Description: Insulin is a polypeptide hormone that consists of two peptide chains bonded by two disulfide bonds. The two chains are designated A and B. The A chain consists of 21 amino acids with a third internal disulfidebond, and the B chain contains the remaining 30 amino acids. All vertebrates produce insulin and the structure is similar in these species. For example, the insulin produced in humans and porcine species differs by only one amino acid, and humans and bovine insulin differ by three amino acids. Insulin plays a crucial role in several physiological processes. These include the regulation of sugar in the body, fatty acid synthesis, formation of triglycerides, and amino acid synthesis.
Insulin also promotes the storage of glucose as glycogen in the liver. In this manner, insulin maintains glucose at a stable level in the bloodstream. Insulin is most closely associated with diabetes. Diabetes results in excess blood glucose levels (hyperglycemia) and the inability of cells to absorb glucose, which in turn deprives them of energy.