Purification of an acidic alpha-D-mannosidase from Aspergillus saitoi and specific cleavage of 1,2-alpha-D-mannosidic linkage in yeast mannan.
An acidic alpha-D-mannosidase (alpha-D-mannoside mannohydrolase, EC 3.2.1.24) has been isolated from culture filtrate of Aspergillus saitoi. The extracellular alpha-mannosidase was homogeneous in polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 51 000 and the isoelectric point pH 4.5. The purified enzyme has a pH optimum of 5.0, a Km of 0.45  mM with baker's yeast mannan and has no activity towards p-nitrophenyl-alpha-D-mannoside. The mode of action of the enzyme has been studied with baker's yeast mannan and saké yeast mannan. The enzyme cleaves specifically the 1,2-alpha-linked side chain, producing free mannose.
D001230:Aspergillus / Q000201:enzymology*; D055598:Chemical Phenomena; D002621:Chemistry; D006863:Hydrogen-Ion Concentration; D008351:Mannans / Q000378:metabolism*; D008361:Mannosidases / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D011134:Polysaccharides / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000032:analysis; D013379:Substrate Specificity; D015003:Yeasts / Q000032:analysis*; D043323:alpha-Mannosidase
D008351:Mannans; D011134:Polysaccharides; D008361:Mannosidases; D043323:alpha-Mannosidase