| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Technical Briefs |
1
Department of Clinical Biochemistry, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
2
The Laboratory for Protein Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark
aaddress correspondence to this author at: Department of Clinical Biochemistry, AKH, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark; fax 45-8949-3060, e-mail E.Nexo@dadlnet.dk)
We report a new method for measurement of holo-transcobalamin (holoTC), in which magnetic beads coated with vitamin B12 (cobalamins) precipitate apo-transcobalamin (apoTC) and the holoTC present in the supernatant is measured by ELISA.
Serum holoTC denotes the part of vitamin B12 accessible for the cells of the body and is considered to be a sensitive marker of vitamin B12 deficiency (1)(2)(3). Serum holoTC is not easily measured because it accounts for only approximately one-third of the circulating vitamin B12 and because the major part of TC circulates unsaturated with vitamin B12 (apoTC) (1)(2)(3). In the few published attempts to measure holoTC, TC is separated from the other vitamin B12-binding protein, haptocorrin, before quantification of vitamin B12. This allows a direct measurement of the cobalamins attached to TC (4)(5)(6) or an indirect calculation of holoTC from measurement of total plasma cobalamins and the plasma cobalamins not attached to TC (7)(8)(9). We have chosen another path.
We produced B12 beads and removed apoTC before ELISA quantification (10) of the protein moiety of holoTC. Vitamin B12 (400 mg; Fluka) was modified by acid treatment (11) to produce derivatives with a free COOH group. Magnetic beads (DB M-270 amine; DYNAL) from 10 mL of the original suspension were incubated overnight at room temperature with 10 mL of 2 mmol/L derivatives in 0.1 mol/L 2-morpholinoethane sulfonic acid, pH 5.5, in the presence of 10 mmol/L 1-ethyl-3-(dimethylaminopropyl)carbodiimide (Sigma). The beads were then washed twice with 50 mL of 1 mol/L Tris, pH 7.5, twice with 50 mL of 1 mol/L ammonium acetate, pH 4.6, and 10 times with 50 mL of 0.1 mol/L Tris–0.5 mol/L
References
The following articles in journals at HighWire Press have cited this article:
|
|
 |
|
  M. V. Bor, K. M von Castel-Roberts, G. P. Kauwell, S. P Stabler, R. H Allen, D. R Maneval, L. B Bailey, and E. Nexo Daily intake of 4 to 7 {micro}g dietary vitamin B-12 is associated with steady concentrations of vitamin B-12-related biomarkers in a healthy young population Am. J. Clinical Nutrition, March 1, 2010; 91(3): 571 - 577. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. F. Hardlei and E. Nexo A New Principle for Measurement of Cobalamin and Corrinoids, Used for Studies of Cobalamin Analogs on Serum Haptocorrin Clin. Chem., May 1, 2009; 55(5): 1002 - 1010. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. K. Lee, H.-S. Kim, and H. J. Kang Holotranscobalamin as an Indicator of Vitamin B12 Deficiency in Gastrectomized Patients Ann. Clin. Lab. Sci., January 1, 2009; 39(4): 361 - 366. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Vakur Bor, M. Cetin, S. Aytac, C. Altay, P. M. Ueland, and E. Nexo Long term biweekly 1 mg oral vitamin B12 ensures normal hematological parameters, but does not correct all other markers of vitamin B12 deficiency. A study in patients with inherited vitamin B12 deficiency Haematologica, November 1, 2008; 93(11): 1755 - 1758. [Full Text] [PDF]
|
|
|
|
 |
|
 A. Vogiatzoglou, H. Refsum, C. Johnston, S. M. Smith, K. M. Bradley, C. de Jager, M. M. Budge, and A. D. Smith Vitamin B12 status and rate of brain volume loss in community-dwelling elderly Neurology, September 9, 2008; 71(11): 826 - 832. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Brady, L. Wilson, L. McGregor, E. Valente, and L. Orning Active B12: A Rapid, Automated Assay for Holotranscobalamin on the Abbott AxSYM Analyzer Clin. Chem., March 1, 2008; 54(3): 567 - 573. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Morkbak*, A.-M. Hvas, N. Milman, and E. Nexo Holotranscobalamin remains unchanged during pregnancy. Longitudinal changes of cobalamins and their binding proteins during pregnancy and postpartum Haematologica, December 1, 2007; 92(12): 1711 - 1712. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Clarke, J. Birks, E. Nexo, P. M Ueland, J. Schneede, J. Scott, A. Molloy, and J. G. Evans Low vitamin B-12 status and risk of cognitive decline in older adults Am. J. Clinical Nutrition, November 1, 2007; 86(5): 1384 - 1391. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Clarke, P. Sherliker, H. Hin, E. Nexo, A. M. Hvas, J. Schneede, J. Birks, P. M. Ueland, K. Emmens, J. M. Scott, et al. Detection of Vitamin B12 Deficiency in Older People by Measuring Vitamin B12 or the Active Fraction of Vitamin B12, Holotranscobalamin Clin. Chem., May 1, 2007; 53(5): 963 - 970. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. M von Castel-Roberts, A. L. Morkbak, E. Nexo, C. A Edgemon, D. R Maneval, J. J Shuster, J. F Valentine, G. P. Kauwell, and L. B Bailey Holo-transcobalamin is an indicator of vitamin B-12 absorption in healthy adults with adequate vitamin B-12 status Am. J. Clinical Nutrition, April 1, 2007; 85(4): 1057 - 1061. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Morkbak, A.-M. Hvas, Z. Lloyd-Wright, T. A.B. Sanders, O. Bleie, H. Refsum, O. K. Nygaard, and E. Nexo Effect of Vitamin B12 Treatment on Haptocorrin Clin. Chem., June 1, 2006; 52(6): 1104 - 1111. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Obeid, A. L. Morkbak, W. Munz, E. Nexo, and W. Herrmann The Cobalamin-Binding Proteins Transcobalamin and Haptocorrin in Maternal and Cord Blood Sera at Birth Clin. Chem., February 1, 2006; 52(2): 263 - 269. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. V. Bor, E. Lydeking-Olsen, J. Moller, and E. Nexo A daily intake of approximately 6 {micro}g vitamin B-12 appears to saturate all the vitamin B-12-related variables in Danish postmenopausal women Am. J. Clinical Nutrition, January 1, 2006; 83(1): 52 - 58. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Refsum, C. Johnston, A. B. Guttormsen, and E. Nexo Holotranscobalamin and Total Transcobalamin in Human Plasma: Determination, Determinants, and Reference Values in Healthy Adults Clin. Chem., January 1, 2006; 52(1): 129 - 137. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. V. Bor, M. Cetin, S. Aytac, C. Altay, and E. Nexo Nonradioactive Vitamin B12 Absorption Test Evaluated in Controls and in Patients with Inherited Malabsorption of Vitamin B12 Clin. Chem., November 1, 2005; 51(11): 2151 - 2155. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. Chen, A. F Remacha, M P. Sarda, and R. Carmel Influence of cobalamin deficiency compared with that of cobalamin absorption on serum holo-transcobalamin II Am. J. Clinical Nutrition, January 1, 2005; 81(1): 110 - 114. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. V. Bor, E. Nexo, and A.-M. Hvas Holo-Transcobalamin Concentration and Transcobalamin Saturation Reflect Recent Vitamin B12 Absorption Better than Does Serum Vitamin B12 Clin. Chem., June 1, 2004; 50(6): 1043 - 1049. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Refsum, A. D. Smith, P. M. Ueland, E. Nexo, R. Clarke, J. McPartlin, C. Johnston, F. Engbaek, J. Schneede, C. McPartlin, et al. Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion Clin. Chem., January 1, 2004; 50(1): 3 - 32. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. Lloyd-Wright, A.-M. Hvas, J. Moller, T. A.B. Sanders, and E. Nexo Holotranscobalamin as an Indicator of Dietary Vitamin B12 Deficiency Clin. Chem., December 1, 2003; 49(12): 2076 - 2078. [Full Text] [PDF]
|
|
|
|
|
|
A. McCaddon, P. Hudson, C. McCracken, R. Ellis, and A. McCaddon Biological Variation of Holo-Transcobalamin in Elderly Individuals Clin. Chem., September 1, 2003; 49(9): 1542 - 1544. [Full Text] [PDF]
|
|
|
|
|
|
H. Zetterberg, E. Nexo, B. Regland, L. Minthon, R. Boson, M. Palmer, L. Rymo, and K. Blennow The Transcobalamin (TC) Codon 259 Genetic Polymorphism Influences Holo-TC Concentration in Cerebrospinal Fluid from Patients with Alzheimer Disease Clin. Chem., July 1, 2003; 49(7): 1195 - 1198. [Full Text] [PDF]
|
|
|
|
|
|
S. Loikas, M. Lopponen, P. Suominen, J. Moller, K. Irjala, R. Isoaho, S.-L. Kivela, P. Koskinen, and T.-T. Pelliniemi RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval Clin. Chem., March 1, 2003; 49(3): 455 - 462. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Obeid, M. Jouma, and W. Herrmann Cobalamin Status (Holo-Transcobalamin, Methylmalonic Acid) and Folate as Determinants of Homocysteine Concentration Clin. Chem., November 1, 2002; 48(11): 2064 - 2065. [Full Text] [PDF]
|
|
|
|
|
|
E. Nexo, A.-M. Hvas, O. Bleie, H. Refsum, S. N. Fedosov, S. E. Vollset, J. Schneede, J. E. Nordrehaug, P. M. Ueland, and O. K. Nygard Holo-Transcobalamin Is an Early Marker of Changes in Cobalamin Homeostasis. A Randomized Placebo-controlled Study Clin. Chem., October 1, 2002; 48(10): 1768 - 1771. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Carmel Measuring and Interpreting Holo-Transcobalamin (Holo-Transcobalamin II) Clin. Chem., March 1, 2002; 48(3): 407 - 409. [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
