title: Purification and characterization of an alpha-L-rhamnosidase from Aspergillus niger.
abstract: An enzyme with alpha-L-rhamnosidase activity was purified by anion exchange chromatography from an Aspergillus niger commercial preparation. The alpha-L-rhamnosidase was shown to be N-glycosylated, and had a molecular mass of 85 kD on sodium dodecylsulfate-polyacrylamide gel electrophoresis of which approximately 12% was contributed by carbohydrate. The enzyme was optimally active at pH 4.5 and 65 degrees C. When tested towards p-nitrophenyl-alpha-L-rhamnopyranoside it showed Km and Vmax values of 2.9 mM and 20.6 U mg-1, respectively whereas it was inhibited competitively by L-rhamnose (Ki 3.5 mM). Substrate specificity studies showed alpha-L-rhamnosidase to be active both on alpha-1,2 and alpha-1,6 linkages to beta-D-glucose. Moreover, the enzyme was able to release L-rhamnose from geranyl-beta-D-rutinoside and 2-phenylethyl-beta-D-rutinoside.
authors.affiliation: Section Molecular Genetics of Industrial Microorganisms, Wageningen Agricultural University, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Manzanares
authors.forename: L H
authors.initials: LH
authors.lastname: de Graaff
authors.forename: J
authors.initials: J
authors.lastname: Visser
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D002236:Carbohydrate Conformation; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D044950:Flavanones; D005419:Flavonoids / Q000378:metabolism; D005656:Fungal Proteins / Q000302:isolation & purification*; D005960:Glucosides / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000302:isolation & purification*; D006569:Hesperidin / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D012210:Rhamnose / Q000378:metabolism; D019685:Rosales; D012431:Rutin / Q000378:metabolism; D013379:Substrate Specificity; D014920:Wine
chemical_list: D044950:Flavanones; D005419:Flavonoids; D005656:Fungal Proteins; D005960:Glucosides; D012431:Rutin; D006569:Hesperidin; D006026:Glycoside Hydrolases; C022525:alpha-L-rhamnosidase; C005274:naringin; D012210:Rhamnose