Studies on cellulases of a phytopathogenic fungus, Pyricularia oryzae cavara. II. Purification and properties of a beta-glucosidase.
Three components (GA, GB-1, and GB-2) of beta-glucosidase were detected in the culture filtrate of Pyricularia oryzae grown in a cellulose or cellulose derivative medium. Among them, GB-1 was induced most strongly. Purified GB-1 was homogeneous on polyacrylamide gel electrophoresis and showed an approximately 1,400-fold increase of specific activity over the starting material. The molecular weight was determined to be 240,000 by sodium dodecyl sulfate-gel electrophoresis. A similar value was also obtained by sucrose density gradient centrifugation. The enzyme contained a high proportion of acidic amino acids and mannose, and the isoelectric point of the enzyme was pH 4.15. The enzyme had a pH optimum of 5.5 and a temperature optimum at 55 degrees C. beta-Glucosidase activity was inhibited by Mn2+, Cu2+, Hg2+, p-chloromercuribenzoate, and glucono-delta-lactone. The enzyme split off glucose units one by one from the nonreducing ends of not only beta-glucooligosaccharides but also some beta-glucans, such as carboxymethylcellulose, laminaran, pustulan, and zeagallan. The affinity for cello- and laminari-oligosaccharides tended to increase in parallel with the chain length.
D000596:Amino Acids / Q000032:analysis; D002413:Cations, Divalent / Q000494:pharmacology; D002475:Cellobiose / Q000378:metabolism; D002729:Chloromercuribenzoates / Q000494:pharmacology; D005936:Glucans / Q000378:metabolism; D005942:Gluconates / Q000494:pharmacology; D005959:Glucosidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007783:Lactones / Q000494:pharmacology; D003904:Mitosporic Fungi / Q000201:enzymology*; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D001617:beta-Glucosidase / Q000302:isolation & purification / Q000378:metabolism*
D000596:Amino Acids; D002413:Cations, Divalent; D002729:Chloromercuribenzoates; D005936:Glucans; D005942:Gluconates; D007783:Lactones; D002475:Cellobiose; D005959:Glucosidases; D001617:beta-Glucosidase