Hemoglobin (Hb) is the iron containing chromoprotein forming 95% of dry weight of RBC .Average hemoglobin (Hb) content in blood is 14 to 16 g/dL. In adult males it is 15 g/dL and in adult females it is 14.5 g/dL .Felix Hope Seyler in 1862 isolated pure Hemoglobin.Christian Bohr in 1904 discovered that hemoglobin is the transporter of oxygen.In 1912 Kutster established the structure of hemoglobin.Hans Fischer synthesized heme in laboratory in 1920 (Nobel prize, 1930).In 1945, Linus Pauling (Nobel prize, 1954) described abnormal hemoglobins.Max Perutz (Nobel Prize, 1962) studied the 3D structure of Hemoglobin.
Hemoglobin is a globular heme protein in vertebrate red blood cells and in the plasma of many invertebrates that carries oxygen and carbon dioxide; heme group binds oxygen and carbon dioxide and as well as imparts red color to the blood; also spelt as hemoglobin.Red colored conjugated protein (made up of heme and Globin) present inside the RBCNormal Hb% in adult male is 14 to 16 gm.Approximately 6.25 gm of Hb are synthesized and destroyed every day.Heme structure does not vary from species to species.It is the basic protein globin that varies in amino acid composition and sequence in different species.Globin is rich in Histidine and lysine.
Structure of Hemoglobin: Hemoglobin is a conjugated protein. It consists of a
protein combined with an ironcontaining pigment. The protein part is globin and the iron containing pigment is heme. Heme also present in the structure of myoglobin ie oxygenbinding pigment in muscles and neuroglobin ie oxygenbinding pigment in brain. Heme is iron porphyrin compound.Iron is present in ferrous (Fe2+) form. It is in unstable or loose form. In some abnormal conditions,the iron is converted into ferric (Fe3+) state, which is a stable form.The pigment part of heme is called porphyrin. It is formed by four pyrrole rings (tetrapyrrole) called, I, II, III and IV. The pyrrole rings are attached to one another by methane (CH4) bridges.The iron is attached to ‘N’ of each pyrrole ring and ‘N’ of globin molecule.Globin contains four polypeptide chains. Among the four polypeptide chains, two are βchains and two are α-chain /α-chain is made up of 141 aminoacids β-chain is made up of 146 aminoacids.
Varieties of normal human Hb are
HemoglobinA1 (two α-chains and β-chains)
HemoglobinF (two α-chains and ¥-chains)
HemoglobinA2 (two α-chains and delta-chains)
Embyonic Hemoglobin (two α-chains and €-chains)
Hemoglobin-A3 (Altered from Hb-A found in old red cells)
HemoglobinA1C (Glycosylated Hb, present in concentration of 3-5% of total Hb). In diabetes mellitus it is increased to 6 to 15%.
Functions:
1 Hemoglobin as oxygen carrier:The main function of hemoglobin is to carry oxygen from the lungs to all the tissues of the body. This is due to the affinity of hemoglobin for oxygen. When hemoglobin comes in contact with oxygen, it combines with it and form oxy-hemoglobin. This is a week bond. When blood reaches to tissues, where oxygen is deficient, the bond is broken and oxygen diffuses out to tissues.
2.Hemoglobin as carbon dioxide carrier:Some of carbon dioxide is transported from tissues to lungs through hemoglobin. Although the majority of it is transported via plasma but still it carries some of CO2 to lungs.
3.Give color of blood:The red color of blood is due to hemoglobin. When red blood cells are separated from the blood, the red color disappears. This means that the red color of blood is due to red blood cells. Hence the name red blood cells is given to it. And as we know that hemoglobin is present inside red blood cells, therefore it gives red coloration to RBCs
4.Buffering action:Hemoglobin also acts as a buffer.Buffer means to resist change in pH.Blood has 7.4 pH and it remains in the narrow range.Because, if it changes the life of the person may be endangered.Therefore, hemoglobin plays very important role in keeping the pH of blood constant.
5.Erythrocyte metabolism:Hemoglobin plays an important role in the modulation of erythrocyte metabolism.
6.Interaction with drugs:Not only for oxygen, but hemoglobin act a very important role the transport of various drugs to their site of action.
7. Physiological active catabolites:Hemoglobin is a source of various physiological active catabolites.
Hemoglobin is a globular heme protein in vertebrate red blood cells and in the plasma of many invertebrates that carries oxygen and carbon dioxide; heme group binds oxygen and carbon dioxide and as well as imparts red color to the blood; also spelt as hemoglobin.Red colored conjugated protein (made up of heme and Globin) present inside the RBCNormal Hb% in adult male is 14 to 16 gm.Approximately 6.25 gm of Hb are synthesized and destroyed every day.Heme structure does not vary from species to species.It is the basic protein globin that varies in amino acid composition and sequence in different species.Globin is rich in Histidine and lysine.
Structure of Hemoglobin: Hemoglobin is a conjugated protein. It consists of a
protein combined with an ironcontaining pigment. The protein part is globin and the iron containing pigment is heme. Heme also present in the structure of myoglobin ie oxygenbinding pigment in muscles and neuroglobin ie oxygenbinding pigment in brain. Heme is iron porphyrin compound.Iron is present in ferrous (Fe2+) form. It is in unstable or loose form. In some abnormal conditions,the iron is converted into ferric (Fe3+) state, which is a stable form.The pigment part of heme is called porphyrin. It is formed by four pyrrole rings (tetrapyrrole) called, I, II, III and IV. The pyrrole rings are attached to one another by methane (CH4) bridges.The iron is attached to ‘N’ of each pyrrole ring and ‘N’ of globin molecule.Globin contains four polypeptide chains. Among the four polypeptide chains, two are βchains and two are α-chain /α-chain is made up of 141 aminoacids β-chain is made up of 146 aminoacids.
Varieties of normal human Hb are
HemoglobinA1 (two α-chains and β-chains)
HemoglobinF (two α-chains and ¥-chains)
HemoglobinA2 (two α-chains and delta-chains)
Embyonic Hemoglobin (two α-chains and €-chains)
Hemoglobin-A3 (Altered from Hb-A found in old red cells)
HemoglobinA1C (Glycosylated Hb, present in concentration of 3-5% of total Hb). In diabetes mellitus it is increased to 6 to 15%.
Functions:
1 Hemoglobin as oxygen carrier:The main function of hemoglobin is to carry oxygen from the lungs to all the tissues of the body. This is due to the affinity of hemoglobin for oxygen. When hemoglobin comes in contact with oxygen, it combines with it and form oxy-hemoglobin. This is a week bond. When blood reaches to tissues, where oxygen is deficient, the bond is broken and oxygen diffuses out to tissues.
2.Hemoglobin as carbon dioxide carrier:Some of carbon dioxide is transported from tissues to lungs through hemoglobin. Although the majority of it is transported via plasma but still it carries some of CO2 to lungs.
3.Give color of blood:The red color of blood is due to hemoglobin. When red blood cells are separated from the blood, the red color disappears. This means that the red color of blood is due to red blood cells. Hence the name red blood cells is given to it. And as we know that hemoglobin is present inside red blood cells, therefore it gives red coloration to RBCs
4.Buffering action:Hemoglobin also acts as a buffer.Buffer means to resist change in pH.Blood has 7.4 pH and it remains in the narrow range.Because, if it changes the life of the person may be endangered.Therefore, hemoglobin plays very important role in keeping the pH of blood constant.
5.Erythrocyte metabolism:Hemoglobin plays an important role in the modulation of erythrocyte metabolism.
6.Interaction with drugs:Not only for oxygen, but hemoglobin act a very important role the transport of various drugs to their site of action.
7. Physiological active catabolites:Hemoglobin is a source of various physiological active catabolites.
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