Purification and characterization of a novel glycogen branching enzyme from Paenibacillus sp. SSG-1 and its application in wheat bread making

Abstract

Glycogen branching enzyme contributes to the process of glycogen synthesis by creating α (1→6) branches through cleaving the α-1, 4-glycosidic bonds. An intracellular glycogen branching enzyme (named PsGBE) from Paenibacillus sp. SSG-1 was cloned and expressed. The recombinant enzyme was purified by metal-affinity chromatography, exhibited a molecular mass of 84.9 kDa. PsGBE was optimally active at pH 6.6 and 35°C. PsGBE showed high specificity to amylose, soluble starch and amylopectin. PsGBE could attack and change the structures of starch granules. Addition of PsGBE (40 U/100 g of flour) to wheat bread increased specific volume (5.85 mL/ g) and decreased crumb firmness (8.16 N) during bread storage. In addition, PsGBE could significantly retard the retrogradation and improve the quality of bread. Therefore, these properties make PsGBE highly potential application in the starch-related industries.