engleski

Kristalizacija i strukturno istraživanje kobaltovog i niklovog bromo-derivata ljudskog inzulina

Insulin is structured as a two polypeptide chains, chain A consists of 21 and chain B of 30 amino acids. In the absence of metal ions native insulin crystallizes as a dimer but in the presence of zinc ions and some other cations three insulin dimers assemble into a hexamer. There are three forms of insulin hexamers: T6, T3R3f and R6 1. These forms of insulin are used in therapeutc preparations for the control of type 1 diabetes mellitus. Due to its big medical importance structural data for more than two hundred human insulin derivatives can be found in the Protein Data Bank [2]. As a part of our ongoing research on the crystallization and structural studies on human insulin derivatives [3] in the present study cobalt and nickel were crystallized in high bromide concentration. Single crystals of the cobalt and nickel bromo-derivative of human insulin were grown by the hanging drop vapour diffusion method using Zn-free insulin (Figure 1). Diffraction data were collected at the ELETTRA Synchrotron, beam line XRD-1. The cobalt insulin derivative belongs to the trigonal crystal system while nickel derivative belongs to the tetragonal crystal system. Optimal crystallization conditions, coordination of cobalt and nickel ions in hexamer and conformation of the insulin molecule will be discussed.

insulin ; cobalt ; nickel

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