An aminopeptidase from Agave americana,isolation and physical characterization

A new aminopeptidase was isolated from Agave americana by fractionation, chromatography and gel filtration. The mw of the enzyme, determined by different procedures was 86000 ± 1500; the enzyme had a sedimentation coefficient of 4.96 S, a diffusion coefficient of 5.2 × 10^?7 cm²/sec, a Stokes radius of 3.8 nm, a partial specific volume of 0.733 cm³/g, a frictional ratio of 1.40, a molecular absorbancy index at 280 nm of 8.36 × 10⁴, an isoelectric point of 4.53 and contained 1.25% carbohydrate. The amino acid composition of the enzyme was determined and the aminoterminal residue was identified as lysine whilst the carboxylterminal residue was either leucine or isoleucine. No subunit structure was observed for the enzyme.