Discovery?Characterization And Applications Of Novel Starch Debranching Enzymes

The branch of starch is negative factor of hydrolyzation,starch debranching enzymes can improve the efficiency of starch hydrolyzation.This paper is researching about two kinds of starch debranching enzymes.By using Escherichia coli express pullulanase from Thermosipho africanus and isoamylase from Sulfolobus tokodaii we got some character of these enzymes and found some applications of them.The pullulanase from Thermosipho africanus is a type I pullulanase.It's molecular weight is96.4k Da in theory,pullulanase activity is 96U/mg,optimum temperature is 70?,optimum p H=6.8.It's half pullulanase activity time is over 6 hours at 70?.But it has a high substrate specificity,so it is difficult to hydrolysis starch.The isoamylase from Sulfolobus tokodaii highly thermostable isoamylase.It's a first isoamylase be discovered which can keep half isoamylase activity over 3 hours at 90?.The KEGG data base note that this protien is a glycogen debranching enzyme,but for the substrate specificity we found it has really low activity on glycogen it is about 3.1% of amylopectin.It's molecular weight is 82.9k Da in theory,isoamylase activity is 6.4U/mg,optimum temperature is 85?,optimum p H=5.5.The low substrate specificity lead it has 5% cativity on amylose,so this isoamylase can also hydrolysis ?-1,4-glycosidic linkage.It can be used for starch pretreatment with 90? and can get short amylose(DE>5)...