BIOMOLECULES AND ENZYMES

Detailed explanation-1: -A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides.

Detailed explanation-2: -A polypeptide is a single linear chain of many amino acids (any length), held together by amide bonds. A protein consists of one or more polypeptides (more than about 50 amino acids long).

Detailed explanation-3: -By convention, names of peptides are always written from Ieft to right starting with the N-terminal end; a peptide that contains N-terminal glycine, followed by a histidine, fol-lowed by C-terminal phenylalanine is named gly cyl-his tidyl-phenylalanine.

Detailed explanation-4: -Any chain <25 amino acids is called an oligopeptide, a chain containing >25 amino acids is a polypeptide. The largest polypeptide contains 5000 amino acids. Most polypeptides contain less than 2000.

Detailed explanation-5: -However, chains of about 50 amino acids or more are usually called proteins or polypeptides. In its physiologically active form, a protein may be composed of one or more polypeptide chains.