کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8327223 1540200 2018 28 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Sequence analysis and biochemical properties of an acidophilic and hyperthermophilic amylopullulanase from Thermofilum pendens
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Sequence analysis and biochemical properties of an acidophilic and hyperthermophilic amylopullulanase from Thermofilum pendens
چکیده انگلیسی
The acidophilic and thermophilic pullulanases have many potential applications in the processes of starch liquefaction and saccharification. In this study, a gene encoding an amylopullulanase from Thermofilum pendens (TPApu) was heterologously expressed in Escherichia coli. Although TPApu possessed the same continuous GH57N_Apu domain and the succeeding α-helical region as other two amylopullulanases from Staphylothermus marinus (SMApu) and Caldivirga maquilingensis (CMApu), it only showed maximal amino acid identities of 25.7-28.7% with CMApu and SMApu. The purified TPApu appeared as a single band of SDS-PAGE with a molecular mass of 65.5 kDa and exhibited the maximal activity at pH 3.5 and 95-100 °C. TPApu had the highest catalytic efficiency towards pullulan (kcat/km, 8.79 s−1mL mg−1) and α-cyclodextrin (kcat/km, 0.36 s−1 mM−1). In the initial stages, the ring-opening reactions of γ-cyclodextrin, 6-O-glucosyl-β-cyclodextrin, 6-O-maltosyl-β-cyclodextrin and the debranching reactions of 6-O-maltooctaosyl-β-cyclodextrin were firstly catalyzed. In the subsequent reactions, a serial of maltooligosaccharides were produced. As the most acidophilic amylopullulanase among thermophilic pullulanases reported to date, TPApu preferred to debranch the DP6-12 side chains of amylopectin at pH 4.5 and 100 °C.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Biological Macromolecules - Volume 114, 15 July 2018, Pages 235-243
نویسندگان
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