2. INTRODUCTION
What is minerals metabolism?
Chemical processes undergo by minerals that occur
within a living organism in order to maintain life
IODINE
Sources:
Sea water, fish, cereals, vegetables and iodize
salt
ZINC
Sources: legumes, potato, cabbage
3. IODINE
Biochemical function:
Formation of thyroid hormones
Thyroxine (T4)
Tri-iodothyronine (T3)
Total body contains: 25-30 mg of iodine
Normal level in blood: 5-10 mg/dL
80 % stored in the thyroid gland
Daily requirement: 150-200 µg/day
4. IODINE METABOLISM
GOITROGENS
- Ingredients in foodstuffs, which prevent
utilization of iodine
- Cassava, maize, millet, bamboo shoots,
sweet potatoes and beans
THIOCYANATE
- Inhibits iodine uptake by thyroid
- Cabbage and tapioca
6. Step 1: Uptake of Iodine
Step 2: Oxidation of Iodine
Step 3: Iodination
Step 4: Coupling
Step 5: Storage
Step 6: Utilization
Step 7: Hydrolysis
Step 8: Release
Step 9: Salvaging of iodine
Step 10:Transport of thyroid hormones
Step 11:Catabolism of thyroid hormones
7. Step 1: Uptake of iodine
-thyroid gland takes up
and concentrates iodine
Inhibition:
thiocyanate & perchlorate
Stimulate:TSH
Congenital defectiodine
trapping,maybe treated
by large doses of iodine
8. Step 2: Oxidation of iodine
-oxidized to active form
(I- I+) *can only be performed in a
thyroid
-catalyzed by thyroperoxidase
-NADPH-dependent reaction
Inhibition:
Antithyroid drugs; thiourea, thiouracil
and methimazole
Stimulate:TSH
Congenital defectiodide oxidation
defect, treatment withT4 is
administered
9. Step 3: Iodination
-Thyroglobulin (Tgb) is
iodinated
-Tgb secreted by the
thyroid follicular cells
-So 3,5-di-iodotyrosin
(DIT) and 3-
monoiodotyrosine (MIT)
are produced
10. Step 4: Coupling
Location: in the border of the follicular cells
Some of the tyrosine residues in the thyroglobulin are aligned opposite to
each other and are coupled.
When two DIT molecules couple, one molecule of tetraiodothyronine (T4) is
formed.
Tri-iodo-tyronine (T3) may be formed by de-ionization of outer ring ofT4 by
5’-deiodinase.
Under normal condition,99% is produced byT4.
Iodotyrosyl coupling defect will be treated by giving T4
13. ZINC
As a cofactor:-
Carboxypeptidase A
DNA polymerase & RNA polymerase
Superoxide dismutase
Carbonic anhydrase
Total zinc content of body: 2g (60% in skeletal
muscle, 30 % in bones)
Daily intake for adults and children: 10 mg/day
Daily intake for lactation and pregnancy: 15-20
mg/day
14. Highest concentration of zinc: hippocampus
area of brain and prostatic secretion
Rich dietary sources:
beans,nuts,cheese,meat and shellfish
Copper,calcium,cadmiun,iron and phytate
will interfere with absorption of zinc.
Zinc can be used to reduce copper absorption
inWilson’s disease
15. In liver, zinc is stored in combination with a
specific protein, metallothionein.
Zinc is excreted through pancreatic juice and to a
lesser extent through sweat.
Zinc stabilize insulin molecules in pancreas
Zinc containing protein (Gusten) in saliva is for
taste sensation
17. Zinc toxicity
intake > 1000 mg/day
Inhalation of zinc oxide fumes
Rat poisons
Chronic toxicity can lead to gastric ulcer,
pancreatitis, anemia, nausea, vomiting and
pulmonary fibrosis.
Acute toxicity is manifested as fever, excessive
salivation, headache and anemia
18. DEFICIENCY of ZINC
Poor growth
Hypogonadism
Impaired wound healing
Reduction in number ofT and B lymphocytes
Depression, dementia and other psychiatric
disorders
Impotence in male
19. REFERENCES
Vasudevan, D., S, S., &Vaidyanathan, K.
(2013).Textbook of biochemistry for medical
students.New Delhi: Jaypee Brothers Medical
Publishers (P) Ltd.