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