Insulin
Insulin is a hormone produced by ?-cells of Langerhans islet of pancreas, which lowers plasmatic level of glycemia. Hormone with the opposite function to insulin is called glucagon. Their interference keeps value of glycemia well-balanced.
Structure of insulin
Red: carbon; green: oxygen; blue: nitrogen; pink: sulphur; blue-pink band: protein skeleton
Production of insulin:
- 1. phase: pre-proinsulin is formed in ribosomes of Langerhans islets
- 2. phase: in endoplasmatic reticulum, pre-proinsulin is changed to proinsulin, which consists of A and B chains interconnected by C-peptide (or connection peptide)
- 3. phase: proinsulin travels to secretion granules of ? -cells, where it is in Golgi apparatus cleaved into C-peptide and insulin
- 4. phase: insulin is stored till it is needed in secretory granules of β-cells
Insulin as a remedy
Insulin was discovered by a physician - Frederick Grant Banting. He started his research on dogs in 1921. With help of his assistants, medical student Ch. Best and biochemist J.B Collip, he succeeded to isolate from bovine pancreas extract effectual insulin (which they called at the beginning "isletin"). They took out a patent for their discovery and then they hand it over without charge to university in Toronto. Triumphal journey of insulin through the world started in 1922 when first insulin samples for clinical use were obtained by Boston diabetologist E. P. Joslin. The demand was continuously increasing and Toronto laboratory was not able to cover it. Thus, company Eli Lilly in Indianopolis took over the production of insulin. Insulin has spread world widely, in our country is has been produced since 1926. In 1923, Banting and Maclead (professor of Toronto University, under whose patronage the Banting's experiments were carried out) were awarded by the Nobel Prize.
Biochemical composition was elucidated by Frederik Sanger and co-workers in 1955: he found out that bovine insulin is a protein, the chain A of which consists of 21 amino-acids and chain B from 30 amino-acids. Sanger was awarded by the Nobel Prize for this discovery as well (1958).
Application of insulin
Insulin is usually administered subcutaneously (under the skin). In hospital, it can be added to infusion and be administered intravenously (into the vein).
Aids for insulin application
- insulin pen
- insulin pump
- insulin syringe
