Essential and trace ions Ions with biochemical functions and have deficiency syndrume are : Iron and Iodide Ions studied are : iodide, copper,zinc,sulfur,chromium ,manganese,selenium, etc. ,iron

Iron :- First : Hemoproteins i – an electron carrier 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 .

An respiratory Enzyme, where iron is complexed (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 .

( 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.

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 .

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 .

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+

b – Iron transport proteins 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.

Daily iron requirements : - 10-12 mg for males 12-18mg for females 2- CO32- + transferrin+Fe3+ 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

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

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 .

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 .

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

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

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