a short notes on Insulin of human body

                                       Human Insulin 

Human insulin is a globular protein with a molecular weight of about 5,800 kd, consisting of 51 aminoacid residues organised in two polypeptide chains (A and B), linked by two disulphide bonds. Chain A consists of 21 residues with an extra disulphide bond between A6 and A11; chain B consists of 30 aminoacids. Complete synthesis of the human insulin molecule was achieved in 196610. Insulin exists as a monomer only at low concentrations while it shows propensity to aggregate into stable dimers at higher concentrations, in aqueous solution at pH 2-8 and into hexamers in the presence of zinc ions. The hexamer, in which chain A constitutes much of the polar surface, is almost spherical in structure, with a diameter of 5 nm and a height of 3.5 nm. Polymerisation of the hormone has major pharmacological implications.