Characterization of the cobalamins
attached to transcobalamin I and transcobalamin II in human plasma.
Spectroscopic studies of nitric oxide (NO) interactions with cobalamins
: reaction of NO with superoxocobalamin(III) likely accounts for cobalamin
reversal of the biological effects of NO.
ARS scientists are testing various food and supplement samples using CE-ICP-MS to measure the various cobalamins
Conversely, approximately 75% of plasma cobalamin
binds to TCI, (2) a nonspecific R-binder protein similar to gastric R-binder protein ("R" denotes rapid electrophoretic mobility, distinguishable from intrinsic factor).
The cobalt in hydroxocobalamin is in the 3+ state and cobalamin
is abbreviated [Cbl.
Based on analyses in cobalamin
-deficient patients before and after therapy, Morkbak and colleagues (1) confirm our finding that cobalamin
concentrations correlate with haptocorrin (HC; transcobalamin I) (2) but propose that HC concentrations are regulated by cobalamin
status rather than being genetically deter mined, which they mistake as my view.
HC is synthesized in many cells of the body, including leukocytes, and it binds between 80% and 94% of total Cobalamin
in plasma (6).
In the commercial assay, the magnetic beads for capturing TC are the same, but cobalamins
are determined by RIA.
ROC curves and areas [with 95% confidence intervals (CIs)] were used to estimate diagnostic accuracy for an increase in holo-TC and cobalamin
as a diagnostic marker for diagnosing vitamin Blz malabsorption.
in the supernatants from the beads were analyzed by a commercial protein-binding assay (Bayer a/s) on Centaur equipment (reference interval, 200-600 pmol/L).
and erythrocyte folate were determined on the ACS:Centaur [TM] Automated Chemiluminescence System (Bayer A/S) by a competitive protein-binding assay (CV <10%).
The central role of transcobalamin in the metabolism of cobalamin
has challenged researchers since its discovery in the 1960s (3).