紫杉二烯生物合成模块与不同底盘的适配简

以酿酒酵母BY4742及其单敲菌株作为底盘细胞,优化底盘细胞甲羟戊酸途径,上调并融合表达牻牛儿基牻牛儿基焦磷酸(GGPP)合成的相关基因,引入人工合成的外源GGPP合成酶基因与紫杉二烯合成酶基因,构建了多载体紫杉二烯生物合成模块;还利用酵母组装技术,通过对紫杉二烯合成路径相关基因进行模块化设计组装,构建了依托单一着丝粒(CEN)质粒的紫杉二烯生物合成模块. 将构建的2个模块与不同底盘细胞进行适配,使紫杉二烯产量获得了数倍提升,最高产量可达74.84 mg/L.     

青蒿二烯功能模块与酵母底盘的适配性

设计构建人工酿酒酵母细胞合成青蒿二烯的关键是使外源功能模块与底盘细胞适配,本文通过对外源功能模块中的载体、蛋白表达和启动子进行优化,以提高功能模块与底盘细胞的适配性. 使用着丝粒载体和附加型载体构建了2种青蒿二烯功能模块,在过表达甲羟戊酸（MEV）途径中关键基因（截短的3-羟基-3-甲基戊二酰辅酶A还原酶基因tHMGR及法尼基焦磷酸合酶基因ERG20）的2种酵母底盘中进行适配,得到适配性较好的人工合成细胞,其产量为11.2 mg/L;将青蒿二烯合酶基因（ADS）与ERG20进行融合构建融合蛋白功能模块,在选定底盘中适配性进一步提高,青蒿二烯的产量提升至17.5 mg/L;采用不同强度的启动子（TDH3p,TEF1p和PGK1p）对融合蛋白功能模块进行调控,最终得到功能模块与底盘间适配关系更好的人工合成细胞,其产量提升到71.8 mg/L.     

稀土对红豆杉细胞中紫杉烯合成酶基因转录的影响

采用Ｎｏｒｔｈｅｒｎ Ｂｌｏｔ和高效液相色谱,对稀土作用后紫杉烯合成酶基因的转录以及紫杉醇量的变化进行分析,红豆杉细胞于对数生长期紫杉烯合成酶基因转录水平最高。（ＮＨ４）２Ｃｅ（ＮＯ３）６能有效提高紫杉烯合成酶基因的转录,并促进紫杉醇的合成。     

环二肽合酶生物合成途径研究进展

二酮哌嗪类化合物(DKPs)的特征结构是由两个α-氨基酸通过肽键缩合而成的环二肽(CDPs),稳定的六元环骨架结构使DKPs在药物化学中成为一个重要的药效团,表现出丰富的生物活性.合成可作为药物先导物的DKPs已日益引起人们的关注,其中,开展生物合成研究是拓宽其化学结构多样性的一个有效途径.与早期阐明的非核糖体肽合成酶(NRPSs)生物合成途径不同,环二肽合酶(CDPSs)以氨酰-t RNAs(aa-t RNAs)作为底物合成环二肽,其后修饰过程发生在环二肽形成之后.目前国内外已研究的经CDPS途径合成的二酮哌嗪类化合物报道了6例.对近年来环二肽合酶(CDPSs)生物合成途径相关研究进展进行了综述.     

1,3,4-噁二唑三氮烯衍生物的合成及生物活性测定

利用拼合原理,将具有生物活性的三氮烯结构与1,3,4-噁二唑结构相拼合,设计合成了11个未见报道的1,3,4-噁二唑三氮烯衍生物.所合成化合物经1H NMR,IR和HRMS得到表征.用四甲基偶氮唑盐(MTT)法法评价了该类化合物对胃癌细胞(MGC803)和前列腺癌细胞(PC-3)的抑制作用,结果显示化合物2-[4-(3,3-二甲基三氮烯-1-基)苯基]-5-(4-甲氧基苯基)-1,3,4-噁二唑(b4)、2-[4-(3,3-二甲基三氮烯-1-基)苯基]-5-(2-甲氧基苯基)-1,3,4-噁二唑(b9)、2-[4-(3,3-二甲基三氮烯-1-基)苯基]-5-(3,4-甲叉二氧基苯基)-1,3,4-噁二唑(b10)、2-[4-(3,3-二甲基三氮烯-1-基)苯基]-5-(吡啶-4-基)-1,3,4-噁二唑(b11)对前列腺癌细胞的抑制作用强于典型三氮烯药物达卡巴嗪(DTIC),其IC50值分别为74.145,87.790,87.327和104.875μmol/L,而对胃癌细胞则几乎没有抑制作用.采用微量肉汤稀释法测试了该类化合物对大肠埃希菌(E.coli.)和金黄葡萄球菌(S.aureus)的抑制作用,结果显示这类化合物对这两种细菌并没有表现出抑制作用.     

合成生物学的工业应用

利用合成生物学构建人工生命体及采用组装生物合成途径生产抗疟疾药物青蒿素的成功,引起了人们对合成生物学的极大关注.本文主要介绍合成生物学在医药、生物能源、生物基化学品及其他工业领域的应用进展概况.医药领域包括青蒿素、抗生素、合成抗体、新的治疗方法及新药开发、分析诊断试剂研究等;能源领域包括生物制氢、生物产乙醇、生物产脂肪烃、高级醇等;生物基化学品领域包括1,3-丙二醇、脂肪酸、可降解性塑料的生产等.其他领域的应用包括环境保护、环境监测、生命科学探索等.同时介绍了本课题组在构建细胞浓度控制体系、并用NADH和NADPH生物转化甘油制备1,3-丙二醇的合成生物系统、核酸适体筛选、酶的耦联体系等方面所开展的有关合成生物学研究工作.最后,分析合成生物学应用前景与风险、发展瓶颈问题,并对发展方向进行了展望,指出今后应聚焦若干重要的工业生物体系,发展合成生物学的基础理论,开发合成生物学所需要的核心工程技术,构建人工生物合成体系及相关技术体系,利用合成途径生产高附加值产品.     

选择性合成(1,3-二苯基-2-亚丁烯基)二苯甲胺席夫碱及其光催化选择性双键转移的研究

席夫碱是一类具有多功能结构的化合物.本文使用二苯甲胺和苯乙酮为原料合成了(1,3-二苯基-2-亚丁烯基)二苯甲胺席夫碱,并进行了光催化选择性双键转移的研究.结果 表明,当苯乙酮与二苯甲胺投料比为3∶1,先在135C反应4h,然后升温到165C继续反应3h,可选择性合成(1,3-二苯基-2-亚丁烯基)二苯甲胺席夫碱.该席...     

四硫富瓦烯三氮唑衍生物的合成及应用研究进展

四硫富瓦烯是一类重要的电子供体化合物,在分子导体和超分子化学领域引起广泛关注.主要介绍Cu(I)催化的叠氮和炔基的环加成反应(Cu AAC)在合成四硫富瓦烯三氮唑衍生物方面的应用进展,主要涉及含端基叠氮的四硫富瓦烯化合物和含端基炔的反应底物反应以及含端基炔的四硫富瓦烯化合物和含端基叠氮的反应底物反应两类.同时,对利用Cu AAC点击反应合成的含三氮唑功能基的四硫富瓦烯衍生物在分子识别、分子组装以及分子光电和光伏器件等光电功能材料领域的应用进展进行综述.     

有机硅反应活性中间体的研究Ⅶ: 二(α-呋喃基)硅烯与烯烃加成反应的立体化学

本文设计并合成了二(α-呋喃基)硅烯的前体,2,2-二(α-呋喃基)六甲基三硅烷(1),并研究了这种硅烯与烯烃加成的立体化学。结果表明： 二(α-呋喃基)硅烯与烯烃的加成反应是以立体专一方式进行的。其中间物硅杂环丙烷的开环反应也是以顺式方式进行的。这也说明 二(α-呋喃基)硅烯基态的电子组态是单线态。     

三叶鬼针草挥发性成分的研究

采用同时蒸馏萃取贵州三叶鬼针草不同部位挥发油，并用气相色谱-质谱进行分离测定，对比研究了它们的化学成分，共分离出69种成分，鉴定出53个化合物，主要成分为炔类、萜烯化合物及其衍生物；含量较高的化合物有(Z)-1，11-十三二烯-3，5，7，9-四炔(19．41％～37．16％)、石竹烯(15．68％～16．62％)、大牻桡牛儿烯-D(5．52％～18．50％)等。     

Yeast flotation viewed as the result of the interplay of supernatant composition and cell-wall hydrophobicity

Flotation is a process of cell separation based on the affinity of cells to air bubbles. In the present work, flotability and hydrophobicity were determined using cells from different yeasts (Hansenulla polymorpha, Saccharomyces cerevisiae, Candida albicans), which were propagated in different media and at different temperatures. Alterations to the supernatant of the cells were also carried out before the flotation assays. The results described here indicate that supernatants of the yeast cells can play a more important role on flotation than cell-wall hydrophobicity. For example, wall-hydrophobicity of strain FLT-01 of S. cerevisiae was high but flotation did not occur when their washed cells were resuspended in water. Additions of neopeptone to cultures of S. cerevisiae and H. polymorpha repressed flotation and increased the volume of foam. An additional task of the present work was to show that the relationship between cell-wall hydrophobicity and flotation performance was dependent on the method used for the measurement of hydrophobicity. Based on the assay procedure, two types of hydrophobicity were distinguished: (a) the apparent hydrophobicity for cells suspended in the medium and expressed by the degree of cell affinity to the organic solvent in the two-phase system supernatant/hexane; (b) the standard hydrophobicity, which was determined for cells suspended in a standard solution (acetate buffer, in the present work) within the acetate buffer/hexane system. Flotation of cells of S. cerevisiae and C. albicans were best related to the degree of apparent hydrophobicity (varying with the supernatant composition at the cell/medium interface) rather than to the degree of standard hydrophobicity (varying with the alterations in the wall components, since the liquid phase was constant in the assay). However, depending on the yeast unpredictable results can be obtained. For example, cells of H. polymorpha exhibited good flotation associated to a high degree of standard hydrophobicity while having a lower degree of apparent hydrophobicity. Concerning growth temperature, flotation of cells of C. albicans was strongly repressed when the temperature was raised from 30 to 38 °C while a similar effect was not observed in cultures of S. cerevisiae and H. polymorpha. It is difficult to understand and predict flotation of yeast cells but simple modifications made to the supernatant of cultures can activate or repress flotation.     

Calorimetric study on the effect of Co γ-rays on the growth of microorganisms

Using a calorimeter equipped with 24 sample units, the heat evolution from growing Saccharomyces cerevisiae, Escherichia coli and spores of Bacillus pumilus and Bacillus stearothermophilus was detected in the form of growth thermograms. Irradiation with ⁶⁰Co γ-rays affected the growth pattern, which was used for a quantitative analysis of the effect on microorganisms. Irradiation of B. pumilus and B. stearothermophilus spores led to dose-dependent delays in growth, indicating a bactericidal effect. In case of ⁶⁰Co γ-irradiated S. cerevisiae, a dose-dependent reduction of the growth rate constant was observed together with the retardation in growth, indicating a combination of bactericidal and bacteriostatic effects. An equation to determine the number of survivors on the basis of the retardation in growth t and the growth rate constant μ was developed, which proved the opportunity to use the calorimetric technique in predictive microbiology.     

基于标记法的福白菊精油抗真菌机理研究

以福白菊为原料, 通过有机溶剂萃取和水蒸气蒸馏相结合制备福白菊精油. 分别采用健那绿、 细胞膜荧光探针DiI、 碘化丙啶、 罗丹明123以及溴化乙锭等染料标记酵母细胞、 酵母细胞膜、 酵母线粒体和质粒DNA, 研究福白菊精油对酵母细胞、 酵母细胞膜、 线粒体以及质粒DNA的破坏作用, 探讨福白菊精油的抗真菌机理. 研究结果表明, 福白菊精油不仅能破坏真菌的细胞膜, 使其细胞内含物外泄, 还能够穿过细胞膜, 破坏其线粒体膜和DNA, 最终导致真菌细胞死亡.     

The early stages of Saccharomyces cerevisiae yeast suspensions damage in moderate pulsed electric fields

The objectives of this study were to investigate the effects of pulsed electric fields (PEF) application to colloidal suspension of Saccharomyces cerevisiae. The electrical conductivity measurements during the PEF-treatment of S. cerevisiae suspensions were used to monitor the extent of cell damages in the intervals of electric field strength E = 3–15 kV/cm and time of PEF treatment t_PEF = 10⁻⁴ to 1 s. At relatively small fields (E < 7.5 kV/cm) the early stages of yeast cells damages were observed. At such treatment conditions, the damage was incomplete and developed at long time of PEF treatment, below the value of E = 7.5 kV/cm which is commonly referred in literature as a threshold for this culture. Data obtained for the disintegration in conductivity experiments were found in good correlation with direct counting of yeast lethality using light microscopy. The PEF-induced lethality of the yeast cells and size flocs increased with the mixing of suspensions and the increase of temperature.     

阿舒假囊酵母合成的精油及其抗真菌活性与机理

利用发酵法对阿舒假囊酵母进行发酵, 用萃取法和水蒸气蒸馏法从发酵液中提取精油; 通过气相色谱-质谱(GC-MS)法确定其成分; 分别利用抑菌圈和二倍稀释法实验法测定了精油的抗真菌能力、 最小抑菌浓度和最小杀菌浓度; 利用荧光标记法、 精油处理酵母后细胞内容物检测法及透射电子显微镜研究了精油的抗菌机理. 结果表明, 阿舒假囊酵母发酵法得到的精油产率为0.54 g/L. 用GC-MS法鉴定了22种化学成分, 占精油总量的98.82%. 精油主要由单萜、 倍半萜、 芳香醇和倍半萜烃类物质组成. 精油对白色念珠菌、 光滑念珠菌、 热带念珠菌、 季也蒙念珠菌、 新型隐球菌和酿酒酵母具有良好的抗菌活性, 其最小抑菌浓度分别为31.25, 31.25, 62.5, 31.25, 15.625和15.625 μg/mL; 最小杀菌浓度分别为62.5, 62.5, 125.0, 62.5, 31.25和31.25 μg/mL. 结果表明, 精油的抗菌机理可能是破坏真菌的细胞壁、 细胞膜, 使胞内物质外泄, 最终导致真菌死亡. 该研究结果为发酵法合成精油及其应用提供了新思路.     

Studies on taxadiene synthase: interception of the cyclization cascade at the verticillene stage and rearrangement to phomactatriene

The cyclization of geranylgeranyl diphosphate (GGDP) to taxadiene catalyzed by taxadiene synthase has been suggested to proceed in stages, involving a transient bicyclic verticillyl carbocation intermediate, which also has been proposed in the biosynthetic pathway leading to phomactatriene by marine fungi of Phoma sp. On incubation with des-7-methylGGDP, which would be expected to decrease the stability of a carbocation produced by hydride migration, taxadiene synthase produced phomactatrienes as major products. This indicates that the verticillyl carbocation was indeed formed but underwent further skeletal rearrangements, diverging from the usual pathway taken by GGDP en route to taxadiene. Products were identified using GC-MS, one- and two-dimensional NMR, and X-ray crystallography.     

生物-化学法合成黑色素前体5, 6-二羟基吲哚

研究了偶联Saccharomyces cerevisiae BY4741/pYX212?TYR催化L-多巴(L-Dopa)合成多巴色素(DC)的生物氧化步骤和DC还原合成5,6-二羟基吲哚(DHI)化学步骤, 实现了DHI的生物-化学合成. 通过优化生物氧化步骤的反应条件及供氧策略等因素, 使L-Dopa的转化率提升至94.75%; 通过优化化学还原步骤反应条件及化学助剂, 使DHI的产率提高到90.03%. 产物的超高效液相色谱-四极杆飞行时间质谱联用(UPLC-Q-TOF-MS)分析结果表明, 反应体系中存在DHI可溶性低聚物.     

Chiral Non-racemic Bis(vicinal 1,2-Diamines): 4,5-Diamino-N-(3,4-diaminobutyl)pentanamide Tetrahydrochloride, N,N′-Bis[3,4-bis (t-butoxycarbonylamino)butyl]urea and N,N′Bis

The reaction of (R) or (S)-N⁴,N⁵-bis(t-butoxycarbonyl)-4,5-diaminopentanoic acid (6) with (R) or (S)-N³,N⁴-bis(t-butoxycarbonyl)-3,4-diaminobutylisocyanate (8) catalyzed by 4-dimethylamino pyridine (DMAP), leads to the synthesis of (R,R), (S,S), (R,S) and (S,R) isomeric amides (11 a — d) The addition of adipic acid monomethyl ester to (R) or (S) isocyanate, followed by saponification, acidification and subsequent reaction with the second molecule of (R) or (S) isocyanate allows isolation of the (R,R), (S.S) and the meso isomers of N,N′-bis[3,4-bis(t-butoxycarbonylamino) butyl]hexanediamide (17) Removal of protecting groups with HCl/EtOH affords chiral non-racemic molecules having two free vicinal diamine units.