Research Progress of α-Glucuronidase, an Enzyme for Degrading Hemicellulose Side-Chain

半纤维素是自然界中最丰富的可再生资源之一,将半纤维素降解为单糖并转化为燃料或化学品一直是科学界研究的热点。半纤维素是由木糖基主链以及α-葡萄糖醛酸等侧链共同组成的异质多聚体。α-葡萄糖醛酸酶是半纤维素完全降解过程中的关键酶之一,能够水解4-O-甲基葡萄糖醛酸与木糖之间的α-1,2-糖苷键。本文综述了α-葡萄糖醛酸酶的分类、催化机制及晶体结构、酶学性质和基因克隆表达等方面的研究进展,同时对该研究进行了展望。Hemicellulose is one of the most abundant renewable resources in nature.The bioconversion of hemicellulose into biofuels or chemicals is a research hotspot in the world.Hemicellulose consists of a backbone of xylan residues and some branches like glucuronic acid.α-Glucuronidase, which is capable to hydrolysis the α-1,2-glycosidic bond between xylan and glucuronic acid, is one of the key enzyme to degrade hemicellulose completely.The recent research progresses on catalysis mechanism, structure, charaterization, and gene cloning of α-glucuronidase are summarized in this paper.国家自然科学基金(31170067;21303142); 国家重点基础研究发展计划(973计划;2010CB732201); 福建省自然科学基金(2012J05029); 农业部“引进国际先进农业科学技术”项目(2013-Z70

Cloning and heterologous expression of a novel GH10 xylanase gene from Hypocrea orientalis EU7-22

木聚糖酶是降解半纤维素最主要的酶,对于开发可再生生物能源具有重要的应用价值。分别以东方肉座菌(HyPOCrEA OrIEnTAlIS)Eu7-22的基因组dnA和C dnA为模板,利用染色体步移和PCr技术首次克隆获得该菌gH10家族木聚糖酶Ⅲ的基因(XynⅢ),并对其进行生物信息学分析。结果表明:该基因全长1283 bP(gXynⅢ),含有3个内含子;CdS序列为1044 bP(CXynⅢ),编码347个氨基酸,n端含有一个16 AA的信号肽序列;XynⅢ氨基酸序列与TrICHOdErMA PSEudOkOnIngII的EndOXylAnASE具有较高的同源性。经生物信息学分析,XynⅢ成熟蛋白可能含有18个n-糖基化位点,其理论等电点(P I)为6.14,蛋白质分子质量为36.55 ku,属于亲水性蛋白;SWISS-MOdEl建模预测,XynⅢ成熟蛋白中含有11个α螺旋,其核心结构为8个β折叠片围成一个柱状结构。同时将编码成熟蛋白的基因片段MXynⅢ与P PIC9k质粒连接构建表达载体后转化毕赤酵母,对重组子表达产物进行酶活检测显示该基因能在毕赤酵母中表达有生物活性的XynⅢ并分泌到胞外,发酵液中的木聚糖酶活在诱导培养168 H后可达到127.5 Iu/M l。Endo-1,4-xylanase( E.C.3.2.1.8) is the major enzyme to the conversion of hemicelluloses into xylo-oligosaccharide.In this research,a novel GH10 xylanase Ⅲ( xyn Ⅲ) gene was cloned from Hypocrea orientalis EU7-22 by chromosome walking and PCR.The results showed that the DNA fragment( 1283 bp) encoding xynⅢ( gxynⅢ) contained three introns.The CDS of xynⅢ( cxynⅢ) encoded 331 amino acids of putative mature protein and a 16 aa signal in N terminator.The amino acid sequence of xynⅢ is highly homologous with the endoxylanase of Trichoderma pseudokoningii.The bioinformatics analysis showed that the theoretical isoelectric point and the molecular weight of putative mature protein of XYNⅢ were 6.14 and 36.55 ku,respectively.It is a soluble hydrophilic protein containing 18 N-glycosylation sites.The 3D structure predicted with SWISS-Model showed that XYNⅢ protein contained11 alpha helices and 8 extended strands.A recombinant plasmid p PIC9K-xynⅢ was constructed and then transformed into Pichia pastoris.The transformant identified by PCR was induced to produce XYNⅢ enzyme with 1% methanol.And after 168 hours induced expression,the produced crude enzyme was detected to reach a high enzymatic activity of 127.5 IU / m L.国家自然科学基金(21303142;31170067); 福建省海洋高新产业发展专项项目(闽海洋高新[2014]25号); 厦门市海洋经济发展专项资金项目(14GZP59HJ29

水解法提取纯化刺槐素的工艺研究

目的优选野菊花中刺槐苷的水解工艺。方法采用均匀设计法,以高效液相色谱法(HPLC)测定野菊花中刺槐素含量,探讨影响刺槐素提取效率的因素,并筛选出最佳提取条件。结果最佳水解工艺为盐酸与药液比为5∶2,盐酸浓度3 mol/L,水解时间为3 h,水解温度为100℃。结论 HPLC法测定野菊花中刺槐素含量的方法,快速、可行。均匀设计法优选的野菊花中刺槐素提取工艺,操作简单,节约时间,提取率比原工艺有明显提高

液相色谱-串联质谱法研究白花前胡甲素脂质体在大鼠体内的药动学

目的制备白花前胡甲素脂质体并进一步研究其在大鼠体内的药动学。方法采用乙醇注入法制备白花前胡甲素脂质体,采用正交设计优化处方。白花前胡甲素脂质体按5、10、20mg·kg~(-1)低、中、高3个剂量经大鼠颈静脉给药后检测一定时间点的血药浓度,对照组为10mg·kg~(-1)的白花前胡甲素溶液。结果制备的脂质体含药量为2g·L~(-1),包封率为93.2%,脂质体高、中、低剂量组及对照组的t_(1/2)分别为(136.58±22.86),(74.12±6.97),(44.93±7.47),(51.26±5.13)min;AUC_(0-∞)分别为(215.93±33.24),(91.75±26.47),(29.22±4.47),(66.90±14.54)min·mg·L~(-1)。结论成功制备了白花前胡甲素脂质体,制得的白花前胡甲素脂质体在大鼠体内半衰期显著延长,生物利用度有明显的提高

三工河流域琵琶柴群落凋落物对土壤有机碳固定的影响

土壤有机碳是土壤碳库的重要组成部分,对生态系统生产力和全球碳循环有着重要作用。采用凋落物收集器和DIRT法(添加和去除凋落物法)研究三工河流域两处不同琵琶柴群落凋落物的产量、现存量、凋落物处理对土壤有机碳的影响。结果表明:群落1和群落2的凋落物产量季节变化趋势相同,均呈"N"型变化,在10月份达到最大值,7月或8月份达到次大值。凋落物现存量随季节均呈现"W"型变化,在10月份达到最大值,最大值分别为30.65 g/m~2和57.87 g/m~2。土壤有机碳随土壤深度的增加均逐渐降低,群落1和群落2分别下降了61.73%—62.39%和18.24%—25.84%。与对照处理相比,去除凋落物处理(NL)的群落1和群落2土壤有机碳分别降低了6.97%和18.38%;添加凋落物处理(DL)的土壤有机碳分别增加了19.64%和13.66%;去除凋落物处理(NL)的群落1和群落2土壤有机碳储量分别为1007.36 kg/hm~2和709.30 kg/hm~2,添加凋落物处理(DL)的土壤有机碳储量分别为1197.88 kg/hm~2和1010.78 kg/hm~2。双因素方差分析表明群落1的土层深度和三种处理对土壤有机碳的交互作用不显著,群落2的交互作用显著。回归分析显示:土壤水分、电导率、pH、容重和温度是导致两琵琶柴群落土壤有机碳不同的主要生态因子。相对较高的土壤pH和盐分含量抑制了凋落物的分解,导致凋落物现存量较高、土壤有机碳含量低;相对较高的土壤含水量和较小的容重,有利于土壤生物的活性和土壤有机碳的矿化,导致土壤有机碳含量降低

Aripiprazole versus other atypical antipsychotics for schizophrenia

BACKGROUND: In most western industrialised countries, second generation (atypical) antipsychotics are recommended as first line drug treatments for people with schizophrenia. In this review we specifically examine how the efficacy and tolerability of one such agent - aripiprazole - differs from that of other comparable second generation antipsychotics. OBJECTIVES: To evaluate the effects of aripiprazole compared with other atypical antipsychotics for people with schizophrenia and schizophrenia-like psychoses. SEARCH METHODS: We searched the Cochrane Schizophrenia Group Trials Register (November 2011), inspected references of all identified studies for further trials, and contacted relevant pharmaceutical companies, drug approval agencies and authors of trials for additional information. SELECTION CRITERIA: We included all randomised clinical trials (RCTs) comparing aripiprazole (oral) with oral and parenteral forms of amisulpride, clozapine, olanzapine, quetiapine, risperidone, sertindole, ziprasidone or zotepine for people with schizophrenia or schizophrenia-like psychoses. DATA COLLECTION AND ANALYSIS: We extracted data independently. For dichotomous data we calculated risk ratios (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. Where possible, we calculated illustrative comparative risks for primary outcomes. For continuous data, we calculated mean differences (MD), again based on a random-effects model. We assessed risk of bias for each included study. MAIN RESULTS: We included 12 trials involving 6389 patients. Aripiprazole was compared to olanzapine, risperidone and ziprasidone. All trials were sponsored by an interested drug manufacturer. The overall number of participants leaving studies early was 30% to 40%, limiting validity (no differences between groups).When compared with olanzapine no differences were apparent for global state (no clinically important change: n = 703, 1 RCT, RR short-term 1.00 95% CI 0.81 to 1.22; n = 317, 1 RCT, RR medium-term 1.08 95% CI 0.95 to 1.22) but mental state tended to favour olanzapine (n = 1360, 3 RCTs, MD total Positive and Negative Syndrome Scale (PANSS) 4.68 95% CI 2.21 to 7.16). There was no significant difference in extrapyramidal symptoms (n = 529, 2 RCTs, RR 0.99 95% CI 0.62 to 1.59) but fewer in the aripiprazole group had increased cholesterol levels (n = 223, 1 RCT, RR 0.32 95% CI 0.19 to 0.54) or weight gain of 7% or more of total body weight (n = 1095, 3 RCTs, RR 0.39 95% CI 0.28 to 0.54).When compared with risperidone, aripiprazole showed no advantage in terms of global state (n = 384, 2 RCTs, RR no important improvement 1.14 95% CI 0.81 to 1.60) or mental state (n = 372, 2 RCTs, MD total PANSS 1.50 95% CI -2.96 to 5.96).One study compared aripiprazole with ziprasidone (n = 247) and both the groups reported similar change in the global state (n = 247, 1 RCT, MD average change in Clinical Global Impression-Severity (CGI-S) score -0.03 95% CI -0.28 to 0.22) and mental state (n = 247, 1 RCT, MD change PANSS -3.00 95% CI -7.29 to 1.29).When compared with any one of several new generation antipsychotic drugs the aripiprazole group showed improvement in global state in energy (n = 523, 1 RCT, RR 0.69 95% CI 0.56 to 0.84), mood (n = 523, 1 RCT, RR 0.77 95% CI 0.65 to 0.92), negative symptoms (n = 523, 1 RCT, RR 0.82 95% CI 0.68 to 0.99), somnolence (n = 523, 1 RCT, RR 0.80 95% CI 0.69 to 0.93) and weight gain (n = 523, 1 RCT, RR 0.84 95% CI 0.76 to 0.94). Significantly more people given aripiprazole reported symptoms of nausea (n = 2881, 3 RCTs, RR 3.13 95% CI 2.12 to 4.61) but weight gain (7% or more of total body weight) was less common in people allocated aripiprazole (n = 330, 1 RCT, RR 0.35 95% CI 0.19 to 0.64). Aripiprazole may have value in aggression but data are limited. This will be the focus of another review. AUTHORS' CONCLUSIONS: Information on all comparisons are of limited quality, are incomplete and problematic to apply clinically. Aripiprazole is an antipsychotic drug with a variant but not absent adverse effect profile. Long-term data are sparse and there is considerable scope for another update of this review as new data emerges from the many Chinese studies as well as from ongoing larger, independent pragmatic trials