Characterization of leucine amino peptidase from Streptomyces gedanensis and its applications for protein hydrolysis

The aim of this work was to purify and characterize the extra-cellular leucine amino peptidase (LAP) from Streptomyces gedanensis and also study its applications for protein hydrolysis. The enzyme was purified to homogeneity by ammonium sulfate fractionation and sequential chromatography steps. LAP appeared to be a monomeric enzyme with a molecular weight of similar to 75 kDa determined by sodium dodecyl sulfate poly acryl amide gel electrophoresis (SDS-PAGE). The enzyme preferentially hydrolyzed leucine p-nitroanilide followed by Met, Phe, Lys and Arg derivatives. Kinetic studies on the purified enzyme confirmed that it can hydrolyze peptide as well as ester substrates at comparable rates. This amino peptidase was highly resistant to different concentrations of various organic solvents. The characteristics of this amino peptidase, including thermo stability, organic solvent resistance, its activity against various substrates, and also it showed esterase and peptidase activity at comparable rates; identified this amino peptidase as a novel one. The specificity towards aromatic and hydrophobic amino acid residues, the solvent-resistance and thermo stability make this amino peptidase could offer interesting possibilities for various industrial applications including debittering of protein hydrolysates, peptide and ester synthesis. (C) 2011 Elsevier Ltd. All rights reserved.