A Chain: The Bond Between Insulin And B Chain

Insulin has a primary structure consisting of an A chain and a B chain, where the A chain is made up of 21 amino acids and the B chain is made up of 30 amino acids (Weiss et al, 2014). The amino acid cysteine will form S-S, or disulfide, bonds with the sulfur attached to another cysteine amino acid. These bonds are considered part of the primary structure because they are covalent bonds, and insulin has two disulfide bonds between the A chain and the B chain (See Figure 1). The protein insulin consists only of alpha helices. The A chain consists of two alpha helices separated by a straighter portion that allows the two helices to lie alongside one another (Steane, 2017). The B chain consists of one larger alpha helix and connects to both