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该研究以凝结芽孢杆菌(Bacillus coagulans)IPE22为研究对象,通过聚合酶链式反应(PCR)扩增获得木酮糖激酶基因Bc-XK,将其与载体pET-30a连接后,在大肠杆菌(Escherichia coli)BL21(DE3)中进行诱导表达。然后采用镍柱亲和层析纯化重组酶Bc-XK,对基因Bc-XK及其编码的蛋白质进行生信分析。结果表明,纯化后重组酶Bc-XK的酶比活力为(20.56±3.31) U/mg,热稳定性好,在60 ℃保持活力180 min以上,具有很好的工业应用潜力。Bc-XK基因含有一个1 536 bp的开放阅读框,共编码511个氨基酸,其编码的蛋白质为亲水蛋白,等电点(PI)为5.46,分子质量为56.15 kDa,二级结构中α-螺旋、无规卷曲和延伸链含量丰富,3个催化位点分别为天冬氨酸-8、苏氨酸-11、天冬氨酸-239,高度保守。 相似文献
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Margareth Andrea Patiño Juan Pablo Ortiz Mario Velásquez Boris U. Stambuk 《Yeast (Chichester, England)》2019,36(9):541-556
Xylose is the second most abundant sugar in nature. Its efficient fermentation has been considered as a critical factor for a feasible conversion of renewable biomass resources into biofuels and other chemicals. The yeast Saccharomyces cerevisiae is of exceptional industrial importance due to its excellent capability to ferment sugars. However, although S. cerevisiae is able to ferment xylulose, it is considered unable to metabolize xylose, and thus, a lot of research has been directed to engineer this yeast with heterologous genes to allow xylose consumption and fermentation. The analysis of the natural genetic diversity of this yeast has also revealed some nonrecombinant S. cerevisiae strains that consume or even grow (modestly) on xylose. The genome of this yeast has all the genes required for xylose transport and metabolism through the xylose reductase, xylitol dehydrogenase, and xylulokinase pathway, but there seems to be problems in their kinetic properties and/or required expression. Self-cloning industrial S. cerevisiae strains overexpressing some of the endogenous genes have shown interesting results, and new strategies and approaches designed to improve these S. cerevisiae strains for ethanol production from xylose will also be presented in this review. 相似文献
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Urs Schuricht Kirsten Endler Lothar Hennig Matthias Findeisen Peter Welzel 《Advanced Synthesis \u0026amp; Catalysis》2000,342(8):761-772
Feeding experiments ( 13C and 15N‐labeled precursors) shed light on the biosynthetic origin of the chromophore (unit A of 1 ), the N‐acetyl groups, the 4‐C‐methyl group of the moenuronamide unit (part F of 1 ), the sugar units, and the lipid part (unit I of 1 ) of the antibiotic moenomycin A( 1 ). The lipid part is completely isoprenoid and is constructed via the non‐mevalonate pathway. The central C 10 part originates from a precursor like geranyl or linalyl diphosphate and is formed by a route involving ring formation between C‐2 and C‐6 of the monoterpene unit, two successive rearrangements to give a 7‐membered ring intermediate and cleavage of the ring between C‐5 and C‐11 (moenocinol numbering). 相似文献
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通过RT-PCR方法克隆得到Candida tropicalis木糖醇脱氢酶基因xyl2,将该基因连入酵母表达载体pYES2的诱导型启动子GAL1下,构建表达质粒pYES2-xyl2;同时用从Pichia pastoris中克隆获取的甘油醛磷酸脱氢酶基因GAP换下GAL1基因,构建含组成型启动子GAP基因的表达质粒pYES2-GAP-xyl2;通过电转化法将其依次转入酿酒酵母S.cerevisiae INVSc1,山梨醇培养基上筛选的转化子经木糖醇梯度驯化培养,筛选出1株耐木糖醇浓度为20%的酿酒酵母重组菌株ZCX4和1株在半乳糖诱导下耐木糖醇浓度为15%的重组菌株YDX2。酶活测定表明,重组菌株ZCX4比酶活0.621 U/mg(蛋白),是YDX2比酶活的2.29倍。摇瓶发酵结果显示,重组菌株ZCX4木糖醇消耗76.46 g/L,木糖醇消耗率为76.46%,是重组菌株YDX2木糖醇消耗率的1.63倍,说明木糖醇脱氢酶实现了高效表达。 相似文献
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