HealthWise® L-Threonine is 100% pure pharmaceutical grade amino acid powder. Threonine is needed to create glycine and serine, two amino acids that are necessary for the production of collagen, elastin and muscle tissue. It is also found in significant amounts in the heart. Did you know? The Threonine abbreviation is Thr, and its one letter code is T. The proper Threonine pronunciation is 'three-uh-need'.