Essential and trace ions

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Essential and trace ions

• Ions with biochemical functions and have
  deficiency syndrume are
• Iron and Iodide

Ions
studied are iodide, copper,zinc,sulfur,chrom
ium ,manganese,selenium, etc. ,iron
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Iron

• Iron functions in respiratory chain are
• i an electron carrier
• ii- transport of molecular oxygen

Most iron is associated with protiens
- First Hemoproteins
responsible for respiration Two group proteins
and for transport oxygen .
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(a) Cytochrome c
An respiratory Enzyme, where iron is complexed
covalently with the protein portion in a
porphyrin ring ( heme ring ) .

Iron act as electron carrier by changing from
ferrous to the ferric form and reversibly .

Cytochrome c role is in oxidation reduction
process of iron .
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( b ) Hemoglobin and myoglobin
Hemoproteins which store and/or transport Oxygen

- Myoglobin
An oxygen carrying protein .
. A single polypeptide with one oxygen binding
site
Binds and releases oxygen through changes in
oxygen conc. in sarcoplasma of skeletal
muscle cells.
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Hemoglobin
Found 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 .
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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 proteins
Body 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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Hemosiderin
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.
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2- CO32- transferrinFe3
transferrin.Fe 3.CO3
( -2ransferrin.Fe3 .co32- co22- Fe3
transferrin.2(Fe3.co3
Daily iron requirements - 10-12 mg for males
12-18mg for females
Iron lost in human body through bile secretions,
menstrual flow other secretions. hemorrhage,
Males lose o.6 mg iron daily
Non pregnent females lose 1.2 mg-1.8 mg iron
daily
Pregnent females lose 3-4 mg daily
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Iron disteribution in normal adults
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 Absorption
In 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 ) .
2 - Iron in hemoglobin is well absorbed ,
because it is still bond to porphyrin ring .

3 - Iron in wheat , corn black beans is
relatively unavailable for body use .
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 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 ( ? )
Exess bicarbonate secreated by pencreas oxidises
ferrous Fe2 to ferric Fe3
Major iron absorption is in small intestine
mostly in the duodenum .
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Three hypothesis for absorption
1 The mucosal blook hypothesis -
Apoferritin
Transferrin
Apoferritin
To liver for storage
Fe3
Fe3
Fe3
Ferritin
(H)
(O)
To bone marrow for use
Fe2
Fe2
Fe2
Fe2
Small intestine
Mucosal cell
Blood
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2 Active transport hypothesis
Endogenous ligands
Fe 3
Fe 2
(H)
(O)
Biological energy compounds ATP
Fe 2
Fe 2
Fe 3
Transferrin
macromolecules
Lumen of intestine
Mucosal cell
Blood
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3 The ion-chelate hypothesis
Endogenous ligands
Storage
Transferrin
Fe2
Fe3
Fe-chelate
Fe-chelate
Fe3
R.B.C
Excreation
Ferritin (storag )
Lumen of intestine
Blood
Mucosal cell