TRACE ELEMENTS Hossein Piri Department of Biochemistry and

TRACE ELEMENTS Hossein Piri Department of Biochemistry and Genetics, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran September 2012

1. Major components of body molecules C, H, O, N, S (obtained through intake of water fat, carbohydrates, proteins) 2. Nutritionally important minerals Ca, P, Mg, Na K, Cl (<100 mg/day) 3. Trace elements Cr, Co, Cu, I, F, Fe, Mn, Mo, Se, Zn 4. Additional elements (non-essential for humans) Ni, Sn, V, B, Li

Transport and storage require specific binding to carrier proteins Transferrin – Fe, Cr, Mn, Zn Albumin – Cu, Zn Amino acids – Cu, (Fe) Trancobaltamin - Co Globulins - Mn

Normal routes of excretion of trace elements Bile – Cu, Mn, Cr, Zn, Urine – Co, Cr, Mo, Zn Pancreatic juice – Zn Sweat – Zn Mucosal cell sloughing – Fe, Zn

Chromium • Regulation of glucose metabolism as a component of glucose tolerance factor (GTF). • GTF increases effect of insulin (by facilitating its binding to cell receptor site). • Chromium regulates plasma lipoprotein concentration. • Reduces serum cholesterol and serum triglycerides.

Food iron is predominantly in the ferric state. In the stomach, where the p. H is less than 4, Fe 3+ can dissociate and react with low-molecular weight compounds such fructose, ascorbic acid, citric acid, amino acids to form ferric complexes soluble in neutral p. H of intestine fluid. A protein DMT 1 (divalent metal transporter 1), which transports all kinds of divalent metals, then transports the iron across the cell membrane of intestinal cells. These intestinal lining cells can then store the iron as ferritin. The transfer of iron from the storage ferritin (as Fe 3+ ) involves reduction to ferrous state – Fe 2+ in order for it to be released from ferritine. The Fe 2+ is subsequently again oxidized by ferroxidase ceruloplasmin and transported bound to plasma transferrin to storage sites in the bone marrow, liver muscle, other tissues.

Manganese • • High concentration of Mn 2+ is present in mitochondria Functions as a necessary factor for activation of glycosyltransferases (enzymes responsible for the synthesis of oligosaccharides, glycoproteins, proteoglycans. Required for superoxid dismutase activity, for activity of metalloenzymes: hydrolases kinases decarboxylases transferases. Deficiency of Mn extensively reduce glycoprotein and proteoglycan formation.

Selenium • • • an integral component of glutathion peroxidase (intracellular antioxidant), a scavenger of peroxides, an essential element for immune function (selenoproteins). • Selenoproteins catalyse oxido-reduction reactions, protective function from oxidative stress (macrophage- or neutrophil-generated free-radical species, UV in sunlight. • The foot content of Se is highly dependent upon the soil type in which the foodstuff are grown.

ﺭﻭی • • • carbonic anhydrase lactate dehydrogenase glutamate dehydrogenase alkaline phosphatase thimidine kinase matrix metalloproteinases • Gustin – protein in saliva – major role in taste.