Purification and characterization of an ε-poly- L -lysine-degrading enzyme from an ε-poly- L -lysine-producing strain of Streptomyces albulus

. An ε-poly- L -lysine-degrading enzyme of an ε-poly- L -lysine-producing strain of Streptomyces albulus was purified and characterized . The enzyme was tightly bound to the cell membrane. After solubilization with NaSCN, the enzyme was purified to homogeneity by phenyl-Sepharose CL-4B column chromatography. The subunit molecular mass of the purified enzyme was 54 kDa. Enzyme activity was inhibited by o -phenanthroline, and could be restored in the presence of 1 mM Mg 2+ , Ca 2+ , Fe 3+ or Zn 2+ . The mode of ε-poly- L -lysine degradation was of the exo-type, and the enzyme released N-terminal L -lysines one by one. The enzyme acted on various peptides possessing L -lysine residues at the N-terminus and was classified as an aminopeptidase. ε-Poly- L -lysine-degrading activity was found in the membrane fraction of some other Streptomyces strains as well as that of Streptomyces albulus . Streptomyces virginiae IFO 12827 and Streptomyces norsei IFO 15452 exhibited high ε-poly- L -lysine-degrading activity, and both strains could produce ε-poly- L -lysine, indicating a correlation between the distribution of membrane-bound ε-poly- L -lysine-degrading enzyme and ε-poly- L -lysine-producing activity.