Purification of glycogen debranching enzyme from porcine brain: evidence for glycogen catabolism in the brain.
Amylo-1,6-glucosidase from porcine brain was purified to homogeneity by ammonium sulfate fractionation, followed by sequential steps of liquid chromatography on DEAE-Sephacel, Sephacryl S-300, and Super Q. The purified enzyme had both maltooligosaccharide transferase and amylo-1,6-glucosidase activities within a single polypeptide chain, and the combination of these two activities removed the branches of phosphorylase limit dextrin. Based on these results, the purified enzyme was identified as a glycogen debranching enzyme (GDE). The molecular weight of the brain GDE was 170,000 by gel-filtration and 165,000 by reducing SDS-PAGE. The pH profile of maltooligosaccharide transferase activity coincided with that of the amylo-1,6-glucosidase activity (pH optimum at 6.0). The existence of GDE as well as glycogen phosphorylase in the brain explains brain glycogenolysis fully and supports the hypothesis that glycogen is a significant source of energy in this organ.
Makino
Yasushi
Y
Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan.
Omichi
Kaoru
K
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D006003:Glycogen / Q000378:metabolism*; D006004:Glycogen Debranching Enzyme System / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013552:Swine
D006004:Glycogen Debranching Enzyme System; D006003:Glycogen; C030563:amylo-1,6-glucosidase