Hemoglobin is a globular protein found in red blood cells that transports oxygen and carbon dioxide throughout the body. It is composed of heme groups with iron atoms that bind oxygen and protein subunits called globin. The iron in hemoglobin exists in the ferrous state, where it has six coordination sites that allow it to bind to four nitrogen atoms in the protoporphyrin ring of heme, a histidine residue on the globin, and either an oxygen or carbon dioxide molecule. Hemoglobin demonstrates allosteric behavior, where its affinity for oxygen changes in response to factors like pH, allowing it to efficiently deliver oxygen to tissues and pick up carbon dioxide.

2. HEMOGLOBIN

3. Introduction
• Hemoglobin is a protein ( Heme protein )
• Types of proteins are
globular proteins ( functional proteins )
linear proteins ( structural proteins )
• Hb is considered of globular proteins
• Mature RBCs do NOT synthesize Hb, while
immature RBCs synthesize Hb
• Mitochondria is very important for Heme
synthesis

4. • Heme = Protoporphyrin + Iron
• Protoporphyrin = Iron free Heme
• Protoporphyrin consist of 4 pyrrol rings.
• Iron have 6 coordination, 4 bind with these 4
pyrrol rings of protoporphyrin, 1 bind with
histidine from globulin and 1 is free (bind to
Oxygen , CO2 respectively)

5. STRUCTURE OF HEME

8. IRON IN HEMOGLOBIN IS FERROUS
OR FERRIC ? WHY ?
• Iron in ferrous form ( 6 coordination sites )
1) 4 bind with protoporphyrin
2) 1 bind to histidine ( globin )
3) 1 free bind to O2 or CO2 respectively
• Where in ferric form we well have one bond
missing ( malfunctional hemoglobin )
• Heme and globulin are not isolated, they bind together
by Iron

9. TYPES OF HEMOGLOBIN
NORMAL
• Different types of Hb due to different type
of globin NOT Heme
• Adult have HbA
HbA2
• Fetus Have HbF
and small amount of

12. GAS TRANSPORTATION
Why we use hemoglobin as a transporter for
oxygen ?
• Because of low solubility of oxygen in
water
• Hemoglobin have a regulatory effect on
oxygen concentration in lungs and tissues

14. ALLOSTERIC EFFECT
• When an enzyme reacts to effectors with conformational
changes that increase or reduce its activity, it is said
to show allosteric behavior
• Many substances act on Hb as an allosteric substances
• Although Hb is NOT an enzyme, but it have all the
characteristics of enzymes

16. OXYGEN

26. REFERENCES
 Lippincott's
 Online resources