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新型耐热β-1,4-木糖苷酶的重组表达及酶学性质 被引量:4
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作者 黄颖 姚雪妍 +3 位作者 刘腾飞 米硕甫 孙丽超 辛凤姣 《微生物学报》 CAS CSCD 北大核心 2019年第4期689-699,共11页
【目的】拟对来源于热解纤维素果汁杆菌的新型β-木糖苷酶基因(CoXyl B)进行重组表达和酶学性质研究。【方法】在大肠杆菌系统中成功表达CoXyl B基因,并通过镍柱亲和层析、强阴离子交换和凝胶层析等纯化方法获得纯酶。【结果】对CoXyl ... 【目的】拟对来源于热解纤维素果汁杆菌的新型β-木糖苷酶基因(CoXyl B)进行重组表达和酶学性质研究。【方法】在大肠杆菌系统中成功表达CoXyl B基因,并通过镍柱亲和层析、强阴离子交换和凝胶层析等纯化方法获得纯酶。【结果】对CoXyl B酶学性质的研究结果显示,在以4-对硝基苯酚-β-D-木糖苷为底物时,该酶的最适反应温度为90℃,最适反应pH为6.0。在40–70℃范围内CoXyl B酶活较高且比较稳定。在pH 5.0–6.0之间,70℃孵育1 h后,CoXyl B的相对酶活仍保留80%以上。Ag^+、高浓度的SDS和PMSF对酶活力的抑制作用较显著,而高浓度Mg^(2+)、Li^+和EDTA对酶活力的激活作用较为明显。CoXyl B的k_(cat)和K_m值分别为5.0×10^(–3)s^(–1)和1.9 mmol/L。薄层层析色谱显示CoXyl B具有降解木二糖、木三糖和木四糖的能力。【结论】本研究鉴定出CoXyl B为一种新型的极端耐热木糖苷酶,CoXyl B的酶学性质研究将为其在食品热加工以及生物降解领域中的应用提供参考。 展开更多
关键词 热解纤维素果汁杆菌属 极端耐热 Β-木糖苷酶 重组表达 酶学性质
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Interaction of Hsp40 with influenza virus M2 protein: implications for PKR signaling pathway 被引量:13
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作者 Zhenhong Guan Di Liu +5 位作者 shuofu mi Jie Zhang Qinong Ye ming Wang George F.Gao Jinghua Yan 《Protein & Cell》 SCIE CSCD 2010年第10期944-955,共12页
Influenza virus contains three integral membrane proteins:haemagglutinin,neuraminidase,and matrix protein(M1 and M2).Among them,M2 protein functions as an ion channel,important for virus uncoating in endosomes of viru... Influenza virus contains three integral membrane proteins:haemagglutinin,neuraminidase,and matrix protein(M1 and M2).Among them,M2 protein functions as an ion channel,important for virus uncoating in endosomes of virus-infected cells and essential for virus replication.In an effort to explore potential new functions of M2 in the virus life cycle,we used yeast two-hybrid system to search for M2-associated cellular proteins.One of the positive clones was identified as human Hsp40/Hdj1,a DnaJ/Hsp40 family protein.Here,we report that both BM2(M2 of influenza B virus)and A/M2(M2 of influenza A virus)interacted with Hsp40 in vitro and in vivo.The region of M2-Hsp40 interaction has been mapped to the CTD1 domain of Hsp40.Hsp40 has been reported to be a regulator of PKR signaling pathway by interacting with p58^(IPK) that is a cellular inhibitor of PKR.PKR is a crucial component of the host defense response against virus infection.We therefore attempted to understand the relationship among M2,Hsp40 and p58^(IPK) by further experimentation.The results demonstrated that both A/M2 and BM2 are able to bind to p58^(IPK)in vitro and in vivo and enhance PKR autophosphorylation probably via forming a stable complex with Hsp40 and P58^(IPK),and consequently induce cell death.These results suggest that influenza virus M2 protein is involved in p58^(IPK)mediated PKR regulation during influenza virus infection,therefore affecting infected-cell life cycle and virus replication. 展开更多
关键词 M2 protein of influenza virus Hsp40 P58^(IPK) protein interaction PKR signal pathway
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