Specificity of Aeromonas Aminopeptidase toward Oligopeptides and Polypeptides

A variety of oligopeptides and polypeptides was subjected to the action of Aeromonas amino‐peptidase and the sequential release of amino acid residues was determined quantitatively. The residues that proved susceptible to hydrolysis included all hydrophobic, aromatic and basic amino acids plus proline. Aspartyl, glutamyl and cysteic acid residues were not removed from the amino‐terminus of any substrate tested, even at high enzyme concentrations but in contrast, asparagine, glutamine and aminoethylated cysteine were released. Glycine was generally resistant to hydrolysis, but was slowly released from some substrates dependent upon the adjacent residues. The specificity and ease of purification of this aminopeptidase should make it a useful tool for sequence determination.