Euglenagracilir Z strain. Radioactive Biz. Cyanocobalamin 5 8 Co (specific activity > I pC./mg.) and Cyanocobalaiiiin 7 c~ (specific activity> 10 pC./nig.) were obtained from the Radiochemical Centre, Amersham, England. Estimations of radioactivity were made on a well-type sodium iodide scintillation counter.St.romucoid fractions were prepared by the addition to whole serum of an equal volunie of saturated ammonium sulphate. A first precipitate ('A') was harvested. The pH was then reduced slowly to 3.8 by the addition of 2 N-HC~, and a further precipitate ('B') was formed. The first of these contains mainly globulin fractions and the second mainly albumin (Winzler, Devor, Mehl and Smyth, 1948). The supernatant is analogous to the seroinucoid fraction of serum. This method of preparation is preferred since the addition of strong acid to reduce the pH to 1-2, as is found in the perchloric method, will remove a substantial proportion of the a-acetyl-neuraminic acid from the glycoproteins, with consequent alterations in the physical characteris tics (Hardwicke, personal observation).Additioii ofB,, to seritnz, OY tojactions. When radioactive vitamin was added to a protein

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Identification of the Vitamin B12-Binding Protein in the Serum of Normals and of Patients with Chronic Myelocytic Leukemia

Cited by 62 publications

References 6 publications

Purification and Physiological Effects of Human Urinary Erythropoietin*

Purification and Physiological Effects of Human Urinary Erythropoietin*

The Vitamin B₁₂ Binding Capacity of Transcobalamin I and II of Normal Human Serum

The Nature of the Vitamin B₁₂ Binding Protein in Human Serum*

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Identification of the Vitamin B12-Binding Protein in the Serum of Normals and of Patients with Chronic Myelocytic Leukemia

Cited by 62 publications

References 6 publications

Purification and Physiological Effects of Human Urinary Erythropoietin*

Purification and Physiological Effects of Human Urinary Erythropoietin*

The Vitamin B12 Binding Capacity of Transcobalamin I and II of Normal Human Serum

The Nature of the Vitamin B12 Binding Protein in Human Serum*

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Product

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The Vitamin B₁₂ Binding Capacity of Transcobalamin I and II of Normal Human Serum

The Nature of the Vitamin B₁₂ Binding Protein in Human Serum*