کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
685090 889033 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A xylose-tolerant β-xylosidase from Paecilomyces thermophila: Characterization and its co-action with the endogenous xylanase
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی تکنولوژی و شیمی فرآیندی
پیش نمایش صفحه اول مقاله
A xylose-tolerant β-xylosidase from Paecilomyces thermophila: Characterization and its co-action with the endogenous xylanase
چکیده انگلیسی

An extracellular β-xylosidase from the thermophilic fungus Paecilomyces thermophila J18 was purified 31.9-fold to homogeneity with a recovery yield of 2.27% from the cell-free culture supernatant. It appeared as a single protein band on SDS–PAGE with a molecular mass of approx 53.5 kDa. The molecular mass of β-xylosidase was 51.8 kDa determined by Superdex 75 gel filtration. The enzyme was a glycoprotein with a carbohydrate content of 61.5%. It exhibited an optimal activity at 55 °C and pH 6.5, respectively. The enzyme was stable in the range of pH 6.0–9.0 and at 55 °C. The purified enzyme hydrolyzed xylobiose and higher xylooligosaccharides but was inactive against xylan substrates. It released xylose from xylooligosaccharides with a degree of polymerization ranging between 2 and 5. The rate of xylose released from xylooligosaccharides by the purified enzyme increased with increasing chain length. It had a Km of 4.3 mM for p-nitrophenol-β-d-xylopyranoside and was competitively inhibited by xylose with a Ki value of 139 mM. Release of reducing sugars from xylans by a purified xylanase produced by the same organism increased markedly in the presence of β-xylosidase. During 24-hour hydrolysis, the amounts of reducing sugar released in the presence of added β-xylosidase were about 1.5–1.73 times that of the reaction employing the xylanase alone. This is the first report on the purification and characterization of a β-xylosidase from Paecilomyces thermophila.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Bioresource Technology - Volume 99, Issue 13, September 2008, Pages 5402–5410
نویسندگان
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