Purification and properties of mannanase from Oerskovia xanthineolytica

Abstract

A microorganism, identified as Oerskovia xanthineolytica, which is capable of growing on Saccharomyces cerevisiae mannan as a carbon source has been isolated. When grown on yeast mannan, the microorganism secretes an α-mannanase into the culture medium. The α-mannanase purified by chromatography with phenyl-Sepharose CL-4B, DEAE-Sephacel, and by gel-filtration on Sephacryl S-300 gave a single band on nondenaturing polyacrylamide gel electrophoresis and a single precipitation line with antibodies raised against the purified enzyme. The purified α-mannanase could be dissociated into several polypeptides depending on the denaturation conditions of protein. The molecular weight of the enzyme was estimated as over 1,500,000 and the sedimentation coefficient (S 20,w) was 16.4 s. The enzyme showed optimal activity at pH between 7.0 to 8.0 and optimum temperature at 50°C. The enzyme seemed to be Ca 2+-dependent. The enzyme was activated by cysteine and sulfhydryl reagents. The enzyme was strongly inactivated by Zn 2+, Fe 2+, and Cu 2+, and completely inhibited by Ni 2+, Hg 2+, iodoacetic acid, EDTA, and cetyltrimetyl ammonium bromide. The purified enzyme hydrolyzed p-nitrophenyl α-mannopyranoside, α-1,2-mannopyranosyl- d-mannopyranose, and α-1,3-mannopyranosyl- d-mannopyranose. The enzyme could also completely disintegrate the antigenic activities of yeast mannan prepared from S. cerevisiae.