Leucocyte alpha-1,4- and alpha-1,6-glucosidase activities towards oligosaccharides in late onset glycogenosis type II.
We describe the partial characterization and some properties of leucocyte alpha-glucosidase towards disaccharides with the alpha-1,4 (maltose) and alpha-1,6-glucosidic linkage (isomaltose) and tetrasaccharides with the alpha-1,4 (maltotetraose) and alpha-1,6-glucosidic linkage (tetrasaccharide, Glc alpha 1----6Glc alpha 1----4Glc alpha 1----4Glc, which was isolated from the urine of a patient with glycogenosis type II). Leucocyte alpha-glucosidase showed optimal activity towards all four oligosaccharides under two conditions, acidic (pH 4.0-4.5) and neutral (pH 6.0-6.5) regions. Our comparative studies on enzyme kinetics showed that leucocyte alpha-glucosidase was able to hydrolyze both the 1----4 isomers and the 1---6 isomers at acidic and neutral pH. Acid alpha-glucosidase could hydrolyze maltose about 10 times faster than isomaltose, and maltotetraose about 5 times faster than tetrasaccharide isolated from urine. In leucocytes of the patient with late onset glycogenosis type II, acid alpha-glucosidase activities towards maltose, isomaltose, maltotetraose and tetrasaccharide isolated from urine showed 75.3%, 67.4%, 76.5% and 41.4% of normal control values, respectively. Neutral alpha-glucosidase activities towards these four oligosaccharides were normal. Tetrasaccharide with alpha-1,6-glucosidic linkage might be accumulated by the impaired hydrolysis in the circulation as well as the leakage of undegraded glycogen to the circulation from the affected muscle.
Kuriyama
M
M
Third Department of Internal Medicine, Kagoshima University School of Medicine.
Hiwatari
R
R
Osame
M
M
Igata
A
A
D000328:Adult; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006009:Glycogen Storage Disease Type II / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D000520:alpha-Glucosidases / Q000097:blood*
D009844:Oligosaccharides; D000520:alpha-Glucosidases