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Promoter recognition by sigma-37 RNA polymerase from Bacillus subtilis 总被引:21,自引:0,他引:21
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Jin-Ha Kim Ponnandy Prabhu Marimuthu Jeya Manish Kumar Tiwari Hee-Jung Moon Raushan Kumar Singh Jung-Kul Lee 《Applied microbiology and biotechnology》2010,85(6):1839-1847
An isolated gene from Bacillus subtilis str. 168 encoding a putative isomerase was proposed as an L-arabinose isomerase (L-AI), cloned into Escherichia coli, and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1,491 bp, capable of
encoding a polypeptide of 496 amino acid residues. The gene was overexpressed in E. coli and the protein was purified using nickel-nitrilotriacetic acid chromatography. The purified enzyme showed the highest catalytic
efficiency ever reported, with a k
cat of 14,504 min−1 and a k
cat/K
m of 121 min−1 mM−1 for L-arabinose. A homology model of B. subtilis L-AI was constructed based on the X-ray crystal structure of E. coli
L-AI. Molecular dynamics simulation studies of the enzyme with the natural substrate, L-arabinose, and an analogue, D-galactose, shed light on the unique substrate specificity displayed by B. subtilis
L-AI only towards L-arabinose. Although L-AIs have been characterized from several other sources, B. subtilis
L-AI is distinguished from other L-AIs by its high substrate specificity and catalytic efficiency for L-arabinose. 相似文献
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RNA polymerase from Bacillus amyloliquefaciens 总被引:3,自引:0,他引:3
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b-丙氨酸是一种重要的医药化工原料,目前主要依靠化学法进行生产。探寻更为环保和高效的生物生产法是未来研究的一个方向。L-天冬氨酸a脱羧酶 (PanD) 能特异地脱去L-天冬氨酸的a羧基,生成b-丙氨酸。本文比较了3种分别来源于大肠杆菌、谷氨酸棒状杆菌及枯草芽胞杆菌的PanD比酶活 (分别为0.98、7.52和8.4 U/mg)。后两者的最适pH均为6.5,最适反应温度分别为65 ℃及60 ℃。与目前研究最多的来源于大肠杆菌和谷氨酸棒状杆菌的PanD相比,来源于枯草芽胞杆菌的PanD具有更好的活性和热稳定性,具有更强的工业应用潜力。同时,本文对该酶特有的翻译后自剪切及机理性失活现象进行了分析和讨论。 相似文献