Role of the carbohydrate moiety of a glucoamylase from Aspergillus awamori var. kawachi in the digestion of raw starch.
The digestion of raw starch by a glucoamylase (GA MU-H) from a mutant strain of Aspergillus awamori var. kawachi was closely correlated with mannoside chains O-linked to the Gp-I region (A470-V514), but not sugar chains N-linked to catalytic GAI' domain of GA MU-H. The partial replacement of mannose residues by glucose residues led to a significant decrease raw starch digestion. By the substitution of D2O for H2O in the reaction mixture, the raw starch digestion of GA MU-H decreased to 80% of that at 30 degrees C, although the rate of hydrolysis of soluble starch by and the ability to bind beta-cyclodextrin of GA MU-H were unchanged. Glycerol, known as an antichaotropic reagent, decreased the raw starch digestion of GA MU-H significantly. However, it did not have any effect on the enzymatic activity for soluble starch when soluble starch was the substrate. The efficient digestion of raw starch with raw starch-digesting glucoamylase needed the mannoside chains O-linked to the Gp-I region, which were suggested to contribute to digestion of raw starch through the interaction with water.
Goto
M
M
Department of Agricultural Chemistry, Kyushu University, Fukuoka, Japan.
Kuwano
E
E
Kanlayakrit
W
W
Hayashida
S
S
D000581:Amidohydrolases / Q000378:metabolism; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D003208:Concanavalin A / Q000737:chemistry; D017666:Deuterium Oxide; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry / Q000378:metabolism*; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D005990:Glycerol / Q000737:chemistry; D006868:Hydrolysis; D008358:Mannose / Q000737:chemistry / Q000378:metabolism; D008361:Mannosidases / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D013213:Starch / Q000378:metabolism*; D013329:Structure-Activity Relationship; D043323:alpha-Mannosidase
D002241:Carbohydrates; D003208:Concanavalin A; D013213:Starch; D008361:Mannosidases; D043323:alpha-Mannosidase; D005087:Glucan 1,4-alpha-Glucosidase; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D005947:Glucose; D017666:Deuterium Oxide; D005990:Glycerol; D008358:Mannose