To explore how the substrate specificity of an aminopeptidase (Leu > Glu, Gly, Ala, Val (PreII)) from Bacillus licheniformis SWJS33 (BLAM) affects its performance in hydrolyzing different proteins, peanut protein isolate (PPI) and zein which containing 6.8% and 18.7% Leu respectively were employed as substrates. BLAM increased the degree of hydrolysis of zein more effectively than that of PPI. The aminopeptidase could significantly increase the percentages of Leu and PreII in total free amino acid compared to commercial peptidases. The amino...