8 Non-enzymatic Vitamin B12 Binding Proteins in Man and Animals

Schneider, Zenon

doi:10.1515/9783110844795.267

Cited by 3 publications

(1 citation statement)

References 150 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Milk, meat and, in particular, liver are the principal sources of this vitamin for humans. Because of its very low concentration at which it is available in food, the uptake from the digestive system in humans and the transport into the cells is one of the most effective and elaborated processes developed by nature (Linde mans and Kapel, 1979;Schneider, 1987a). The route of cobalt from soil to human cells is long and may proceed in the following main steps: (Bd -> human gut )-> cells (B I2 ) The uptake is characterized by extremely strong and specifie binding of the vitamin by B 12 carriers at ail steps.…”

Section: Introductionmentioning

confidence: 99%

Cobalt binding by Propionibacterium arabinosum

Schneider¹,

Trojanowska

Jaszewski

et al. 1995

Lait

Self Cite

View full text Add to dashboard Cite

Summary -Cobalt occurs in nature usually at very low concentrations and is accompanied by much higher concentrations of various metals. In order to acquire cobalt under such unfavorable conditions, living systems evolved effective uptake mechanisms based on high affinity to cobalt and distinguishing this element from among the others. Taking Propionibacterium arabinosum as the bacterial rnodel, which is known for its cobalt requirement, the performance of microorganisms has been examined in this regard. By using radiolabeled cobalt and a filter technique, the uptake capability of these bacteria at the stage of cobalt binding has been characterized in terms of binding capacity, and dissociation and equilibrium constants. Monovalent and divalent ions inhibit cobalt binding to bacteria. Divalent metal ions showed a competitive mode of inhibition, and the inhibitory constants for some of the toxic and biologically important divalent metal ions were determined. The chelating agent EDT A diminishes cobalt binding to bacteria already at concentration 10-5 Ilmoi/i. Bacteria

show abstract

Section: Introductionmentioning

confidence: 99%