کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
70009 48805 2013 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Biochemical and molecular characterization of recombinant acidic and thermostable raw-starch hydrolysing α-amylase from an extreme thermophile Geobacillus thermoleovorans
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Biochemical and molecular characterization of recombinant acidic and thermostable raw-starch hydrolysing α-amylase from an extreme thermophile Geobacillus thermoleovorans
چکیده انگلیسی

A gene encoding acidic, thermostable and raw starch hydrolysing α-amylase was cloned from an extreme thermophile Geobacillus thermoleovorans and expressed. The ORF of 1650 bp encodes a 515 amino acid protein (Gt-amy) with a signal peptide of 34 amino acids at the N-terminus. Seven conserved sequences of GH-13 family have been found in its sequence. The specific enzyme activity of recombinant Gt-amy is 1723 U mg−1 protein with a molecular mass of 59 kDa. It is optimally active at pH 5.0 and 80 °C with t1/2 values of 283, 184 and 56 min at 70, 80 and 90 °C, respectively. The activation energy required for its temperature deactivation is 84.96 kJ mol−1. Ca2+ strongly inhibits Gt-amy at 10 mM concentration, and inhibition kinetics with Ca2+ reveals that inhibition occurs as a result of binding to a lower affinity secondary Ca2+ binding site in the active centre in a mixed-type inhibition manner. The Km and kcat of the Gt-amy are 0.315 mg mL−1 and 2.62 × 103 s−1, respectively. Gt-amy is Ca2+-independent at the concentration used in industrial starch saccharification, and hydrolyses raw corn and wheat starches efficiently, and thus, is applicable in starch saccharification at the industrial sub-gelatinization temperatures.

Figure optionsDownload as PowerPoint slideHighlights
► Expressed a gene encoding acidic thermostable α-amylase from G. thermoleovorans.
► This is the first ever reported Ca2+-inhibited acidic α-amylase.
► Biochemical characterization of the recombinant enzyme (Gt-amy).
► Gt-amy is Ca2+-independent at the concentration used in starch saccharification.
► Gt-amy saccharifies raw starches.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis B: Enzymatic - Volumes 85–86, January 2013, Pages 229–238
نویسندگان
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