Advances in biomolecular machine: methane monooxygenases

甲烷氧化菌中的甲烷单加氧酶能够在生理条件下选择性地以甲烷和氧气为底物生成甲醇,麻省理工学院的lIPPArd教授称它为“神奇的生物分子机器“。本文重点对生物分子机器甲烷单加氧酶的结构、编码基因及调控机制、催化反应机理等进行了综述,此外也简要介绍了甲烷单加氧酶的产生菌甲烷氧化菌的研究历史及分类。生物分子机器甲烷单加氧酶可催化甲烷氧化成甲醇,不仅为甲醇的生产提供了一种新颖的生产方法,而且对生物分子机器的设计也有借鉴意义。Methane monooxygenases(MMO), regarded as "an amazing biomolecular machine", catalyze the oxidation of methane to methanol under aerobic conditions.MMO catalyze the oxidation of methane elaborately, which is a novel way to catalyze methane to methanol.Furthermore, MMO can inspire the biomolecular machine design.In this review, we introduced MMO including structure, gene and catalytic mechanism.The history and the taxonomy of MMO were also introduced.国家自然科学基金(Nos.21336009;41176111;41306124); 中央高校基本科研业务费专项资金(No.2013121029)资助~

固定化双酶耦联体系制备手性胺

胺脱氢酶(amine dehydrogenase,Am DH)能够在辅酶的作用下不对称还原前手性酮制备手性胺,并与甲酸脱氢酶(formate dehydrogenase,FDH)构建耦联双酶反应体系,通过酶活检测与高效液相色谱法得出,Am DH和FDH浓度比为4∶1、底物浓度为10 mmol/L、辅酶浓度为0. 025 mmol/L时,是游离双酶耦联体系最优反应条件.为提高双酶耦联体系的稳定性,将聚乙烯亚胺-双酶复合物作为模板和催化剂,诱导钛前驱体Ti-BALDH(titanium(IV) bis-(ammoniumlactato)-dihydroxide)缩聚,形成固定化耦联体系.与游离酶体系相比,辅酶可在固定化酶体系的微环境中高效循环再生,大大提高了多酶耦联体系的催化效率

Lipase-catalyzed remote kinetic resolution of citalopram intermediate by asymmetric alcoholysis and thermodynamic analysis

Lipase-catalyzed remote resolution of the tertiary alcohol, citalopram intermediate (diol acetate), has been achieved. The chiral discrimination was obtained by the Novozym435-catalyzed alcoholysis of the primary hydroxyl ester which was four bonds away from the center. The influence of acyl acceptor structure and the organic solvents on the reaction rate and enantioselectivity were investigated. Based on the thermodynamic analysis, the difference of activation free energy between the two enantiomers which dominated the enantioselectivity was significantly affected by the organic solvents, while the acyl acceptor showed less effect. In addition, the enantiomer discrimination was driven by both the difference of activation enthalpy and activation entropy. The thermodynamic analysis provides further insights into the prediction and optimization of enantioselectivity and reaction rate in remote resolution.National Natural Science Foundation of China [20936002]; Key Project of Chinese National Programs for Fundamental Research and Development [2011CB710800]; Hi-Tech Research and Development Program of China [2011AA02A209

Metabolic evolution of Lactobacillus pentosus for lactic acid production from raw glycerol

以生物柴油产业的副产物粗甘油为底物,可降低乳酸发酵的生产成本。但是,粗甘油发酵生产乳酸存在菌体生长缓慢、菌浓较低、产酸速率和终产物浓度偏低等问题。以实验室筛选的一株戊糖乳杆菌(lACTObACIlluS PEnTOSuS r3-8)为出发菌株进行代谢进化。通过在培养基中添加高浓度的粗甘油和乳酸,分别进行菌株耐底物和产物抑制的代谢进化。用粗甘油驯化的第60代菌株,可耐受130 g·l-1的粗甘油,与出发菌株相比,生长速率提高,且生物量是原始菌株的1.23倍。用乳酸驯化的第50代菌株可耐受20 g·l-1的乳酸,生物量比初始菌株提升了18%。驯化菌株的5 l发酵罐分批发酵结果显示,以粗甘油驯化至60代的菌株的批次发酵水平相对较好,乳酸产量、甘油转化率以及生产强度分别为45.0 g·l-1、0.989 g·g-1和0.47 g·l-1·H-1。以粗甘油驯化至60代的菌株进行补料分批发酵,乳酸终浓度为83.8 g·l-1,比分批发酵提高了近1倍。High costs are the bottlenecks of traditional lactic acid fermentation process using glucose and starch as raw material.Production of lactic acid from raw glycerol, a byproduct of biodiesel, can significantly decrease the costs of fermentation.Therefore, there is a need to overcome the disadvantages of low cell growth rate, biomass of strains, as well as low productive rate and yield of lactic acid.In this work, metabolic evolution of Lactobacillus pentosus R3-8 screened by our group was carried out by adding high concentration raw glycerol and lactic acid.The 60 th generation evolved strain using raw glycerol, tolerated 130 g·L-1 raw glycerol, with 1.23 folds enhancement of biomass.The 50 th generation evolved strain using lactic acid can tolerate 20 g·L-1 lactic acid with 18% increase in biomass.The growth curves of 60 th generation evolved strain using raw glycerol cultivated in 5 L bioreactor indicated that the lactic acid concentration, yield and productivity were 45.0 g·L-1, 0.989 g·g-1and 0.47 g·L-1·h-1, respectively.Fed-batch cultivation of 60 th generation evolved strain using raw glycerol achieved 83.8 g·L-1 lactic acid, which was two folds of batch cultivation with the same strain.国家高技术研究发展计划项目(2006AA020102)~

Kinases Mst1 and Mst2 positively regulate phagocytic induction of reactive oxygen species and bactericidal activity

该研究成果揭示了吞噬性细胞内Hippo信号通路关键激酶Mst1和Mst2通过活化Rac家族蛋白来调节线粒体向吞噬小泡募集并释放ROS来清除病原体，这个生物学过程在天然免疫和宿主防御中发挥着重要作用。该成果解析了人的Mst1基因缺失或Rac2基因突变引发免疫缺陷综合症的致病机理，为研究人类感染性疾病提供了全新的视角。 该论文的主要工作由2012级博士生耿晶、2013级博士生孙秀峰以及王平、张世浩和王晓珍等学生共同承担，并与厦门市第一医院、台湾长庚大学、中国科学技术大学等单位合作完成，通讯作者为周大旺教授和陈兰芬教授。该研究工作获得了“青年千人计划”、国家自然科学基金委和科技部的资助。Mitochondria need to be juxtaposed to phagosomes for the synergistic production of ample reactive oxygen species (ROS) in phagocytes to kill pathogens. However, how phagosomes transmit signals to recruit mitochondria has remained unclear. Here we found that the kinases Mst1 and Mst2 functioned to control ROS production by regulating mitochondrial trafficking and mitochondrion-phagosome juxtaposition. Mst1 and Mst2 activated the GTPase Rac to promote Toll-like receptor (TLR)-triggered assembly of the TRAF6-ECSIT complex that is required for the recruitment of mitochondria to phagosomes. Inactive forms of Rac, including the human Rac2D57N mutant, disrupted the TRAF6-ECSIT complex by sequestering TRAF6 and substantially diminished ROS production and enhanced susceptibility to bacterial infection. Our findings demonstrate that the TLR-Mst1-Mst2-Rac signaling axis is critical for effective phagosome-mitochondrion function and bactericidal activity.Supported by the National Basic Research Program (973) of China (2015CB910502 to L.C.), China's 1000 Young Talents Program (D.Z. and L.C.), the 111 Projects (B12001 and B06016), the Fundamental Research Funds for the Central Universities of China-Xiamen University (CXB2014004 to J.Z.; 20720140551 to L.C.; and 2013121034 and 20720140537 to D.Z.), the National Natural Science Foundation of China (31270918, 81222030 and J1310027 to D.Z.; 81372617, 81422018 and U1405225 to L.C.; 81472229 to L.H.; and 81302529 to X.L.), the Natural Science Foundation of Fujian (2013J06011 to D.Z. and 2014D007 to X.L.), the US National Institutes of Health (RO1 CA136567 for J.A.) and institutional funds from Massachusetts General Hospital (for J.A.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

酸雨胁迫下稀土元素对小麦生理生化响应的作用

运用盆栽实验,对酸雨胁迫下稀土元素(REE)对小麦生理生化响应的作用进行了研究。结果表明:酸雨影响了叶绿素含量及叶绿素a/b值。叶绿素a及叶绿素总量与酸雨pH值呈正相关,POD活性随酸雨pH值减小逐渐增加,间接导致叶绿素a分解速度加快,造成叶绿素总量减少和a/b值减小,加速了叶片的老化,影响植株光能吸收、转换及碳同化。REE施用后,仍在酸雨胁迫下的植株与单一酸雨处理相比,其叶绿素含量、叶绿素a/b值、POD活性均能稳定在一定水平上。在酸雨pH>3.5的情况下REE明显地表现出对小麦体内叶绿素及过氧化物酶有一定的防护作用

酸雨胁迫下,稀土元素对菠菜膜保护系统作用

利用盆栽实验，探讨了酸雨胁迫下对菠菜膜保护酶系统的防护效应。实验结果表明：单一酸雨处理会造成超氧化物歧化酶（ Ｓ Ｏ Ｄ）、过氧化酶（ Ｃ Ａ Ｔ）活性总体水平下降，其变化曲线呈“∧”形，并使过氧化物酶（ Ｐ Ｏ Ｄ）活性明显增加。施用稀土元素后酸雨胁迫下的植株叶片中 Ｓ Ｏ Ｄ、 Ｃ Ａ Ｔ 活性总体水平上升，变化曲线的峰值向酸度较大的方向移动， Ｐ Ｏ Ｄ 活性上升幅度减小，３ 种膜保护酶的活性与单一酸雨处理组相比，处在一种相对稳定的状态下，表现出在酸度不大的情况下，稀土元素对酸雨影响菠菜膜保护系统有明显的防护作用

稀土元素对酸雨胁迫小麦活性氧清除系统响应的作用

盆栽条件下,就酸雨胁迫下小麦活性氧清除系统的响应及稀土元素作用进行了研究。结果表明:酸雨导致小麦活性氧酶促系统的SOD、CAT、POD酶活性总体水平发生变化。CAT、SOD活性减弱,POD活性增加,致使体内活性氧清除能力减弱,稀土元素的施用增加了CAT、SOD活性水平,削弱了由于酸雨胁迫所导致的POD活性的增加,从而增强了清除活性氧的能力,减弱了由于酸雨胁迫对小麦活性氧清除系统造成的影响