Purification and characterization of a novel exo-beta-mannanase from Aeromonas sp. F-25.
A novel exo-beta-mannanase (1,4-beta-D-mannan mannobiohydrolase) was isolated from the culture fluid of strain No. F-25 of Aeromonas hydrophila subspecies anaerogenes, and purified about 4,000-fold by ammonium sulfate precipitation and successive co.umn chromatographies. The final enzyme preparation appeared to be homogeneous on polyacrylamide gel electrophoresis. The enzyme hydrolyzed the beta-1,4-mannan link in polysaccharides of three or more beta-1,4-linked D-mannose units. The enzyme had a molecular weight of 64,000, pI of 5.9, pH optimum of 6.0, and was stable in a pH region of 5.0 to 8.5 and at temperatures below 45 degrees C. The Km values of the enzyme were 5.1 X 10(-4) M for mannotriose, 2.4 X 10(-4) M for mannotetraose and 1.3 X 10(-4) M for mannopentaose. The enzyme attacked codium and coffee mannans to give only mannobiose. Mannobiosyl- and mannotetraosyl-mannitol were hydrolyzed to produce mannobiose and mannitol, while mannobiose and mannosylmannitol were released from mannotriosylmannitol. The enzyme did not act on mannobiose, p-nitrophenyl-beta-D-mannoside, konjac glucomannan, or guar gum galactomannan. Furthermore, the enzyme catalyzed a transglycosylation reaction.
D000333:Aeromonas / Q000201:enzymology*; D055598:Chemical Phenomena; D002621:Chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D007525:Isoelectric Focusing; D008361:Mannosidases / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D013379:Substrate Specificity
D008361:Mannosidases; C034976:exo-1,4-beta-mannanase