Biochemical Properties of Debranching Enzyme from Bacillus sp.CBB272

Abstract:

Debranching enzymes are essential for starch saccharification processes with their activity for cleavage of 1,6-glucoside linkage in starch molecules.In this study,a novel debranching enzyme from the thermophilic Bacillus sp.CBB272 was purified using the combination of ammonium sulfate precipitation,weak ion-exchange and strong ion-exchange.The purified enzyme possessed the relative molecular weight of 70 kD on SDS-PAGE.The enzyme exhibited the maximal activity at 70℃ and pH 6.0 with excellent stabilities at a temperature range from 30 ℃ to 70 ℃ and pHs from 4.5 to 9.0.At pH 6.0 and 50 ℃ its Km and Vmax for amylopectin were 4.0324 mg/mL and 0.1841 mg/(min·mL),respectively.The enzyme was strongly activated by Ca2+,Mg2+ and Mn2+ and Ca2+ significantly increased its thermostability.