Exo-1,4-β-mannanase from Aeromonas hydrophila

Publisher Summary A novel exo-l,4-β-mannanase was isolated from the culture fluid of strain No. F-25 of Aeromonas hydrophila . The enzyme removes mannobiose residues successively from the nonreducing end of the 1,4-β-mannan link in polysaccharides of three or more 1,4-β-1inked D-mannose units. It has no action on mannobiose, mannosylmannitol, and p -nitrophenyl- β-D-mannopyranoside. The organism also secretes an endo-l,4-β-mannanase in addition to the exo-l,4-β-mannanase in the culture fluid. This chapter discusses the assay methods and purification procedure of exo-l,4-β-mannanase. The exo-l,4-β-mannanase possesses the ability to carry out transglycosylation, in that the enzyme attacks mannotriose to give a small amount of mannopentaose in addition to mannobiose and mannose, and acts on mannotetraose to form a small amount of mannohexaose with mannobiose, in the early stages of the reaction. The enzyme cannot cleave mannobiose, mannosylmannitol, and p -nitrophenyl-β-D-mannopyranoside. The exo-1,4-β-mannanase from strain No. F-25 of Aeromonas hydrophila is a novel glycosidase that successively removes the mannobiose residue from the nonreducing end of the 1,4-β-mannan molecule. The enzyme is, therefore, classified as 1,4-β-D-mannan mannobiohydrolase.