Isolation and properties of alpha-D-mannosidase from human kidney.
Alpha-D-Mannosidase activity exists in three forms that can be separated by DEAE-cellulose chromatography, alpha-D-Mannosidase was isolated from human kidney in a homogeneous state, and was purified 2100-fold, with p-nitrophenyl alpha-D-mannoside as substrate. The purified alpha-D-mannosidase was practically free from all other glycosidases tested. The Km of the synthetic substrate with the enzyme was 1 X 10(-3) M and the pH optimum 4.5. It was inhibited by heavy metals, sodium dodecyl sulphate, urea and compounds that react with the thiol groups, and was activated by Zn2+, Na+, 2-mercaptoethanol, human albumin and gamma-globulin. The mol. wt. of the enzyme was estimated to be 180 000 +/- 4500. After pretreatment with 2-mercaptoethanol and sodium dodecyl sulphate, alpha-D-mannosidase dissociated into subunits of mol. wts. of 58 000 +/- 600 and 30 000 +/- 380 respectively. Subunits of the same molecular weights were also obtained after the enzyme was heated at 100 degrees C.
D000645:Ammonium Sulfate; D004186:Disaccharidases / Q000302:isolation & purification*; D004789:Enzyme Activation; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008361:Mannosidases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D008970:Molecular Weight; D011489:Protein Denaturation
D004186:Disaccharidases; D008361:Mannosidases; D000645:Ammonium Sulfate