engleski

Crystallization and structure of two bovine insulin derivatives

Insulin is a polypeptide hormone, produced by the  -cells in the pancreas, that regulates carbohydrate metabolism and it also takes part in the metabolism of fat and proteins. Insulin is structured as two polypeptide chains, chain A consists of 21 and chain B of 30 amino acids. Bovine insulin differs in sequence from human insulin at residues A8, A10 and B30. There are three forms of insulin hexamers. These forms of insulin are used in therapeutc preparations for the control of diabetes. The crystal structure of T6 bovine insulin was described by Smith et al in 2005 [1]. It has been known for many years that native insulin is in the T3R3 form in the crystals grown in high chloride ion concentrations [2]. This work presents crystallization of two bovine insulin derivatives: in high iodine and bromine concentrations. Structural investigations on bovine bromo- and iodo-derivatives show that these halogen atoms are bound to the zinc ions. Crystals were grown by the hanging drop vapour diffusion crystallisation method. Single crystal diffraction data were collected on laboratory instrument at 100 K. The investigated insulin derivatives belong to the R3 rhombohedral space group with cell parameters a = 79.73 Å ; , c = 36.34 Å ; and a = 79.25 Å ; , c = 36.97 Å ; for the bromo- and iodo-derivative, respectively. Conformation of the insulin molecule and coordination of Zn- ions will be discussed.

bovine insulin; structure

doi: 10.1107/S0108767309096807