• 【末端糖基转移酶对糖蛋白受体的差异识别。】 复制标题 收藏 收藏
    DOI:10.1093/glycob/7.2.241 复制DOI
    作者列表:Yeh J,Cummings RD
    BACKGROUND & AIMS: The factors regulating modifications of terminal beta-Gal residues in lactosaminyl (Gal beta 1-->4GlcNAc beta-->R) units in intact glycoproteins are not well understood. To examine these factors, rat liver alpha 2,3 sialyltransferase (alpha 2,3ST) and alpha 2,6 sialyltransferase (alpha 2,6ST) and the murine alpha 1,3 galactosyltransferase (alpha 1,3GT) were incubated with a variety of well-defined desialylated glycoproteins and with glycoproteins in extracts of the Lec2 mutant CHO cells. Lec2 cells constitutively synthesize nonsialylated glycoproteins with terminal lactosaminyl sequences. The results demonstrate that each enzyme displays preferences for glycoprotein acceptors and in the types of N-glycans recognized. The alpha 2,3ST, in contrast to the alpha 2,6ST and alpha 1,3GT, prefers more branched N-glycans compared to diantennary N-glycans. However, only the alpha 1,3GT is able to efficiently modify polylactosamines (3Gal beta 1-->4GlcNAc beta 1-->)n in N-glycans. Glycopeptides were also prepared by proteolysis of Lec2 glycoproteins and tested as acceptors compared to intact Lec2 glycoproteins. The alpha 2,6ST and alpha 1,3GT utilized intact glycoproteins and glycopeptides with a 2-fold preference for the former over the latter. In contrast, the alpha 2,3ST showed a 20-fold preference for intact glycoproteins over glycopeptides. These results demonstrate that each of these terminal glycosyltransferases differentially recognizes glycans and glycoprotein acceptors, and that the alpha 2,3ST requires peptide features for efficient utilization of branched N-glycan acceptors.

    背景与目标: 调节完整糖蛋白中乳糖胺基 (Gal beta 1->4GlcNAc beta->R) 单元末端 β-Gal残基修饰的因素尚不清楚。为了检查这些因素,大鼠肝脏 α 2,3唾液酸转移酶 (α2,3ST) 和 α 2,6唾液酸转移酶 (α2,6ST) 和鼠 α 1,3半乳糖基转移酶 (α1,3GT) 与各种定义明确的去唾液酸化糖蛋白和lel2突变CHO细胞提取物中的糖蛋白一起孵育。Leco2细胞组成型合成具有末端乳糖胺基序列的非唾液酸化糖蛋白。结果表明,每种酶都显示出对糖蛋白受体和识别的N-聚糖类型的偏好。与二触角N-聚糖相比,α2,3ST和 α2,6ST和 α1,3GT更喜欢支链N-聚糖。然而,只有 α1,3GT能够有效地修饰n-聚糖中的聚乳糖胺 (3Gal β1->4 glcnacβ1->) N。还通过lec 2糖蛋白的蛋白水解制备了糖肽,并与完整的lec 2糖蛋白相比作为受体进行了测试。Α2、6ST和 α1、3GT使用完整的糖蛋白和糖肽,前者比后者偏好2倍。相反,α2,3ST对完整糖蛋白的偏好是糖肽的20倍。这些结果表明,这些末端糖基转移酶中的每一个都有差异地识别聚糖和糖蛋白受体,并且 α2,3ST需要肽特征才能有效利用支链N-聚糖受体。
  • 【密度泛函理论过渡态模型,用于预测1,4 Michael受体的Ames致突变性。】 复制标题 收藏 收藏
    DOI:10.1021/acs.jcim.9b00966 复制DOI
    作者列表:Townsend PA,Grayson MN
    BACKGROUND & AIMS: :Assessing the safety of new chemicals, without introducing the need for animal testing, is a task of great importance. The Ames test, a widely used bioassay to assess mutagenicity, can be an expensive, wasteful process with animal-derived reagents. Existing in silico methods for the prediction of Ames test results are traditionally based on chemical category formation and can lead to false positive predictions. Category formation also neglects the intrinsic chemistry associated with DNA reactivity. Activation energies and HOMO/LUMO energies for thirty 1,4 Michael acceptors were calculated using a model nucleobase and were further used to predict the Ames test result of these compounds. The proposed model builds upon existing work and examines the fundamental toxicant-target interactions using density functional theory transition-state modeling. The results show that Michael acceptors with activation energies <20.7 kcal/mol and LUMO energies < -1.85 eV are likely to act as direct mutagens upon exposure to DNA.
    背景与目标: : 在不需要进行动物测试的情况下评估新化学品的安全性是一项非常重要的任务。Ames测试是一种广泛用于评估诱变性的生物测定法,使用动物衍生试剂可能是一个昂贵,浪费的过程。现有的用于预测Ames测试结果的计算机方法传统上是基于化学类别的形成,并且可能导致假阳性预测。类别形成也忽略了与DNA反应性相关的内在化学。使用模型核碱基计算三十个1,4 Michael受体的活化能和HOMO/LUMO能量,并进一步用于预测这些化合物的Ames测试结果。所提出的模型建立在现有工作的基础上,并使用密度泛函理论过渡态模型研究了基本的毒物-目标相互作用。结果表明,活化能 <20.7 kcal/mol和LUMO能量 <-1.85 eV的Michael受体在暴露于DNA时可能充当直接诱变剂。
  • 【金属离子和氢键受体在nitro-9[(烷基氨基) 氨基]-吖啶药物互变异构平衡中的作用。】 复制标题 收藏 收藏
    DOI:10.1155/S156536330400007X 复制DOI
    作者列表:Carlone M,Di Masi NG,Maresca L,Margiotta N,Natile G
    BACKGROUND & AIMS: :3-nitro-9-[2-(dialkylamino)ethyl)]aminoacridines (alkyl = methyl or ethyl) have been used as ligands towards platinum(If). The end product is a complex in which the acridine acts as a tridentate ligand contributing the two exocyclic nitrogen atoms and one of the two peri carbons. The metallation takes place predominantly at the peri position of the unsubstituted ring. The coordinated acridine is in the imino tautomeric form although, in the free state, it occurs exclusively in the amino form (both in the solid state and in solution). The imino tautomer is considered to be the biologically active form. In the platinated species the N(10)H of the acridine can be involved in strong hydrogen bonding with a chloride ion leading to formation of an association complex, the formation constant has been found to be 1.4+/-10(3) M(-1). The N(10)H...CI interaction can influence the tautomeric equilibrium of the acridine dye also in the uncoordinated species, however, the shift in favor of the imino tautomer is not complete.
    背景与目标: : 3-硝基-9-[2-(二烷基氨基) 乙基)] 氨基ac啶 (烷基 = 甲基或乙基) 已被用作铂 (If) 的配体。最终产物是一种复合物,其中a啶充当三齿配体,贡献两个环外氮原子和两个环碳之一。金属化主要发生在未取代环的周围位置。配位的a啶呈亚氨基互变异构形式,尽管在自由状态下,它仅以氨基形式存在 (固态和溶液中)。亚氨基互变异构体被认为是生物活性形式。在铂化物质中,吖啶的N(10)H可能参与与氯离子的强氢键,导致缔合配合物的形成,已发现形成常数为1.4 +/-10(3) M(-1)。N(10)H...CI相互作用也会在不协调的物种中影响吖啶染料的互变异构平衡,但是,有利于亚氨基互变异构体的转变尚未完成。
  • 【迈克尔反应受体作为防止致癌的酶诱导剂的效力取决于其与巯基的反应性。】 复制标题 收藏 收藏
    DOI:10.1073/pnas.051632198 复制DOI
    作者列表:Dinkova-Kostova AT,Massiah MA,Bozak RE,Hicks RJ,Talalay P
    BACKGROUND & AIMS: :Induction of phase 2 enzymes and elevations of glutathione are major and sufficient strategies for protecting mammals and their cells against the toxic and carcinogenic effects of electrophiles and reactive forms of oxygen. Inducers belong to nine chemical classes and have few common properties except for their ability to modify sulfhydryl groups by oxidation, reduction, or alkylation. Much evidence suggests that the cellular "sensor" molecule that recognizes the inducers and signals the enhanced transcription of phase 2 genes does so by virtue of unique and highly reactive sulfhydryl functions that recognize and covalently react with the inducers. Benzylidene-alkanones and -cycloalkanones are Michael reaction acceptors whose inducer potency is profoundly increased by the presence of ortho- (but not other) hydroxyl substituent(s) on the aromatic ring(s). This enhancement correlates with more rapid reactivity of the ortho-hydroxylated derivatives with model sulfhydryl compounds. Proton NMR spectroscopy provides no evidence for increased electrophilicity of the beta-vinyl carbons (the presumed site of nucleophilic attack) on the hydroxylated inducers. Surprisingly, these ortho-hydroxyl groups display a propensity for extensive intermolecular hydrogen bond formation, which may raise the reactivity and facilitate addition of mercaptans, thereby raising inducer potencies.
    背景与目标: : 2相酶的诱导和谷胱甘肽的升高是保护哺乳动物及其细胞免受亲电试剂和反应性氧气的毒性和致癌作用的主要而充分的策略。诱导剂属于九种化学类别,除了具有通过氧化,还原或烷基化修饰巯基的能力外,几乎没有共同的性质。许多证据表明,识别诱导物并发出增强的2期基因转录信号的细胞 “传感器” 分子是通过识别诱导物并与诱导物共价反应的独特且高反应性的巯基功能实现的。亚苄基链烷酮和-环烷酮是迈克尔反应受体,其诱导剂效力因芳环上邻位 (而不是其他) 羟基取代基的存在而大大提高。这种增强与邻位羟基化衍生物与模型巯基化合物的更快反应性相关。质子NMR光谱没有提供增加 β-乙烯基碳 (假定的亲核攻击位点) 对羟基化诱导剂的亲电性的证据。令人惊讶的是,这些邻羟基显示出广泛的分子间氢键形成的倾向,这可能会提高反应性并促进硫醇的添加,从而提高诱导剂的效力。
  • 【电子受体通过促进GspD组装,在厌氧条件下诱导产肠毒素大肠杆菌热不稳定肠毒素的分泌。】 复制标题 收藏 收藏
    DOI:10.1128/IAI.00358-16 复制DOI
    作者列表:Lu X,Fu E,Xie Y,Jin F
    BACKGROUND & AIMS: :Heat-labile enterotoxin (LT), the major virulence factor of enterotoxigenic Escherichia coli (ETEC), can lead to severe diarrhea and promotes ETEC adherence to intestinal epithelial cells. Most previous in vitro studies focused on ETEC pathogenesis were conducted under aerobic conditions, which do not reflect the real situation of ETEC infection because the intestine is anoxic. In this study, the expression and secretion of LT under anaerobic or microaerobic conditions were determined; LT was not efficiently secreted into the supernatant under anaerobic or microaerobic conditions unless terminal electron acceptors (trimethylamine N-oxide dihydrate [TMAO] or nitrate) were available. Furthermore, we found that the restoration effects of TMAO and nitrate on LT secretion could be inhibited by amytal or ΔtorCAD and ΔnarG E. coli strains, indicating that LT secretion under anaerobic conditions was dependent on the integrity of the respiratory chain. At the same time, electron acceptors increase the ATP level of ETEC, but this increase was not the main reason for LT secretion. Subsequently, the relationship between the integrity of the respiratory chain and the function of the type II secretion system was determined. The GspD protein, the secretin of ETEC, was assembled under anaerobic conditions and was accompanied by LT secretion when TMAO or nitrate was added. Our data also demonstrated that TMAO and nitrate could not induce the GspD assembly and LT secretion in ΔtorCAD and ΔnarG strains, respectively. Moreover, GspD assembly under anaerobic conditions was assisted by the pilot protein YghG.
    背景与目标: : 不耐热肠毒素 (LT) 是产肠毒素大肠杆菌 (ETEC) 的主要毒力因子,可导致严重腹泻并促进ETEC粘附于肠上皮细胞。以前大多数针对ETEC发病机理的体外研究都是在有氧条件下进行的,由于肠道是缺氧的,因此无法反映ETEC感染的真实情况。在这项研究中,确定了在厌氧或微需氧条件下LT的表达和分泌; 除非有末端电子受体 (三甲胺N-氧化物二水合物 [TMAO] 或硝酸盐),否则在厌氧或微需氧条件下LT不能有效地分泌到上清液中。此外,我们发现TMAO和硝酸盐对LT分泌的恢复作用可以被amytal或 Δ torcad和 Δ narg大肠杆菌菌株抑制,表明厌氧条件下的LT分泌取决于呼吸链的完整性。同时,电子受体增加了ETEC的ATP水平,但这种增加不是LT分泌的主要原因。随后,确定了呼吸链的完整性与II型分泌系统功能之间的关系。GspD蛋白 (ETEC的分泌素) 在厌氧条件下组装,并在添加TMAO或硝酸盐时伴随着LT分泌。我们的数据还表明,TMAO和硝酸盐分别不能诱导 Δ torcad和 Δ narg菌株中的GspD组装和LT分泌。此外,在厌氧条件下,GspD组装由先导蛋白YghG协助。
  • 【用于高性能有机太阳能电池的具有近红外吸收的非共价稠合环电子受体。】 复制标题 收藏 收藏
    DOI:10.1038/s41467-019-11001-6 复制DOI
    作者列表:Huang H,Guo Q,Feng S,Zhang C,Bi Z,Xue W,Yang J,Song J,Li C,Xu X,Tang Z,Ma W,Bo Z
    BACKGROUND & AIMS: :Non-fullerene fused-ring electron acceptors boost the power conversion efficiency of organic solar cells, but they suffer from high synthetic cost and low yield. Here, we show a series of low-cost noncovalently fused-ring electron acceptors, which consist of a ladder-like core locked by noncovalent sulfur-oxygen interactions and flanked by two dicyanoindanone electron-withdrawing groups. Compared with that of similar but unfused acceptor, the presence of ladder-like structure markedly broadens the absorption to the near-infrared region. In addition, the use of intramolecular noncovalent interactions avoids the tedious synthesis of covalently fused-ring structures and markedly lowers the synthetic cost. The optimized solar cells displayed an outstanding efficiency of 13.24%. More importantly, solar cells based on these acceptors demonstrate very low non-radiative energy losses. This research demonstrates that low-cost noncovalently fused-ring electron acceptors are promising to achieve high-efficiency organic solar cells.
    背景与目标: : 非富勒烯稠环电子受体提高了有机太阳能电池的功率转换效率,但它们的合成成本高且收率低。在这里,我们展示了一系列低成本的非共价稠合环电子受体,该受体由被非共价硫-氧相互作用锁定的梯形核组成,两侧是两个二氰基茚满酮吸电子基团。与相似但未融合的受体相比,梯形结构的存在显着扩大了对近红外区域的吸收。此外,使用分子内非共价相互作用避免了共价稠环结构的繁琐合成,并显着降低了合成成本。优化后的太阳能电池显示出出色的13.24% 效率。更重要的是,基于这些受体的太阳能电池显示出非常低的非辐射能量损失。这项研究表明,低成本的非共价稠环电子受体有望实现高效有机太阳能电池。
  • 【有机膦氟化物受体对水性介质中生物分子的快速一步18f放射性标记。】 复制标题 收藏 收藏
    DOI:10.1038/s41467-019-08953-0 复制DOI
    作者列表:Hong H,Zhang L,Xie F,Zhuang R,Jiang D,Liu H,Li J,Yang H,Zhang X,Nie L,Li Z
    BACKGROUND & AIMS: :Currently, only a few 18F-radiolabeling methods were conducted in aqueous media, with non-macroelement fluoride acceptors and stringent conditions required. Herein, we describe a one-step non-solvent-biased, room-temperature-driven 18F-radiolabeling methodology based on organophosphine fluoride acceptors. The high water tolerance for this isotope-exchange-based 18F-labeling method is attributed to the kinetic and thermodynamic preference of F/F over the OH/F substitution based on computational calculations and experimental validation. Compact [18/19F]di-tert-butyl-organofluorophosphine and its derivatives used as 18F-labeling synthons exhibit excellent stability in vivo. The synthons are further conjugated to several biomolecular ligands such as c(RGDyk) and human serum albumin. The one-step labeled biomolecular tracers demonstrate intrinsic target imaging ability and negligible defluorination in vivo. The current method thus offers a facile and efficient 18F-radiolabeling pathway, enabling further widespread application of 18F.
    背景与目标: : 目前,在非大分子氟化物受体和严格的条件下,在水性介质中仅进行了几种18f放射性标记方法。在这里,我们描述了一种基于有机膦氟化物受体的一步非溶剂偏置,室温驱动的18f放射性标记方法。基于计算计算和实验验证,这种基于同位素交换的18f标记方法的高耐水性归因于F/F相对于OH/F取代的动力学和热力学偏好。紧凑型 [18/19F] 二叔丁基-有机氟膦及其用作18f-标记合成子的衍生物在体内表现出优异的稳定性。该合成子进一步与几个生物分子配体如c(RGDyk) 和人血清白蛋白偶联。一步标记的生物分子示踪剂展示了内在的靶成像能力和可忽略的体内脱氟。因此,当前的方法提供了一种简便有效的18f放射性标记途径,使18F进一步广泛应用。
  • 【孟加拉国受体中Norplant避孕皮下植入物的五年临床评估。】 复制标题 收藏 收藏
    DOI:10.1016/0010-7824(93)90024-2 复制DOI
    作者列表:Akhter H,Dunson TR,Amatya RN,Begum K,Chowdhury T,Dighe N,Krueger SL,Rahman S
    BACKGROUND & AIMS: A non-comparative study of the Norplant contraceptive subdermal implant system was conducted in Dhaka, Bangladesh. The study was designed to evaluate the contraceptive efficacy, safety and overall acceptability of Norplant implants. Six hundred women were enrolled in the clinical trial, which began in 1985 at three study sites. Follow-up visits were scheduled at 1, 3, and 6 months after Norplant implant insertion, and every six months thereafter until removal or at the end of five years. There were no post-insertion pregnancies during Norplant implant use in this study. After five years of Norplant implant use, there was no clinically significant change in body weight, systolic or diastolic blood pressure. Less than 3% of the women ever reported having any significant medical problems such as migraine, respiratory or cardiac problems during the study. The gross cumulative continuation rate was 41.2 per 100 women at the end of five years. The two most frequently reported reasons for discontinuation during the study were menstrual problems and desired pregnancy. Of the women who completed the five-year user satisfaction questionnaire, the majority of the women (86.3%) planned to continue using contraception after study completion. Of these women, approximately one-third said they planned to use another Norplant set. The findings presented suggest that the Norplant system is a highly effective, safe and acceptable method among Bangladeshi women.

    From February 1985 to February 1986, researchers enrolled 600 18-40 year old women at the Dhaka Medical College and Hospital, the Institute of Postgraduate Medicine and Research, and the Mohammadpur Fertility Services and Training Centre in a 5-year clinical trial to evaluate the contraceptive efficacy, safety, and acceptability of Norplant subdermal implants in Bangladesh. They scheduled the women to return for follow-up visits 1, 3, and 6 months after insertion and every 6 months thereafter until removal or at the end of 5 years. No pregnancies after insertion occurred during the study. The gross cumulative continuation rate was 93.9% at 1 year and 72.3% at 2 years. The 5-year cumulative continuation rate was 41.2% which was much lower than that in other Asian countries (e.g., 52.3% in Sri Lanka and 78.2% in Indonesia). The 5-year cumulative discontinuation rate for menstrual problems was 30.7% which was higher than that of other studies. It may have been higher because Bangladeshi women do not tolerate well and accept changes in bleeding patterns, especially since menstrual bleeding prevents them from prayer and taking part in sexual activity. 45.3% of all women requesting early Norplant removal complained of menstrual problems, especially prolonged heavy bleeding (75% of women requesting removal for menstrual problems). Most menstrual problem removals took place during the 2nd year and fell thereafter. Desired pregnancy was the second most common reason for removal (18.6%). The gross discontinuation rate for nonmenstrual side effects was just 2.2%, the main side effect being headaches. 97.5% of women who completed the 5-year study considered their experience with Norplant favorable. The leading reason for a favorable rating for Norplant was its duration of use (64.5%). Menstrual changes comprised the least favorable component of Norplant among women who completed the study (63.3%). 33% of women still wanting to use contraception after 5 years of Norplant use said they would use Norplant again.

    背景与目标: 在孟加拉国达卡进行了Norplant避孕皮下植入系统的非比较研究。该研究旨在评估Norplant植入物的避孕功效,安全性和总体可接受性。600名妇女参加了临床试验,该试验在三个研究地点开始1985年。计划在插入Norplant植入物后的1、3和6个月进行随访,此后每六个月进行一次随访,直到移除或五年结束。在这项研究中,在使用Norplant植入物期间没有插入后怀孕。使用Norplant植入物五年后,体重,收缩压或舒张压无临床显着变化。在研究期间,只有不到3% 的女性报告有任何重大的医学问题,例如偏头痛,呼吸系统或心脏问题。在五年结束时,总累积延续率为每100名妇女41.2。研究期间停药的两个最常报告的原因是月经问题和预期怀孕。在完成五年用户满意度问卷的妇女中,大多数妇女 (86.3%) 计划在研究完成后继续使用避孕措施。在这些妇女中,大约3分之1人说他们计划使用另一套Norplant。提出的研究结果表明,Norplant系统是孟加拉国妇女中非常有效,安全和可接受的方法。
    从1985年2月到1986年2月,研究人员在达卡医学院和医院,研究生医学和研究所招募了600名18-40岁的妇女,和Mohammadpur生育服务和培训中心进行了为期5年的临床试验,以评估孟加拉国Norplant皮下植入物的避孕功效,安全性和可接受性。他们安排这些妇女在插入后1、3和6个月返回进行随访,此后每6个月返回一次,直到取出或5年结束。在研究期间,插入后没有怀孕。总累积延续率在1年时93.9%,在2年时72.3%。5年累积延续率41.2%,远低于其他亚洲国家 (例如,斯里兰卡的52.3% 和印度尼西亚的78.2%)。月经问题的5年累积停药率为30.7%,高于其他研究。它可能更高,因为孟加拉国妇女不能很好地忍受和接受出血模式的变化,特别是因为月经出血阻止她们祈祷和参与性活动。所有要求早期去除Norplant的妇女的45.3% 抱怨月经问题,特别是长期大量出血 (75% 要求去除月经问题的妇女)。大多数月经问题清除发生在第二年,此后下降。期望怀孕是第二个最常见的切除原因 (18.6%)。非月经副作用的总停药率仅为2.2%,主要副作用是头痛。完成5年研究的女性97.5% 认为她们在Norplant的经历是有利的。Norplant获得良好评级的主要原因是其使用期限 (64.5%)。在完成研究的女性中,月经变化是Norplant最不利的成分 (63.3%)。使用Norplant 5年后仍想使用避孕药的妇女中有33% 表示将再次使用Norplant。
  • 【N-氨基-N'-羟基胍腙作为黄嘌呤氧化酶电子受体的合成及其定量构效关系.】 复制标题 收藏 收藏
    DOI:10.1021/jm031127c 复制DOI
    作者列表:Prusis P,Dambrova M,Andrianov V,Rozhkov E,Semenikhina V,Piskunova I,Ongwae E,Lundstedt T,Kalvinsh I,Wikberg JE
    BACKGROUND & AIMS: :A series of new N-hydroxyguanidines were synthesized and tested for electron acceptor activity on bovine milk xanthine oxidase using xanthine as reducing substrate. Manual inspection of the structure-activity data revealed that molecules containing nitro groups ("set A") show a different structure-activity relationship pattern compared to non-nitro compounds ("set B"). Accordingly separate QSAR models were built and validated for the two sets. Substantial differences were found in properties governing acceptor activity for the models, the only common property being sterical access to the imino nitrogen atom of the hydroxyguanidinimines. For set A molecules the presence of a nitro substituent at a certain distance range from the hydroxuguanidino group was most important. In addition, the presence of a nitro group in the ortho position interacting with NH(2) of the hydroxyguanidino group, and the mutual geometry of the phenyl ring, hydroxyguanidine, and imine groups was important for this set. By contrast, for set B molecules the acceptor activity was most influenced by the geometry of methoxy groups and the size and geometry of meta and para substituents of the phenyl ring.
    背景与目标: : 以黄嘌呤为还原底物,合成了一系列新的N-羟基胍,并测试了牛乳黄嘌呤氧化酶的电子受体活性。手动检查结构活性数据显示,与非硝基化合物 (“B组”) 相比,含有硝基的分子 (“A组”) 显示出不同的结构活性关系模式。因此,为这两组建立并验证了单独的QSAR模型。在控制模型受体活性的性质上发现了实质性差异,唯一的共同性质是对羟基胍亚胺的亚氨基氮原子的空间进入。对于set A分子,最重要的是与氢xuguanidino基团在一定距离范围内存在硝基取代基。此外,在与羟基胍基的NH(2) 相互作用的邻位中存在硝基基团,以及苯环,羟基胍和亚胺基团的相互几何形状对于该组很重要。相比之下,对于set B分子,受体活性受甲氧基的几何形状以及苯环的间位和对位取代基的大小和几何形状的影响最大。
  • 【紧密堆积,低重组能量 π 扩展的富勒烯后受体,用于高效聚合物太阳能电池。】 复制标题 收藏 收藏
    DOI:10.1073/pnas.1807535115 复制DOI
    作者列表:Swick SM,Zhu W,Matta M,Aldrich TJ,Harbuzaru A,Lopez Navarrete JT,Ponce Ortiz R,Kohlstedt KL,Schatz GC,Facchetti A,Melkonyan FS,Marks TJ
    BACKGROUND & AIMS: :New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b']dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c']dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π-π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.
    背景与目标: : 新型有机半导体对于开发廉价,高效,可溶液处理的聚合物太阳能电池 (psc) 至关重要。PSC光活性层通常通过薄膜浇铸供体聚合物和富勒烯受体共混物来制造,随后进行溶剂蒸发和相分离,从而为光生空穴和电子形成离散的导管。直到最近,n型富勒烯受体仍在PSC文献中占主导地位; 然而,基于茚并二噻吩 (IDTT) 的受体最近启用了显着的PSC性能指标,原因并不完全明显。我们报告了两种基于IDTT的异构受体3,9-双 (2-亚甲基-(3-(1,1-二氰基亚甲基)-苯并-(5,6) 茚满酮))-5,5,11,11-四 (4-壬基苯基)-二噻吩并 [2,3-d:2 ',3'-d']-s-吲哚 [1,2-b:5,6-b'] 二噻吩 (ITN-C9) 和3,9-双 (2-亚甲基-(3-(1,1-二氰基亚甲基)-苯并 (6,7) 吲哚酮))-5,5,11,11-四 (4-壬基苯基)-二噻吩并 [2,3-d:2 ',3'-d']-s-吲哚并 [1,2-b:5,6-b'] 二噻吩 (ITzN-C9) 揭示了相对于富勒烯的特殊IDTT特性。纯净的受体和与氟聚合物供体聚 {[4,8-双 [5-(2-乙基己基)-4-氟-2-噻吩基] 苯并 [1,2-b:4,5-b'] 二噻吩e2,6-二基]-alt-[2,5-噻吩二基 [5,7-双 (2-乙基己基)-4,8-二氧代氧4h,8h-苯并 [1,2-c:4,5-c']dithiophene-1,3-二基]} (PBDB-TF) 通过光学光谱学,循环伏安法,热重分析,差示扫描量热法,单晶x射线衍射,光伏响应,空间电荷限制电流传输,原子力显微镜、掠入射广角x射线散射和密度泛函理论水平的量子化学分析。数据揭示了ITN-C9和ITzN-C9组织,使得最低的未占据的富含分子轨道的端基具有接近3.31(1) Å 的分子间 π-π 距离,电子耦合积分大到38 meV,内部重组能量小到0.133 eV,与富勒烯相当或优于富勒烯。ITN-C9和ITzN-C9具有广泛的太阳能相关光吸收,当与PBDB-TF混合时,提供功率转换效率接近10% 的器件。ITN-C9和ITzN-C9之间的性能差异通过对分子堆积和相对于电极的取向的影响而在分子和电子结构区别方面是可以理解的。
  • 【在模拟的低压火星条件下,向固体介质中添加厌氧电子受体不会增强125航天器细菌的生长。】 复制标题 收藏 收藏
    DOI:10.1038/s41598-020-75222-2 复制DOI
    作者列表:Schwendner P,Jobson ME,Schuerger AC
    BACKGROUND & AIMS: :To protect Mars from microbial contamination, research on growth of microorganisms found in spacecraft assembly clean rooms under simulated Martian conditions is required. This study investigated the effects of low atmospheric pressure on the growth of chemoorganotrophic spacecraft bacteria and whether the addition of Mars relevant anaerobic electron acceptors might enhance growth. The 125 bacteria screened here were recovered from actual Mars spacecraft. Growth at 7 hPa, 0 °C, and a CO2-enriched anoxic atmosphere (called low-PTA conditions) was tested on five TSA-based media supplemented with anaerobic electron acceptors. None of the 125 spacecraft bacteria showed active growth under the tested low-PTA conditions and amended media. In contrast, a decrease in viability was observed in most cases. Growth curves of two hypopiezotolerant strains, Serratia liquefaciens and Trichococcus pasteurii, were performed to quantify the effects of the added anaerobic electron acceptors. Slight variations in growth rates were determined for both bacteria. However, the final cell densities were similar for all media tested, indicating no general preference for any specific anaerobic electron acceptor. By demonstrating that a broad diversity of chemoorganotrophic and culturable spacecraft bacteria do not grow under the tested conditions, we conclude that there may be low risk of growth of chemoorganotrophic bacteria typically recovered from Mars spacecraft during planetary protection bioburden screenings.
    背景与目标: : 为了保护火星免受微生物污染,需要研究在模拟火星条件下在航天器组件洁净室中发现的微生物的生长。这项研究调查了低大气压对化学有机营养航天器细菌生长的影响,以及添加火星相关的厌氧电子受体是否可能促进生长。这里筛选的125细菌是从实际的火星航天器中回收的。在5种补充有厌氧电子受体的基于TSA的培养基上测试了7 hPa,0 °C和CO2-enriched缺氧气氛 (称为低PTA条件) 下的生长。在测试的低PTA条件和修正的培养基下,没有125航天器细菌显示出活跃的生长。相反,在大多数情况下观察到生存能力下降。进行了两种低唑的生长曲线,即沙雷氏菌和巴氏曲霉,以量化添加的厌氧电子受体的作用。确定了两种细菌的生长速率略有变化。但是,所有测试的培养基的最终细胞密度相似,表明对任何特定的厌氧电子受体都没有普遍偏爱。通过证明在测试条件下不会生长广泛的化学有机营养和可培养的航天器细菌,我们得出结论,在行星保护生物负荷筛选期间,通常从火星航天器中回收的化学有机营养细菌的生长风险可能较低。
  • 【甲基化组和代谢组分析揭示了在不同末端电子受体上生长的硫化杆菌中的适应性机制。】 复制标题 收藏 收藏
    DOI:10.1021/acs.jproteome.8b00763 复制DOI
    作者列表:Shi Z
    BACKGROUND & AIMS: :The Geobacter species evolved respiratory versatility to utilize a wide range of terminal electron acceptors. To explore this adaptive mechanism, Fe(III) citrate, hydrous ferric oxide, and fumarate were selected as electron acceptors, and the methylome and metabolome of Geobacter sulfurreducens PCA grown on each electron acceptor were investigated via third-generation, single-molecule real-time DNA sequencing and gas chromatography/time-of-flight mass spectrometry-based metabolomics, respectively. Results showed that the patterns of 4-methylcytosine (m4C) and 6-methyladenine (m6A) modification, the concentrations of fatty acids (e.g., caprylic acid, capric acid, and squalene), and the activity of antioxidant enzymes (e.g., superoxide dismutase, catalase, and glutathione reductase) were all varied in different electron acceptor cultures. Moreover, genes (e.g., GSU0466 and GSU1467) with low expression levels generally had high methylation levels. These findings suggest that m4C and m6A modifications, fatty acids, and antioxidant enzymes all play a role in the adaptation of G. sulfurreducens to diverse electron acceptors, and DNA methylation may be involved in the adaptation mainly via gene expression regulation.
    背景与目标: : Geobacter物种进化出呼吸多功能性,以利用多种末端电子受体。为了探索这种适应性机制,选择了柠檬酸Fe(III),水合三氧化二铁和富马酸盐作为电子受体,并通过第三代研究了在每个电子受体上生长的硫还原杆菌PCA的甲基化组和代谢组,分别基于单分子实时DNA测序和气相色谱/飞行时间质谱的代谢组学。结果表明,4-甲基胞嘧啶 (m4C) 和6-甲基腺嘌呤 (m6A) 修饰的模式,脂肪酸 (例如辛酸,癸酸和角鲨烯) 的浓度以及抗氧化酶 (例如超氧化物歧化酶,过氧化氢酶,和谷胱甘肽还原酶) 在不同的电子受体培养中均有所不同。此外,低表达水平的基因 (例如GSU0466和GSU1467) 通常具有高甲基化水平。这些发现表明,m4C和m6A修饰,脂肪酸和抗氧化酶都在硫还原酶对多种电子受体的适应中起作用,DNA甲基化可能主要通过基因表达调控参与适应。
  • 【中链酰基辅酶a脱氢酶的替代电子受体: 铁鎓盐的使用。】 复制标题 收藏 收藏
    DOI:10.1021/bi00499a004 复制DOI
    作者列表:Lehman TC,Thorpe C
    BACKGROUND & AIMS: :Medium-chain acyl-CoA dehydrogenase reduced with octanoyl-CoA is reoxidized in two one-electron steps by two molecules of the physiological oxidant, electron transferring flavoprotein (ETF). The organometallic oxidant ferricenium hexafluorophosphate (Fc+PF6-) is an excellent alternative oxidant of the dehydrogenase and mimics a number of the features shown by ETF. Reoxidation of octanoyl-CoA-reduced enzyme (200 microM Fc+PF6- in 100 mM Hepes buffer, pH 7.6, 1 degree C) occurs in two one-electron steps with pseudo-first-order rate constants of 40 s-1 and about 200 s-1 for k1 and k2, respectively. The reaction is comparatively insensitive to ionic strength, and evidence of rate saturation is encountered at high ferricenium ion concentration. As observed with ETF, the free two-electron-reduced dehydrogenase is a much poorer kinetic reductant of Fc+PF6-, with rate constants of 3 s-1 and 0.3 s-1 (for k1 and k2, respectively) using 200 microM Fc+PF6-. In addition to the enoyl-CoA product formed during the dehydrogenation of octanoyl-CoA, binding a number of redox-inert acyl-CoA analogues (notably 3-thia- and 3-oxaoctanoyl-CoA) significantly accelerates electron transfer from the dehydrogenase to Fc+PF6-. Those ligands most effective at accelerating electron transfer favor deprotonation of reduced flavin species in the acyl-CoA dehydrogenase. Thus this rate enhancement may reflect the anticipated kinetic superiority of anionic flavin forms as reductants in outer-sphere electron-transfer processes. Evidence consistent with the presence of two distinct loci for redox communication with the bound flavin in the acyl-CoA dehydrogenase is presented.
    背景与目标: : 用辛酰辅酶a还原的中链酰基辅酶a脱氢酶在两个单电子步骤中被两分子生理氧化剂电子转移黄素蛋白 (ETF) 重新氧化。有机金属氧化剂六氟磷酸铁 (Fc PF6-) 是脱氢酶的出色替代氧化剂,并模仿了ETF显示的许多特征。辛酰基辅酶a还原酶 (200 microM Fc + PF6-在100 mM Hepes缓冲液中,pH 7.6,1 ℃) 的再氧化在两个单电子步骤中发生,k1和k2的伪一级速率常数分别为40 s-1和约200 s-1。该反应对离子强度相对不敏感,在高铁离子浓度下会遇到速率饱和的证据。如用ETF观察到的,游离的双电子还原脱氢酶是Fc + PF6-的差得多的动力学还原剂,使用200 microM Fc + PF6-的速率常数为3 s-1和0.3 s-1 (分别为k1和k2)。除了在辛酰基-CoA脱氢过程中形成的烯酰辅酶a产物外,结合许多氧化还原惰性酰基-CoA类似物 (尤其是3-thia-和3-氧辛酰基-CoA) 还显着加速了电子转移从脱氢酶到Fc PF6-。那些最有效地加速电子转移的配体有利于酰基辅酶a脱氢酶中还原黄素物种的去质子化。因此,这种速率提高可能反映了阴离子黄素形式作为外球电子转移过程中还原剂的预期动力学优势。提出了与酰基辅酶a脱氢酶中与结合的黄素进行氧化还原通讯的两个不同基因座相一致的证据。
  • 【光系统I中两个早期电子受体的光谱和动力学证据。】 复制标题 收藏 收藏
    DOI:10.1073/pnas.76.2.770 复制DOI
    作者列表:Shuvalov VA,Dolan E,Ke B
    BACKGROUND & AIMS: :Triton-fractionated photosystem-I particles poised at -625 mV, where the two bound iron-sulfur proteins are reduced, have been studied by optical and electron paramagnetic resonance spectroscopies from 293 to 5 K. At 5-9 K, these particles exhibit two decay components with lifetimes of 1.3 and 130 msec in the laser pulse-induced absorption and electron paramagnetic resonance signal changes. Spectral properties of the 130-msec decay component reflect the charge separation between P-700 and some iron-sulfur center having a broad optical absorbance in the 400- to 550-nm region and a previously reported electron paramagnetic resonance signal with g = 1.78, 1.88, and 2.08. Spectral properties of the 1-msec decay component indicate photoinduced charge separation between P-700 and a chlorophyll a dimer having absorption bands at 420, 450, and 700 nm. It is assumed that these two acceptors participate in the electron transfer from P-700(*) to the bound iron-sulfur proteins.
    背景与目标: : 已通过光学和电子顺磁共振光谱从293 K到5 K研究了位于-625 mV的Triton分级的光系统I颗粒,其中两个结合的铁硫蛋白被还原。在5-9 K时,这些粒子在激光脉冲诱导的吸收和电子顺磁共振信号变化中表现出两种寿命为1.3和130毫秒的衰变分量。130毫秒衰减分量的光谱特性反映了P-700与某些铁硫中心之间的电荷分离,该铁硫中心在400至550纳米区域具有宽的光吸收,并且先前报道的电子顺磁共振信号具有g = 1.78、1.88和2.08。1毫秒衰减组分的光谱特性指示P-700和叶绿素a二聚体之间的光诱导电荷分离,叶绿素a二聚体具有在420、450和700 nm处的吸收带。假定这两个受体参与了从P-700(*) 到结合的铁硫蛋白的电子转移。
  • 【氯酚和各种传统电子受体利用过程中脱卤脱卤杆菌的能量和生长产量的比较。】 复制标题 收藏 收藏
    DOI:10.1128/AEM.64.1.352-355.1998 复制DOI
    作者列表:Mackiewicz M,Wiegel J
    BACKGROUND & AIMS: :Desulfitobacterium dehalogenans grew with formate as the electron donor and 3-chloro-4-hydroxyphenylacetate (3-Cl-4-OHPA) as the electron acceptor, yielding Y(X/formate), Y(X/2e), and Y(X/ATP) ranging from 3.2 to 11.3 g of biomass (dry weight)/mol, thus indicating that energy was conserved through reductive dechlorination. Pyruvate was utilized as the electron donor and acceptor, yielding stoichiometric amounts of acetate and lactate, respectively, and a Y(X/reduced acceptor) of 13.0 g of biomass (dry weight)/mol. The supplementation of pyruvate-containing medium with additional electron acceptors, such as 3-Cl-4-OHPA, nitrate, fumarate, or sulfite, caused pyruvate to be replaced as the electron acceptor and nearly doubled the Y(X/ATP) (Y(X/acetate formed)). A comparison of the yields for 3-Cl-4-OHPA with those for other traditional electron acceptors indicates that the dehalogenation reaction led to the formation of similar amounts of energy equivalents. The various electron acceptors were used concomitantly with 3-Cl-4-OHPA in nonacclimated cultures, but the utilization rates and amounts utilized differed.
    背景与目标: : 以甲酸盐为电子供体,以3-氯-4-羟基苯乙酸盐 (3-Cl-4-OHPA) 为电子受体,产生Y(X/甲酸盐),Y(X/2e) 和Y(X/ATP),范围为3.2至11.3g生物质 (干重)/mol,因此表明通过还原脱氯保存了能量。丙酮酸用作电子供体和受体,分别产生化学计量量的乙酸盐和乳酸,以及13.0克生物质 (干重)/摩尔的Y(X/还原受体)。用其他电子受体 (例如3-Cl-4-OHPA,硝酸盐,富马酸酯或亚硫酸盐) 补充含丙酮酸的介质,导致丙酮酸被替换为电子受体,并使Y(X/ATP) (Y(X/乙酸盐形成))。3-Cl-4-OHPA的产率与其他传统电子受体的产率的比较表明,脱卤反应导致形成相似量的能量当量。在不适应的培养物中,各种电子受体与3-Cl-4-OHPA同时使用,但是利用率和使用量有所不同。

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