The insulin molecule contains 51 amino acids; it is made up of two peptide chains linked by disulphide bonds. Although it is active as a monomer, during its biosynthesis and storage it assembles to dimers and, in the presence of zinc, to hexamers. X-ray analysis has revealed the 3-dimensional structure of the insulin molecule in its hexameric, dimeric and monomeric states. Two main conformations of insulin which differ in the extent of helix in the B chain (B9-B20 and B1-B20, respectively) have been identified. Other variations are seen in insulin when dimeric or monomeric. Reagents such as chloride and phenol govern the conformations present in the insulin hexamers and this can influence the behaviour and properties of insulin preparations employing them.

No abstract

No abstract

The three-dimensional structure of uncomplexed natural sequence recombinant human growth hormone has been determined to 2.5 A. resolution by means of X-ray crystallographic techniques. The structure was solved using molecular replacement with a model of a hGH variant. The crystallographic refinement of the structure gave a final R-factor of 21.3% for data in the range from 8 to 2.5 A.

No abstract