Molybdenum
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This document discusses molybdenum, including its sources in foods like beans, nuts, and leafy greens. It is absorbed in the intestines and transported through the blood, storing primarily in the liver, kidneys, and bone. Molybdenum functions as a cofactor for enzymes involved in sulfur oxidation, purine catabolism, and other reactions. It is excreted mainly in the urine, and deficiencies have been associated with esophageal cancer while toxicity can cause gout-like symptoms at very high intakes.
Molybdenum
- 2. Sources Content depends on the concentration of Mo in the soil Found in larger amounts in black beans, walnuts and lentils Also in spinich, lettuce, whole wheat pasta and bread
- 4. Absorption, Transport and Storage Absorption increases as dietary intake of Mo increases. (22-1490 µg/day) Mo is transported in the blood as molybdate which is bound to albumin/ alpha-2 macroglobumin Mo is found in the tissues as molybdate, free molybdopterin or molybdopterin bound to enzymes
- 5. Mo can be found in high amounts and concentrations in the liver, kidneys and the bone. Also found in lower amounts and concentrations in the small intestine, lungs, spleen, brain, thyroid, adrenal glands and muscle
- 6. Functions and Mechanisms of Action Molybdopterin functions as a cofactor for the metalloenzymes (sulfite oxidase, aldehyde oxidase, xanthine deydrongenase and xanthine oxidase) It allows for Mo to bind to the catalytic site of the apo- enzyme Molybdopterin carries the Mo to the apoenzyme at its catalytic site where it undergoes further bonding
- 7. Dioxomolbdopterin is formed as the Mo is further bonded to 2 Oxygen molecules Oxosulfidomolybdopterin is formed as the Mo is further bonded to one Oxygen and one Sulphur
- 9. Sulfite Oxidase Located in the mitchondrial inner membrane Found in tissues of the heart, liver and kidney Contains iron sulphur clusters, 2 molybdopterins in the dioxo form and 2 cytochrome residues.
- 10. Catalyzes the terminal step in metabolism of methionine and cysteine. During this process sulfite is converted to sulfate The sulfite may be supplied through the diet because it is used as an antimicrobial agent during processing. The sulfate produced is excreted in the urine or is used for the synthesis of sulfolipids, sulfoproteins and mucopolysaccharides
- 12. Aldehyde Oxidase The enzyme uses the oxosulfido form of molybdpterin Functions in the liver whereby it uses O2 as it electron acceptor Substrates used in this reaction are compounds containing an aldehyde to generate carboxylic acids aldehyde + H2O + O2 <=> a carboxylate + H2O2 + H+
- 13. Xanthine Dehydrogenase(XD) and Xanthine Oxidase(XO) Both enzymes are iron dependant which require FAD and molybdopterin (oxosulfido form) XD is found in the tissues in the lungs, intestine, liver and kidneys XO is mainly in the intestines and thyroid cells
- 14. The enzymes are capable of hydroxylating purines, pyrimidines and other heterocyclic N containing Compounds Hypoxanthine generated from purine catabolism is oxidized to form xanthine and uric acid XD e- are transferred from the substrate to NAD+ to generate NADH + H+
- 15. XO O2 accepts (e-) from FADH2 and H2O2 Human disorder known as xanthinuria (Larger amts of xanthine are excreted in the urine) Higher concentrations of xanthine in the urine can cause the formation of kidney stones
- 16. Excretion Mo is excreted as molybdate mainly in the urine. It is excreted in smaller amounts in the feces (with the interaction Mo of bile), sweat (20µg) and the hair (0.01µg/g hair) Excretion increases as dietary Mo intake increases Hence little Mo is absorbed in the body
- 17. RDA for Mo Infants 0-0.5= 2µg ““““ 0.5-1=3µg Children 4-8= 22µg Male and Female 9-13= 34µg “ “ “ “ “ “ “ “ 14-18= 43µg “ “ “ “ “ “ “ “ 19- >70= 45µg Pregnant women = 50µg
- 18. Deficiency In China it has been documented with low Mo has been linked with esophageal cancer Congenital Mo cofactor deficiency disease in infants disrupts the body’s use of Mo in the metalloenzymes
- 19. Toxicity non toxic with intakes of 1500µg per Mo is relatively day. Possible to experience syntoms of gout (accumulation of uric acid in the joints resulting in inflammation) Occurs due to high concentrations of uric acid from XO and XD activity
- 22. References http://minerals.usgs.gov/minerals/pubs/commodity/ molybdenum/ http://www.lenntech.com/periodic/elements/mo.htm http://www.cancer.org/Treatment/TreatmentsandSide Effects/ComplementaryandAlternativeMedicine/Herb sVitaminsandMinerals/molybdenum