Electrostatic and steric effects in the selective complexation of cations in nonactin

The ester carbonyl stretch frequencies of complexes of the macrotetrolide nonactin with Na(+), K(+), Rb(+), Cs(+), Tl(+), NH(4)(+), NH(3)OH(+), and (NH(2))(2)CNH(2)(+) have been measured. For the larger alkali cations and the polyatomic cations, the ester carbonyl stretch frequency is linearly proportional to the cation-ester carbonyl electrostatic interaction energy. This constitutes direct evidence that the cation-nonactin interaction is primarily electrostatic, rather than mechanical (steric).     

Chemical and genetic engineering of selective ion channel-ligand interactions

Ionic flux mediates essential physiological and behavioral functions in defined cell populations. Cell type-specific activators of diverse ionic conductances are needed for probing these effects. We combined chemistry and protein engineering to enable the systematic creation of a toolbox of ligand-gated ion channels (LGICs) with orthogonal pharmacologic selectivity and divergent functional properties. The LGICs and their small-molecule effectors were able to activate a range of ionic conductances in genetically specified cell types. LGICs constructed for neuronal perturbation could be used to selectively manipulate neuron activity in mammalian brains in vivo. The diversity of ion channel tools accessible from this approach will be useful for examining the relationship between neuronal activity and animal behavior, as well as for cell biological and physiological applications requiring chemical control of ion conductance.     

Reconciling the magnitude of the microscopic and macroscopic hydrophobic effects

The magnitude of the hydrophobic effect, as measured from the surface area dependence of the solubilities of hydrocarbons in water, is generally thought to be about 25 calories per mole per square angstrom (cal mol-1 A-2). However, the surface tension at a hydrocarbon-water interface, which is a "macroscopic" measure of the hydrophobic effect, is approximately 72 cal mol-1 A-2. In an attempt to reconcile these values, alkane solubility data have been reevaluated to account for solute-solvent size differences, leading to a revised "microscopic" hydrophobic effect of 47 cal mol-1 A-2. This value, when used in a simple geometric model for the curvature dependence of the hydrophobic effect, predicts a macroscopic alkane-water surface tension that is close to the macroscopic value.     

Water at hydrophobic surfaces: weak hydrogen bonding and strong orientation effects

Vibrational studies that selectively probe molecular structure at CCl4/H2O and hydrocarbon/H2O interfaces show that the hydrogen bonding between adjacent water molecules at these interfaces is weak, in contrast to generally accepted models of water next to fluid hydrophobic surfaces that suggest strong hydrogen bonding. However, interactions between these water molecules and the organic phase result in substantial orientation of these weakly hydrogen-bonded water molecules in the interfacial region. The results have important implications for understanding water adjacent to hydrophobic surfaces and the penetration of water into hydrophobic phases.     

Progress in modeling of protein structures and interactions

The prediction of the structures and interactions of biological macromolecules at the atomic level and the design of new structures and interactions are critical tests of our understanding of the interatomic interactions that underlie molecular biology. Equally important, the capability to accurately predict and design macromolecular structures and interactions would streamline the interpretation of genome sequence information and allow the creation of macromolecules with new and useful functions. This review summarizes recent progress in modeling that suggests that we are entering an era in which high-resolution prediction and design will make increasingly important contributions to biology and medicine.     

迟钝爱德华氏菌外膜蛋白基因工程表达产物的免疫原性

构建迟钝爱德华氏菌外膜蛋白重组表达载体后,表达纯化获得分子质量约53ku的外膜蛋白。将100尾日本鳗鲡均分为2组,分别腹腔注射牛血清白蛋白(BSA,0.5mg/mL)和迟钝爱德华氏菌外膜蛋白(Omp,0.5mg/mL)0.2mL/尾。于免疫后第7、14和28天采集鳗鲡血液、粘液、肝脏和肾脏,测定各时间点的补体活性、溶菌酶活性、全血细胞转化水平和血清抗体效价。结果发现,外膜蛋白组鳗鲡的补体活性于免疫后第7天极显著高于对照组;其抗体效价于第14天和第28天显著或极显著高于对照组。免疫后第28天以迟钝爱德华氏菌、嗜水气单胞菌和创伤弧菌(1.0×107 cfu)腹腔注射感染鳗鲡。结果发现,外膜蛋白组鳗鲡对迟钝爱德华氏菌、嗜水气单胞菌和创伤弧菌的相对免疫保护率分别为71.4%、50.0%和12.5%。表明鳗鲡注射迟钝爱德华氏菌基因工程表达外膜后显著提高了其对迟钝爱德华氏菌感染的抵抗力,对嗜水气单胞菌的感染也有明显的交叉保护效果,但对创伤弧菌的交叉保护效果较弱。     

微生物发酵蛋白饲料饲喂肉猪效果的研究

一个月的饲喂试验结果表明,微生物发酵蛋白饲料对肉猪适口性好,增重效果明显,提高了胴体品质和脏器指标,增加了经济效益。利用微生物发酵生产蛋白饲料为肉猪养殖业饲料来源增加了新的途径。     

Treatment of ischemic brain damage by perturbing NMDA receptor- PSD-95 protein interactions

N-methyl-D-aspartate receptors (NMDARs) mediate ischemic brain damage but also mediate essential neuronal excitation. To treat stroke without blocking NMDARs, we transduced neurons with peptides that disrupted the interaction of NMDARs with the postsynaptic density protein PSD-95. This procedure dissociated NMDARs from downstream neurotoxic signaling without blocking synaptic activity or calcium influx. The peptides, when applied either before or 1 hour after an insult, protected cultured neurons from excitotoxicity, reduced focal ischemic brain damage in rats, and improved their neurological function. This approach circumvents the negative consequences associated with blocking NMDARs and may constitute a practical stroke therapy.     

高温热处理速生桉木材的疏水性能研究

【目的】揭示速生桉木材的疏水原因,提高速生桉木材的生物耐久性。【方法】速生桉木材分别经180％水蒸汽热处理1、2和4hA,测量接触角、粗糙度,进行FTIR分析、观察表面形貌特征,并对接触角、处理时间和粗糙度进行偏相关分析。【结果】未处理速生桉锯材表面接触角均值为86．57°,热处理锯材表面接触角均在1120以上。随着热处理时间的延长,接触角显著提高,接触角曲线变化趋于平稳有序。亲水官能团羟基在3415．37cm处出现吸收峰,未处理材的峰值吸光值为2．22,热处理1h后吸光值显著下降至1．38,热处理2和4h分别降低至1．34和1．30,降幅明显。亲水官能团羰基在1618．09cm。处出现吸收峰,未处理材的峰值吸光值为0．80,热处理1hA,吸光值轻微下降至0．72,热处理2和4h后均为0．66,下降不再明显。速生桉木材在高温状态下表面发生开裂、扭曲等,影响了表面的平整度,但粗糙度变化并无显著规律。粗糙度与接触角净相关系数为-0．050,完全不相关;接触角和处理时间偏相关系数为0．746,显著相关;处理时间和粗糙度低相关。【结论】经180％水蒸汽热处理后速生桉木材粗糙度与接触角变化无相关性,热处理时间对接触影响显著,热处理温度的提高会啬粗糙度,但不影响木材的疏水性能。     

The effects of enriched carbon dioxide atmospheres on plant--insect herbivore interactions

Little is known about the effects of enriched CO(2) atmospheres, which may exist in the next century, on natural plant-insect herbivore interactions. Larvae of a specialist insect herbivore, Junonia coenia (Lepidoptera: Nymphalidae), were reared on one of its host plants, Plantago lanceolata (Plantaginaceae), grown in either current low (350 parts per million) or high (700 ppm) CO(2) environments. Those larvae raised on high-CO(2) foliage grew more slowly and experienced greater mortality, especially in early instars, than those raised on low-CO(2) foliage. Poor larval performance on high-CO(2) foliage was probably due to the reduced foliar water and nitrogen concentrations of those plants and not to changes in the concentration of the defensive compounds, iridoid glycosides. Adult pupal weight and female fecundity were not affected by the CO(2) environment of the host plant. These results indicate that interactions between plants and herbivorous insects will be modified under the predicted CO(2) conditions of the 21st century.     

Neurotrophic and neurotoxic effects of amyloid beta protein: reversal by tachykinin neuropeptides

The amyloid beta protein is deposited in the brains of patients with Alzheimer's disease but its pathogenic role is unknown. In culture, the amyloid beta protein was neurotrophic to undifferentiated hippocampal neurons at low concentrations and neurotoxic to mature neurons at higher concentrations. In differentiated neurons, amyloid beta protein caused dendritic and axonal retraction followed by neuronal death. A portion of the amyloid beta protein (amino acids 25 to 35) mediated both the trophic and toxic effects and was homologous to the tachykinin neuropeptide family. The effects of the amyloid beta protein were mimicked by tachykinin antagonists and completely reversed by specific tachykinin agonists. Thus, the amyloid beta protein could function as a neurotrophic factor for differentiating neurons, but at high concentrations in mature neurons, as in Alzheimer's disease, could cause neuronal degeneration.     

Antimalarials: effects on in vivo and in vitro protein synthesis

The antimalarials quinine, chloroquine, primaquine, and quinacrine inhibited the uptake and incorporation of amino acids in vivo, but these drugs had considerably less effect on cell-free protein synthesis. The results indicate that the primary effect of the four drugs on protein synthesis is blocking of amino acid uptake by the cells.     

A functional protein chip for pathway optimization and in vitro metabolic engineering

Pathway optimization is difficult to achieve owing to complex, nonlinear, and largely unknown interactions of enzymes, regulators, and metabolites. We report a pathway reconstruction using RNA display-derived messenger RNA-enzyme fusion molecules. These chimeras are immobilized by hybridization of their messenger RNA end with homologous capture DNA spotted on a substrate surface. Enzymes thus immobilized retain activity proportional to the amount of capture DNA, allowing modulation of the relative activity of pathway enzymes. Entire pathways can thus be reconstructed and optimized in vitro from genomic information. We provide concept validation with the sequential reactions catalyzed by luciferase and nucleoside diphosphate kinase and further illustrate this method with the optimization of the five-step pathway for trehalose synthesis.     

Histone H4-K16 acetylation controls chromatin structure and protein interactions

Acetylation of histone H4 on lysine 16 (H4-K16Ac) is a prevalent and reversible posttranslational chromatin modification in eukaryotes. To characterize the structural and functional role of this mark, we used a native chemical ligation strategy to generate histone H4 that was homogeneously acetylated at K16. The incorporation of this modified histone into nucleosomal arrays inhibits the formation of compact 30-nanometer-like fibers and impedes the ability of chromatin to form cross-fiber interactions. H4-K16Ac also inhibits the ability of the adenosine triphosphate-utilizing chromatin assembly and remodeling enzyme ACF to mobilize a mononucleosome, indicating that this single histone modification modulates both higher order chromatin structure and functional interactions between a nonhistone protein and the chromatin fiber.     

饥饿及再投喂对日本囊对虾蛋白质代谢的影响

研究了体重为(13.08±2.40)g、体长为(10.37±0.73)cm的日本囊对虾Marsupenaeus ja-ponicus在饥饿和再投喂状态下蛋白质代谢的变化。对照组C连续饱食投喂10 d,试验组S10、S15、S25分别饥饿10、15、25 d后再恢复饱食投喂10 d。结果表明:在饥饿状态下,日本囊对虾肌肉中蛋白质的含量在饥饿前15 d迅速上升,饥饿第15~25 d趋于平稳,肝胰脏中蛋白质的含量则一直较稳定;恢复投喂后,肌肉中蛋白质的含量下降,而肝胰脏中蛋白质的含量上升。血浆中蛋白质的含量在饥饿前期(0~5 d)保持平稳,但在之后的第5~15 d则迅速下降,最后又恢复至最初水平;恢复投喂后,除S25组外其余各组血浆中蛋白质的含量都呈上升趋势,且试验组显著高于对照组(P<0.05)。肌肉中RNA/DNA的值在饥饿初期(0~5 d)略有下降,之后保持稳定,肝胰脏中RNA/DNA的值则在短期下降后有所上升;恢复投喂后,肌肉中RNA/DNA的值除S25组外其余各组均呈上升趋势,而肝胰脏中RNA/DNA的值除C组外其余各组均显著上升(P<0.05)。     

环境因子与基因型及其互作对甜高粱能源品质影响的综合评价

【目的】探讨甜高粱不同基因型的环境适应性及对其能源品质的影响,为发展甜高粱生物能源产业提供参考依据。【方法】以8个不同品种的甜高粱为材料,在内蒙古巴彦淖尔市、山东滨州市和河北黄骅市分别进行田间试验,基于不同品种在不同地区的产量表现,采用方差分析、神经网络模型和主成分分析,研究了环境因子和基因型及其互作对甜高粱能源品质的影响。【结果】(1)供试的8个甜高粱品种在不同地区的产量指标存在差异,这种差异主要是基因型(G)、环境因子(E)及二者互作共同作用的结果,其中环境因子对甜高粱产量的影响最大。(2)土壤有机质对甜高粱茎秆产量、茎秆产糖量及综合产酒量较重要,土壤全盐含量与茎秆汁液糖锤度重要性比值最高,年降雨量为影响甜高粱籽粒产量的重要环境因子,茎秆出汁率主要受无霜期、土壤pH、有机质和碱解氮的影响。(3)品种823、Sart和M81-E在内蒙古巴彦淖尔市综合品质较好,醇甜2号、辽甜1号、能饲1号在山东滨州市综合品质较好,M81-E、能饲杂1、辽甜1号在河北黄骅市综合品质较好。【结论】甜高粱综合能源品质存在品种和地域差异性,发展甜高粱生物能源需因地制宜。     

啤酒大麦蛋白质含量与粒重的品种和环境效应（英文）

研究了浙江省八个大麦主栽品种(秀麦3号、秀92-47、92-11、浙农大3号、浙农大6号、浙农大7号、浙原18、浙皮4号)在六个不同生态地区(杭州、余姚、嘉兴、台州、衢州、丽水)的籽粒蛋白质含量和千粒重.结果表明:不同品种和地区之间,蛋白质含量和千粒重均存在着显著差异,且粒重在地区间的变异要大于蛋白质含量.大麦籽粒蛋白质含量与大于20 ℃的积温和平均日照呈显著正相关,而与平均降雨量无显著相关.根据蛋白质含量和粒重确定了最佳的啤用大麦品种.     

硫酸铵浓度对疏水作用层析纯化重组乙肝表面抗原的影响

以表面抗原活性收率和纯度为考察指标,转化乙肝病毒preS2-S基因重组酵母株,经甘油培养基充分增殖,转移到甲醇培养基中诱导表达.破碎细胞收集细胞原液,离心15000 r·min-1除去细胞碎片,超滤浓缩.结果表明,硫酸铵0.12、0.16 mol·L-1时盐浓度低,HBsAg未结合到疏水介质上;硫酸铵0.24 mol·L-1时疏水性强, HBsAg不宜从介质上洗脱.表明0.20 mol·L-1硫酸铵更适合重组HBsAg纯化.     

乙醇纯化苜蓿叶蛋白效果初探

本文应用有机溶剂法对苜蓿叶蛋白的提取纯化方法进行了比较研究.结果表明:通过85℃直接加热法提取的苜蓿叶蛋白,经乙醇处理提纯后,蛋白提纯率达49.2%,蛋白质含量高达89.4%;苜蓿叶蛋白产品品质明显提高,草青味消失,颜色为浅绿色.