the antiserum appears to be directed to the cooh-terminus of the peptide , as it fails to cross-react with met5-enkephalin , met5-enkephalin-arg6 , met5-enkephalin-arg6-arg7 , met6-enkephalin-lys6 , and leu-enkephalin .
C0014298
enkephalin
C0014294
leu-enkephalin