5 . Antibodies Gamma globulins present in blood . 6 . Blood protein Albumms , haemoglobin and fibrinogen .
Haemoglobin is a globular protein . Its prosthetic group is heme . It Contains 574 amino acid units distributed in four polypeptide chains .
Two chains containing 141 amino acid residues each are called α-chains and the two chains containing 146 amino acid residues are called β-chains .
Sickle cell anaemia is caused by defective haemoglobin obtained by replacing only one amino acid , i . e ., glutamic acid by valine .
Denaturation of Proteins
The process that changes the three dimensional structure of native proteins is called denaturation of proteins . It can be caused by Change in pH , addition of electrolyte , heating or addition of solvent like water , alcohol or acetone .
Tests of Proteins ( i ) Biuret Test Protein solution + NaOH + dil . CuSO4 → pink or violet colour .
( ii ) Millon ’ s Test Protein solution + Millon ‟ s reagent → pink colour
Millon ’ s reagent is solution of mercuric nitrate and nitrite in nitric acid containing traces of nitrous acid .
( iii ) Iodine reaction Protein solution + iodine in potassium iodide solution → yellow colour .