For the first time, a beta-1,3-glucanase was isolated from the gut of sea cucumber. The enzyme was purified to homogeneity by ammonium sulfate precipitation, ion exchange chromatography with diethylaminoethyl (DEAE)-Sepharose CL-6B, hydrophobic interaction chromatography with Butyl-Sepharose and preparative electrophoresis with polyacrylamide gel electrophoresis (PAGE). The molecular weight of the purified enzyme was estimated to be 37.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme exhibited optimum activity at pH 5.5 and 40 degrees C. The enzyme showed high pH stability within the range of pH 5.0-8.0 and thermostability up to 40 degrees C. The enzyme activity was markedly activated by Mn2+, whereas strongly inactivated by Cu2+ and Ag+. The K-m and V-max of the beta-1,3-glucanase were 19.8 mu g ml(-1) and 2000 mu g min(-1) mg(-1), respectively. The amino acid sequences of three segments of the purified enzyme were acquired by mass spectrometer method, which did not have any homology with previously described echinoderm beta-1,3-glucanases, suggesting that it may be a novel member of echinoderm beta-1,3-glucanase. (C) 2008 Elsevier Ltd. All rights reserved.