Peptones or peptides are chains of amino acids formed by condensation of the a.a. PLs refer to peptide bonds Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... Diagram showing the π-bonded amino acids and the point of rotation A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ...