(Science: amino acids) One of the 20 amino acids commonly found (and directly coded for) in proteins. It is the amide at the _ carboxyl of the amino acid glutamate. Glutamine can participate in covalent cross linking reactions between proteins, by forming peptide like bonds by a transamidation reaction with lysine residues. This reaction, catalysed by clotting factor XIII stabilises the aggregates of fibrin formed during blood clotting. Media for culture of animal cells contain some 10 times more glutamine than other amino acids, the excess presumably acting as a carbon source.