Answer:An exopeptidase activity was originally identified in several rat tissues [1], using L-aminoacyl β-naphthylamides (L-aa β-NA) and L-amino acid-7-amido-4-methylcoumarins as substrates.
Explanation:This enzyme was able to remove only basic residues (Arg and Lys) from L-aa β-NA and was consequently called aminopeptidase B.