Structural Implications of the Peptide Bond

Abstract

Polypeptides are formed in a series of highly controlled reactions. Amino acids are polymerized into a polypeptide chain on ribosomes in the cell. Polymerization is based on the formation of amide bonds which are usually called “peptide bonds.” The chain direction is defined as pointing from the amino end (N-terminus) to the carboxyl end (C-terminus) as shown in Figure 2–2. This definition coincides with the direction of chain synthesis in vivo, which in turn corresponds to the 5′→3′-direction on the messenger RNA.