L-Glutamine is an essential amino acid required by all mammalian and insect cells grown in culture. L-glutamine degrades rapidly in solution through an intramolecular cyclization reaction forming ammonia as a byproduct. HiGlutaXL™ supplement contains the stabilized dipeptide form of L-glutamine, L-alanyl-L-glutamine. L-alanyl-L-glutamine incorporates L-alanine that protects the alpha amino acid group. Aminopeptidases within the cell break the dipeptide, gradually releasing both L-glutamine and L-alanine for use by the cell. The thermostable nature of L-alanyl-L glutamine obviates the need of addition of L-glutamine at the time of use and allows liquid media to be stored at 4deg C for longer periods. TCL030 is a sterile filtered 200mM solution of L-alanyl-L-glutamine prepared in 0.85% normal saline.