Search results
Results from the WOW.Com Content Network
Iron toxicity results when the amount of circulating iron exceeds the amount of transferrin available to bind it, but the body is able to vigorously regulate its iron uptake. Thus, iron toxicity from ingestion is usually the result of extraordinary circumstances like iron tablet over-consumption [1] [ 42 ] rather than variations in diet .
The coordination sphere of the calcium ion contains only carboxylate oxygen atoms and no nitrogen atoms. This is consistent with the hard nature of the calcium ion. The protein has two approximately symmetrical domains, separated by a flexible "hinge" region. Binding of calcium causes a conformational change to occur in the protein.
Calcium-binding proteins can be either intracellular and extracellular. Those that are intracellular can contain or lack a structural EF-hand domain. Extracellular calcium-binding proteins are classified into six groups. [2] Since Ca (2+) is an important second messenger, it can act as an activator or inhibitor in gene transcription.
Ferroportin-mediated iron efflux is calcium-activated; studies of human Fpn expressed in Xenopus laevis oocytes demonstrated that calcium is a required cofactor for Fpn, but that Fpn does not transport calcium. [12] Thus, Fpn does not function as an iron/calcium antiporter. The thermodynamic driving force for Fpn remains unknown.
Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula [CH 2 N(CH 2 CO 2 H) 2] 2.This white, slightly water-soluble solid is widely used to bind to iron (Fe 2+ /Fe 3+) and calcium ions (Ca 2+), forming water-soluble complexes even at neutral pH.
Iron-binding proteins are carrier proteins and metalloproteins that are important in iron metabolism [1] and the immune response. [2] [3] Iron is required for life.Iron-dependent enzymes catalyze a variety of biochemical reactions and can be divided into three broad classes depending on the structure of their active site: non-heme mono-iron, non-heme diiron , or heme centers. [4]
A calprotectin dimer can bind only one manganese or iron ion with high affinity, and it can do this only in the presence of calcium. [9] [19] [6] Zinc can bind at two sites within the calprotectin dimer, and this can occur in the absence of calcium. [2] Calcium, however, improves calprotectin's affinity for zinc. [9]
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]