1. Protein structure

Figure 3: The bond between the two amino acids, and both end types of a polypeptide chain

Figure 3: The bond between the two amino acids, and both end types of a polypeptide chain

1.2 Proteins

A protein is a biological macromolecule made up of one or several chains of amino acids linked to each other by peptide bonds forming a polypeptide chain.

A protein is generally termed to be chain containing a large number of amino acids, whereas a peptide rather refers to small-sized chains.

1.2.1 Peptide bond

The formation of a peptide bond is catalyzed by a ribosome.

The COOH group of the amino acid n and the NH2 group of the amino acid n+1 both participate. Accordingly, at each end of protein is found:

  • The NH2 group or N-terminus of the protein (next to the first amino acid).

  • The COOH group or C-terminus of the protein (next to the last amino acid).