Asparagine is a non-essential amino acid, which is synthesized in the human body from L-aspartate by Asparagine synthetase. Asparagine is required for the synthesis of many important cellular proteins in normal human cells. Many tumor cells do not have this capacity, due to a lack of the enzyme L-asparagine synthetase, and therefore require an exogenous supply of the amino acid. This amino acid participates in the functions of the brain and nervous system. Asparagine may come from food or be taken as a dietary supplement.