asparagine

An uncharged polar amino acid with the formula NH₂COCH₂CH(NH₂)COOH. Asparagine is formed by the ATP-assisted addition of ammonia to aspartic acid. The reverse of this reaction (but without ATP formation) is the route of asparagine breakdown. Because ammonia is extremely toxic to living cells, it is used to synthesize *glutamine and asparagine, in which form it can be stored for later use in amino acid synthesis.