An endopeptidase has been purified from sprouts of bamboo (Pleioblastus hindsii Nakai) to electrophoretic homogeneity by four. purification steps. Its M-r was estimated to be 82 kDa by SDS-PAGE. Enzyme activity was inhibited strongly by diisopropyl fluorophosphate, and weakly by p-chloromercuriphenylsulfonic acid, but not at all by EDTA or pepstatin, indicating that it was a serine protease. The preferential cleavage sites for this protease were found to be large hydrophobic and amide residues at the P-1 position. The specificity of the bamboo serine protease differed from that of cucumisin [EC 3.4.21.25], which cleaved the charged amino acid residues at the P-1 position. (C) 2000 Elsevier Science Ltd. All rights reserved.