Neutral alpha-mannosidase activity in human serum.
Two types of alpha-mannosidase (alpha-D-mannoside mannohydrolase, EC 3.2.1.24) with neutral pH optima exist in serum. The activity with an optimum between pH 6.0 and 6.4 is similar to alpha-mannosidase C, described earlier in tissues. The second activity, with a pH optimum between pH 5.2 and 5.8 is the dominant form in serum. These two forms can be differentiated from each other by gel-filtration, chromatography on DEAE-cellulose or chromatography on Concanavalin-A Sepharose. Using the chromatographic techniques, the serum type neutral activity co-elutes with the acidic forms of the enzyme. However, these two forms can be easily distinguished by effect of pH, heating or inhibition by the substrate methyl-alpha-D-mannopyranoside. The presence of the serum type alpha-mannosidase activity is discussed with respect to mannosidosis, a lysosomal storage disease.
D004186:Disaccharidases / Q000097:blood*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008361:Mannosidases / Q000097:blood* / Q000302:isolation & purification / Q000378:metabolism
D007527:Isoenzymes; D004186:Disaccharidases; D008361:Mannosidases