Definitions

1. noun

a nonessential amino acid; the L-enantiomer is found in proteins and is essential to the structure and function of many enzymes

“Threonine is an essential amino acid found in whey protein.”

2. noun

a nonpolar, uncharged amino acid that is one of the 20 amino acids found in proteins

“Threonine is a polar amino acid that can participate in hydrogen bonding.”