From Wikipedia, the free encyclopedia
Metal metabolism refers to the metabolic role of certain metals, such as iron and zinc.
Inorganic elements play critical roles in metabolism; some are abundant (e.g. sodium and potassium) while others function at minute concentrations. About 99% of mammals' mass are the elements carbon, nitrogen, calcium, sodium, chlorine, potassium, hydrogen, phosphorus, oxygen and sulfur.[1] The organic compounds (proteins, lipids and carbohydrates) contain the majority of the carbon and nitrogen and most of the oxygen and hydrogen is present as water.[1]
Electrolytes
The abundant inorganic elements act as ionic electrolytes. The most important ions are sodium, potassium, calcium, magnesium, chloride, phosphate, and the organic ion bicarbonate. The maintenance of precise gradients across cell membranes maintains osmotic pressure and pH.[2] Ions are also critical for nerves and muscles, as action potentials in these tissues are produced by the exchange of electrolytes between the extracellular fluid and the cytosol.[3] Electrolytes enter and leave cells through proteins in the cell membrane called ion channels. For example, muscle contraction depends upon the movement of calcium, sodium and potassium through ion channels in the cell membrane and T-tubules.[4]
Transition metals
The transition metals are usually present as trace elements in organisms, with zinc and iron being most abundant.[5][6] These metals are used in some proteins as cofactors and are essential for the activity of enzymes such as catalase and oxygen-carrier proteins such as hemoglobin.[7] These cofactors are bound tightly to a specific protein; although enzyme cofactors can be modified during catalysis, cofactors always return to their original state after catalysis has taken place. The metal micronutrients are taken up into organisms by specific transporters and bound to storage proteins such as ferritin or metallothionein when not being used.[8][9]
See also
References
- ^ a b Heymsfield S, Waki M, Kehayias J, Lichtman S, Dilmanian F, Kamen Y, Wang J, Pierson R (1991). [Expression error: Missing operand for > "Chemical and elemental analysis of humans in vivo using improved body composition models"]. Am J Physiol 261 (2 Pt 1): E190–8. PMID 1872381.
- ^ Sychrová H (2004). "Yeast as a model organism to study transport and homeostasis of alkali metal cations" (PDF). Physiol Res 53 Suppl 1: S91–8. PMID 15119939. http://www.biomed.cas.cz/physiolres/pdf/53%20Suppl%201/53_S91.pdf.
- ^ Levitan I (1988). [Expression error: Missing operand for > "Modulation of ion channels in neurons and other cells"]. Annu Rev Neurosci 11: 119–36. doi:10.1146/annurev.ne.11.030188.001003. PMID 2452594.
- ^ Dulhunty A (2006). [Expression error: Missing operand for > "Excitation-contraction coupling from the 1950s into the new millennium"]. Clin Exp Pharmacol Physiol 33 (9): 763–72. doi:10.1111/j.1440-1681.2006.04441.x. PMID 16922804.
- ^ Mahan D, Shields R (1998). "Macro- and micromineral composition of pigs from birth to 145 kilograms of body weight". J Anim Sci 76 (2): 506–12. PMID 9498359. http://jas.fass.org/cgi/reprint/76/2/506.
- ^ Husted S, Mikkelsen B, Jensen J, Nielsen N (2004). [Expression error: Missing operand for > "Elemental fingerprint analysis of barley (Hordeum vulgare) using inductively coupled plasma mass spectrometry, isotope-ratio mass spectrometry, and multivariate statistics"]. Anal Bioanal Chem 378 (1): 171–82. doi:10.1007/s00216-003-2219-0. PMID 14551660.
- ^ Finney L, O'Halloran T (2003). [Expression error: Missing operand for > "Transition metal speciation in the cell: insights from the chemistry of metal ion receptors"]. Science 300 (5621): 931–6. doi:10.1126/science.1085049. PMID 12738850.
- ^ Cousins R, Liuzzi J, Lichten L (2006). "Mammalian zinc transport, trafficking, and signals". J Biol Chem 281 (34): 24085–9. doi:10.1074/jbc.R600011200. PMID 16793761. http://www.jbc.org/cgi/content/full/281/34/24085.
- ^ Dunn L, Rahmanto Y, Richardson D (2007). [Expression error: Missing operand for > "Iron uptake and metabolism in the new millennium"]. Trends Cell Biol 17 (2): 93–100. doi:10.1016/j.tcb.2006.12.003. PMID 17194590.
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