Transcobalamin II assay method

Methods in Enzymology, 1997

2000

Background: Transcobalamin is essential for the cellu- lar internalization of cobalamin. Methods to quantify the unsaturated protein are available, but few attempts have been made to develop methods to quantify the sum of unsaturated and cobalamin saturated transcobal- amin. Methods: g-Globulins from two polyclonal rabbit anti- bodies against recombinant human transcobalamin were used as capture and detection antibodies, and recombinant

Clinical Chemistry, 2002

Background: Only cobalamin carried by transcobalamin (holo-transcobalamin) is available for cellular uptake and hence is physiologically relevant. However, no reliable or accurate methods for quantifying holo-transcobalamin are available. We report a novel holo-transcobalamin assay based on solid-phase capture of transcobalamin. Methods: A monoclonal antibody specific for human transcobalamin with an affinity constant >1010 L/mol was immobilized on magnetic microspheres to capture and concentrate transcobalamin. The cobalamin bound to transcobalamin was then released and assayed by a competitive binding radioassay. The quantification of holo-transcobalamin was accomplished using calibrators composed of recombinant, human holo-transcobalamin. Results: The assay was specific for holo-transcobalamin and had a detection limit of 5 pmol/L. Within-run and total imprecision (CV) was 5% and 8–9%, respectively. The working range (CV <20%) was 5–370 pmol/L. Dilutions of serum were linea...

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1983

Abstraet--l. Striking differences in physical and immunologic properties of transcobalamin II (TC II) in six mammalian species were noted.

FEBS Journal, 2005

Vitamin B 12 (cobalamin, Cbl) is absorbed in the distal ileum with the help of a specific binding protein intrinsic factor (IF) and appears in the circulation bound to another carrier transcobalamin (TC) . Tissue uptake of the TCAECbl complex (holo-TC) is mediated by specific receptors on the surface of the plasma membrane [2]. Holo-TC represents Cbl available for cellular uptake and a decrease in its level would indicate reduced absorption of the vitamin as well as systemic Cbl deficiency. Two new methods have recently been described for the measurement of holo-TC in plasma samples . Both methods employ TC-specific antibodies to capture the protein from plasma but lack the specificity needed for direct measurement of holo-TC in serum. The antigenic determinants and the functional domains of TC have not been identified.

Nutr Metab ( …, 2006

Background: Holotranscobalamin, cobalamin-saturated transcobalamin, is the minor fraction of circulating cobalamin (vitamin B12), which is available for cellular uptake and hence is physiologically relevant. Currently, no method allows simple, direct ...

2014

Museo, 2010

CATENA, 2024

AUTHORS Alfredo Mayoral, Ana Ejarque, Arnau Garcia-Molsosa, Mercourios Georgiadis, Giannis Apostolou, Vincent Gaertner, Constantina Kallintzi, Eurydice Kefalidou, Hèctor Orengo Highlights • We provide the first detailed Relative Mean Sea-Level curve for the Northern Aegean. • We detected for the first time in this coastal area the Neolithic drowned landscapes. • Palaeogeographic reconstruction shows coastal progradation due to anthropic forcing. • Historical events appear to dominate the fate of the city over environmental factors. • We detected the impact of a tsunami in 544 AD in this part of the Thracian coast.