Alpha helix

structure of proteins Secondary (such as bet a and harmonica), stabilized by hydrogen bonds. Recalls cylinder shape formed by narrow, right-twisted spring. The walls of the cy linder creates a polypeptide chain and side chains (substituents) sticking out. Every four amino acids in the polypeptide chain hydrogen bond is formed between the carboxyl group of one amino acid and the amino group of another. Stroke helix occurs at 0.54 nm.