Wiktionary
norvaline
n. (context amino acid English) An amino acid ''2-amino-butanoic acid'' that is not found in protein
Wikipedia
Norvaline
Norvaline (abbreviated as Nva) is an amino acid with the formula CH(CH)CH(NH)COH. The compound is an isomer of the more common amino acid valine. Like most other α-amino acids, norvaline is chiral. It is a white, water-soluble solid.