Properties of yeast debranching enzyme and its specificity toward branched cyclodextrins
Article first published online: 3 MAR 2005
European Journal of Biochemistry
Volume 206, Issue 2, pages 345–348, June 1992
How to Cite
TABATA, S. and HIZUKURI, S. (1992), Properties of yeast debranching enzyme and its specificity toward branched cyclodextrins. European Journal of Biochemistry, 206: 345–348. doi: 10.1111/j.1432-1033.1992.tb16933.x
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received November 5, 1991/January 27, 1992) – EJB 91 1490
Debranching enzyme was purified from Saccharomyces cerevisiae by DEAE-cellulose, ω-aminobutyl agarose and hydroxyapatite column chromatography. The activity of the eluent was monitored by the iodine-staining method which detects both the direct and indirect debranching enzymes. The elution profiles at every step showed a single peak with no shoulder. The crude and the purified enzyme preparations gave a single activity band with the same mobility on PAGE. The crude product produced 80% glucose compared to reducing sugar from glycogen-phosphorylase-limited dextrin while the partially purified and purified preparations produced 100% glucose.
The activity of the purified enzyme was characterized and compared with that of the rabbit muscle enzyme by using various branched cyclodextrins as substrates. Both enzymes hydrolyzed 6-O-α-d-glucosyl cyclodextrins to glucose and cyclodextrins, but did not act on 6-O-α-maltosyl cyclomaltoheptaose. The yeast enzyme gave rise to glucose as a sole reducing sugar from 6-O-α-maltotriosyl cyclomaltoheptaose and 6-O-α-maltotraosyl cyclomaltoheptaose, indicating that maltosyl and maltotriosyl transfers, respectively, had occurred, prior to the action of amylo-1,6-glucosidase.
6-O-α-d-Glucosyl cyclomaltoheptaose and 6-O-α-d-glucosyl cyclomalto-octaose, respectively, were better substrates than glycogen-phosphorylase-limited dextrin for the yeast and muscle enzymes. The yeast enzyme released glucose at a similar rate from 6-O-α-maltotriosyl cyclomaltoheptaose as from 6-O-α-maltotetraosyl cyclomaltoheptaose, but considerably lower rates than that from limit dextrin.
The yeast debranching enzyme appears to be exclusively oligo-1,41,4-glucantransferase-amylo-1,6-glucosidase and does not have isoamylase.