Essential and trace ionsEssential and trace ions
Ions with biochemical functions and have deficiency syndrume are :
Iron and Iodide
Ions studied are :
iodide, copper,zinc,sulfur,chromium ,ma
nganese,selenium, etc. ,iron1
Iron functions in respiratory chain are:
i – an electron carrier ii- transport of molecular
oxygen
Iron
Most iron is associated with protiens
-: First : Hemoproteins
responsible for respiration Two group proteinsand for transport oxygen .
2
((aa ) )Cytochrome – cCytochrome – c: :
An respiratory Enzyme, where iron is complexedcovalently with the protein portion in a porphyrin
ring ) heme ring ( .
Iron act as electron carrier by changing from
ferrousto the ferric form and reversibly .
Cytochrome –c role is in oxidation – reduction
process of iron .
3
( (bb ) ) Hemoglobin and Hemoglobin and myoglobinmyoglobin
Hemoproteins which store and/or transport Oxygen
-Myoglobin:
. A single polypeptide with one oxygen binding site
An oxygen carrying protein.
Binds and releases oxygen through changes in
oxygen conc. in sarcoplasma of skeletal muscle cells. 4
HemoglobinHemoglobinFound in high conc. in red blood
cells.It binds to oxygen in lungs and transports
it to body cells, also transports CO2 from tissues to lungs .
Hemoglobin has 4 protein chains ,each one has a heme ) porphyrin ring ( and ferrous
iron .
Iron complexes O2 by using its vacant pair of non bonding electrons .
5
Uptake and release of O2 is influensed by -:
1 -The oxygen tension. 2 -PH
3 -Presence of 2,3 diphosphoglycerate . 4 -CO2 concenteration.
Patients with iron-deficiency animia have- :
a- Decreased capability for oxygen transport.
b- Decreased in hemoglobin synthesis.
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Iron storage and transport Iron storage and transport proteinsproteinsBody handeling of iron requirments is by
storage and transport proteins
a – The iron storage proteins Found in liver, bone marrow and
spleen.Ferritin :
- A water soluble iron protein built up from apoferrtin and micelles of ferric
hydroxide-phosphate complex . Iron is stored in ferritin as Fe3+ form and
released as Fe2 +
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HemosiderinHemosiderin
A water insoluble protein considered as
a dehydrated form of ferritin .
b – Iron transport proteins
Transferrin
Major protein in blood plasm synthesised by the liver, and it binds
two ferric iron per molecule . Transferrin releases iron to blood red
cells through receptor on red cell surface . 8
2- CO32- + transferrin+Fe3+ transferrin.Fe
3+.CO3
(-2ransferrin.Fe3+ .co32- + co2
2- + Fe3+
transferrin.2)Fe3+.co3
Iron lost in human body through bile secretions, menstrual flow & other
secretions. hemorrhage,
Daily iron requirements : - 10-12 mg for males 12-18mg for females
Males lose o.6 mg iron dailyNon pregnent females lose 1.2 mg-1.8 mg
iron daily Pregnent females lose 3-4 mg
daily9
Iron disteribution in normal Iron disteribution in normal adultsadults
Men Women
Hemoglobin 3050 mg 1700 mg
Myoglobin 430 mg 300 mg Enzymes )transport( 10 mg
6 mg Ferritin) storage( 750 mg 300 mg
Total 4248 mg 2314 mg
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Iron AbsorptionIron AbsorptionIn food diet :
- 1 -Iron in liver and muscle is better absorbed than iron in eggs and
vegetables , because iron is bond to phytate )inositol hexaphosphate (.
3 - Iron in wheat , corn & black beans is relatively unavailable for body use .
2 - Iron in hemoglobin is well absorbed , because it is still bond to porphyrin ring .
4 - Iron in ferritin is poorly absorbed , because the protein must firstly digested
by G.I. proteases before absorption . 5 - Released iron complexed with
sugars ,ascorbic acid,citric acid and amino acids .
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Absorption mechanismAbsorption mechanism
Cooking food facilitate iron ligand breakdown increasing iron availability
in gut .Low stomach PH allows reduction of ferric
Fe3+ to ferrous Fe2+ with presence of reductant) ? (
Major iron absorption is in small intestine mostly in the duodenum .
Exess bicarbonate secreated by pencreas oxidises ferrous Fe2+ to
ferric Fe3 +
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Three hypothesis for Three hypothesis for absorptionabsorption
1 – The mucosal blook hypothesis- :
Fe3+
Fe2+
(H)
Fe2+
Fe3+
Apoferritin
Apoferritin
(O)
Ferritin
Fe2+ Fe2+
Fe3+
Transferrin
To liver for
storage
To bone marrow for use
Small intestine
Mucosal cell Blood
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22 – – Active transport hypothesisActive transport hypothesis
Fe 3+
Fe 3+
Fe 2+
Fe 2+Fe 2+
Endogenous ligands
macromolecules
(H)
(O)Biological energy
compounds ATP
Transferrin
Lumen of
intestine
Mucosal cell
Blood
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33 – – The ion-chelate hypothesisThe ion-chelate hypothesis
Fe3+
Fe2+
Endogenous ligands
Fe-chelate
Ferritin )storag (
Fe-chelate
Storage
Transferrin
R.B.CExcreation
Fe3+
Lumen of
intestine
Mucosal cell
Blood
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