In vitro hydrolysis of oligomannose-type sugar chains by an alpha-1,2-mannosidase from microsomes of developing castor bean cotyledons.
An alpha-1,2-mannosidase involved in the processing of N-linked oligosaccharides was prepared from the microsomal fraction of developing castor bean cotyledons. The processing alpha-mannosidase was solubilized with 1.0% Triton X-100 and purified by ion-exchange chromatography followed by two gel filtration steps. The enzyme obtained could convert Man9GlcNAc2-PA to Man5GlcNAc2-PA, but this enzyme was inactive with Man5GlcNAc2-PA, Man4GlcNAc2-PA, and p-nitrophenyl-alpha-D-mannopyranoside. The enzyme was optimally active between pH 5.5-6.0. The processing mannosidase was inhibited by deoxymannojirimycin, EDTA, and Tris ions but not by swainsonine. Structural analyses of the mannose-trimming intermediates produced by the alpha-mannosidase revealed that specific intermediates were formed during conversion of Man9GlcNAc2-PA to Man5GlcNAc2-PA.
Kimura
Y
Y
Department of Agricultural Sciences, Faculty of Agriculture, Okayama University, Japan.
Yamaguchi
O
O
Suehisa
H
H
Takagi
S
S
D017485:1-Deoxynojirimycin; D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000494:pharmacology; D005944:Glucosamine / Q000031:analogs & derivatives / Q000494:pharmacology; D006868:Hydrolysis; D008358:Mannose / Q000378:metabolism*; D008361:Mannosidases / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D008969:Molecular Sequence Data; D063245:Plant Development; D010944:Plants / Q000378:metabolism
D017485:1-Deoxynojirimycin; D004492:Edetic Acid; D008361:Mannosidases; D005944:Glucosamine; D008358:Mannose