کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8335482 1540278 2011 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
An analysis of temperature adaptation in cold active, mesophilic and thermophilic Bacillus α-amylases
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
An analysis of temperature adaptation in cold active, mesophilic and thermophilic Bacillus α-amylases
چکیده انگلیسی
A comparative biochemical and structural study was performed on a cold active α-amylase from Bacillus cereus (BCA) and two well-known homologous mesophilic and thermophilic α-amylases from Bacillus amyloliquefaciens (BAA) and Bacillus licheniformis (BLA). In spite of a high degree of sequence and structural similarity, drastic variations were found for Topt as 50, 70 and 90 °C for BCA, BAA and BLA, respectively. The half-lives of thermoinactivation were 1 and 9 min for BCA and BAA at 80 °C respectively, whilst there was no inactivation for BLA at this temperature. Thermodynamic studies on inactivation process suggested that lower thermostability of BCA is due to lower inactivation slope of the Arrhenius plots and subsequently, lower Ea and ΔH#. Increased Km and accessible surface area for catalytic residues along with a decreased number of internal interactions in this region in BCA compared to BLA suggest that BCA substrate-binding site might be temperature sensitive and is probably more flexible. On the other hand, fewer ion pairs, destructive substitutions and disruption of aromatic interaction networks in structurally critical regions of Bacillus α-amylases result in a severe decrease in BCA thermostability compared to its mesophilic and thermophilic homologues.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Biological Macromolecules - Volume 49, Issue 5, 1 December 2011, Pages 1038-1045
نویسندگان
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