Chay Sirirattanachatchawan. Characterization of Recombinant Glycogen Debranching Enzyme from corynebacterium glutamicum and Application for Resistant Starch Production. Master's Degree(Biotechnology). Chulalongkorn University. Office of Academic Resources. : Chulalongkorn University, 2018.
Characterization of Recombinant Glycogen Debranching Enzyme from corynebacterium glutamicum and Application for Resistant Starch Production
Abstract:
Glycogen debranching enzyme (EC 2.4.1.25/EC 3.2.1.33) catalyzes a hydrolysis of α-1,6 glycosidic bond and a transfer α-1,4 glucan from donor molecules to acceptor molecules. The objectives of this research are to characterize a glycogen debranching enzyme from Corynebacterium glutamicum (CgGDE) and optimize resistant starch (RS) type 3 production using recombinant CgGDE. Recombinant CgGDE was expressed in Escherichia coli BL21 (DE3) and successfully purified by DEAE FFTM column. The calculated molecular weight of CgGDE was approximately 95 kDa and the protein existed as a trimer as analyzed by size exclusion chromatography. CgGDE showed the highest activity on amylopectin followed by glycogen, soluble starch and amylose. The enzyme also showed transferase activity when assayed using G2-βCD as substrate. When treated pea, tapioca, corn, rice and potato starch with CgGDE, %RS was dramatically increased compared with non-treated starch. Tapioca starch was then used for upscale production of RS. The result showed that it yielded 90 % of RS. Based on differential scanning calorimetry (DSC) analysis, corn and rice were A-type starch, which showed the lowest enthalpy (ΔH) at 11.62 and 10.28 J/g, respectively. Tapioca and potato starch were B-type starch, with the highest enthalpy (ΔH) at 26.42 and 22.29 J/g, respectively. Pea starch was C-type starch and had the enthalpy (ΔH) of 14.14 J/g. CgGDE treated tapioca, potato, corn and rice starches showed lower onset temperature than that of non-treated starches. Moreover, the conclusion temperature of all types of starches treated with CgGDE, including pea starch, increased when compared with that of non-treatment starches.