these amino acids include alpha-amino-n-butyric acid , alpha-aminoisobutyric acid , norvaline , isovaline , pipecolic acid , beta-alanine , beta-amino-n-butyric acid , beta-aminoisobutyric acid , gamma-aminobutyric acid , sarcosine , n-ethylglycine , and n-methylalanine .
C0000392
beta-alanine
C0002520
amino