Crystallization and preliminary X-ray diffraction study of a protein with a high potential rubredoxin center and a hemerythrin-type Fe center

A newly discovered iron-containing protein, isolated from the bacterium Desulfovibrio vulgaris (Hildenborough, NCIB 8303), has been crystallized. The molecule appears to be a dimer of mass 44kDa. This protein has iron centers with spectrascopic similarities to those in rubredoxins and in hemerythrins. The X-ray diffraction shows symmetry consistent with space group I222 or I212121. Cell parameters are a = 49.2 A, b = 81.3 A, c = 100.1 A, and alpha, beta, gamma = 90 degrees. X-ray diffraction data have been collected to 3.0 A, and a search for useful heavy atom derivatives is in progress for the analysis of the crystal structure of this Fe-protein.     

Isolation and Identification of Gibberellins A4 and A9 from a Fungus Phaeosphaeria sp.

Quinolactacide isolated from Penicillium citrinum F 1539 was synthesized and evaluated for its insecticidal activities. The key steps of the total synthesis were an acyl migration reaction of the enol ester intermediate and dehydrogenation of tetrahydroquinolactacide with manganese dioxide. The synthesized quinolactacide showed 100% and 42% mortality against the green peach aphid (Myzus persicae) and diamondback moth (Plutella xylostella) at 500 ppm, respectively.     

Laboratory evaluation of desiccants and insecticidal soap applied to various substrates to control the deer tick Ixodes scapularis

Abstract. Desiccant and soap pest control products were tested against Ixodes scapularis nymphs on sod, pachysandra, landscaping stones and pinebark wood-chips in a laboratory study. High mortality (91–100%) was obtained with the silica-based desiccant Drione and Safer's insecticidal soap (SIS) treatments except for SIS treated woodchips. SIS and Drione contain 0.2 and 1% pyrethrins, respectively. SIS may be absorbed by the woodchips and not picked up by the nymphs as mortality decreased to 78%. Diatomaceous earth and Dri-die reduced nymphs by only 10–41%; neither desiccant contains insecticides. Nymphal mortality increased 15–17% after 20 or 100 ml of water was sprayed over sod plugs treated with SIS or Drione. The addition of isopropyl alcohol (ROH) to SIS increased the efficacy of SIS against nymphal I. scapularis on treated sod plugs but not on treated landscaping substrates. Drione, SIS, SIS-ROH and chlorpyrifos 50WP treated landscaping stones and pinebark woodchips resulted in 88–95% and 72–96% nymphal mortality, respectively. Unexpectedly, these substrates and treatments affected tick movement as well. Effective pest control products applied to xeric landscaping substrates present in maintained beds and borders near wooded areas could deter tick movement and provide significant levels of tick control.     

Responses of production and storage walnut pests to Bacillus thuringiensis insecticidal crystal protein fragments

Recent advances in genetic engineering have provided the opportunity to induce walnut plants to produce Bacillus thuringiensis Berliner insecticidal crystal protein fragments (ICPFs) for insect control. We studied the effects of two ICPFs CryIA(b) and CrylA(c) previously shown to be encoded by the cryIA(b) and cryIA(c) genes in the B. thuringiensis strains HD-1 and HD-73, respectively. The lethal effects on larvae of codling moth, Cydia pomonella (L.), navel orangeworm, Amyelois transitella (Walker), and the major postharvest pest Indianmeal moth, Plodia interpunctella (Hübner), were investigated. Both proteins were toxic to the three species tested. Indianmeal moth larvae were the most susceptible and navel orangeworm the least; CryIA(b) was generally more toxic to navel orangeworm. Similar relationships resulted when ICPFs were incorporated into the diet. Both ICPFs caused decreased rate of development of navel orangeworm. Effects on pupal weight occurred only at the highest concentration (100 ng/cm²). Neither ICPF affected frequency of mating or fecundity. In addition to the lethal effects, the extended development times observed could have considerable effects on the population dynamics of the navel orangeworm and possibly other species.     

Molecular dynamics simulation of single-walled carbon nanotubes inside liquid crystals

Molecular dynamic simulations of systems of single-walled carbon nanotubes (CNTs) in liquid crystalline solvents were performed, in order to investigate the effect of the molecular structure and phase of the liquid crystal (LC) on the interactions between the CNTs. Three different LC molecules (5CB, 8CB and 5CF) were considered in our study. Our results with 5CB and 8CB suggest that increasing the chain length of the hydrophobic part of the LC molecule by three carbon atoms is insufficient to decrease the tendency for the CNTs to aggregate in the LCs. Additionally, varying the phase of the LC is also insufficient to decrease the aggregation tendency of the CNTs. However, simulations with 5CF (which has fluorine atoms in the head group of the LC molecule) suggest that this LC solvent can decrease the tendency of the CNTs to aggregate. This study is relevant to assist experimentalists with the development of high-quality dispersions of large concentrations of CNTs in the LCs.     

孕烷X受体配体结合结构域蛋白晶体的X线衍射结构解析

目的:利用X线衍射技术解析孕烷X受体(PXR)配体结合结构域(LBD)蛋白晶体的3维结构。方法:对PXR蛋白LBD(130~434氨基酸残基)序列进行密码子优化并化学合成后克隆至pRSFDuet-1表达载体,再将载体导入大肠杆菌BL21(DE3),对PXR-LBD蛋白进行原核表达与分离纯化;采用晶体筛选试剂盒筛选蛋白结晶条件,采用悬滴法获得目标蛋白的晶体;对获得的蛋白晶体进行X线晶体衍射检测,并收集相关数据建立PXR-LBD的三维结构。结果:获得了PXR-LBD的高质量晶体并利用X线衍射解析了该蛋白质晶体的结构数据,使用Phenix.refine软件和COOT软件等对结构进行修正,最终获得了高分辨率的3维结构数据。结论:完成了孕烷X受体配体结合结构域蛋白晶体的X线衍射结构解析,为研究和开发PXR相关药物奠定了基础。     

Modifying bio-catalytic properties of enzymes for efficient biocatalysis: a review from immobilization strategies viewpoint

Enzyme-based catalysis has become one of the most important disciplines in organic synthesis and plays a noteworthy role in the establishment of many chemical industries, e.g. fine chemicals, food or energy, textiles, agricultural, cosmeceutical, medicinal and pharmaceutical industries. However, pristine enzymes fail to demonstrate requisite functionalities for an industrial setting where extremely specific and stable catalysts are required. Immobilization enhances the catalytic stability and activity of enzymes and trims the overall cost burden of the enzyme. Therefore, it widely endeavours for proficient, sustainable, and environmentally responsive catalytic processes. Amongst several immobilization strategies, e.g. (1) supports-assisted, i.e. physical or covalent coupling and (2) supports-free techniques, i.e. cross-linked enzyme crystals (CLECs) or aggregates are the most promising ones and widely pursued for enzyme immobilization purposes. This perspective review focuses on up-to-date developments in the area of enzyme immobilization and presents their potentialities to upgrade and/or modify enzyme properties. Both types of immobilization strategies, i.e. supports-assisted and supports-free techniques are discussed with particular reference to CLECs or aggregates and protein-coated microcrystals. Also, several useful traits achieved after immobilization are also discussed in the second half of the review.     

胆固醇结晶激活动脉粥样硬化斑块巨噬细胞NLRP3炎症体的途径

动脉粥样硬化既是胆固醇在血管壁聚集的疾病,也是发生在动脉壁的一种低强度慢性炎症形式。近年来有研究证实胆固醇结晶在动脉粥样硬化发生发展中具有重要作用。新的显微技术证实,胆固醇结晶在动脉粥样硬化斑块形成的早期即已出现,并与早期炎症有关。胆固醇结晶通过诱发局部炎症,促进大的脂质核心形成;刺破纤维帽,导致斑块破裂进而促进动脉粥样硬化斑块的进展。在影响斑块进程中,NLRP3炎症体的激活对此发挥了重要的作用。NLRP3炎症体是研究最多最明确的炎症体,其与非炎症性疾病的发生发展密切相关。以胆固醇结晶激活NLRP3炎症体的途径作为研究靶点,为动脉粥样硬化的诊断和治疗提供了新的思路和方法。该文就胆固醇结晶在动脉粥样硬化斑块中激活巨噬细胞NLRP3炎症体的两种途径做一综述。     

The chitinase C gene PsChiC from Pseudomonas sp. and its synergistic effects on larvicidal activity

Pseudomonas sp. strain TXG6-1, a chitinolytic gram-negative bacterium, was isolated from a vegetable field in Taixing city, Jiangsu Province, China. In this study, a Pseudomonas chitinase C gene (PsChiC) was isolated from the chromosomal DNA of this bacterium using a pair of specific primers. The PsChiC gene consisted of an open reading frame of 1443 nucleotides and encoded 480 amino acid residues with a calculated molecular mass of 51.66 kDa. The deduced PsChiC amino acid sequence lacked a signal sequence and consisted of a glycoside hydrolase family 18 catalytic domain responsible for chitinase activity, a fibronectin type III-like domain (FLD) and a C-terminal chitin-binding domain (ChBD). The amino acid sequence of PsChiCshowed high sequence homology (> 95%) with chitinase C from Serratia marcescens. SDS-PAGE showed that the molecular mass of chitinase PsChiC was 52 kDa. Chitinase assays revealed that the chitobiosidase and endochitinase activities of PsChiCwere 51.6- and 84.1-fold higher than those of pET30a, respectively. Although PsChiC showed little insecticidal activity towards Spodoptera litura larvae, an insecticidal assay indicated that PsChiC increased the insecticidal toxicity of SpltNPV by 1.78-fold at 192 h and hastened death. These results suggest that PsChiC from Pseudomonas sp. could be useful in improving the pathogenicity of baculoviruses.     

Effective potentials between gold nano crystals – functional dependence on temperature

A method is presented that allows to combine the effective potential between two nano crystals (NC), the potential of mean force (PMF), as obtained from all-atomistic molecular dynamics simulations with perturbation theory. In this way, a functional dependence of the PMF on temperature is derived, which enables the prediction of the PMF in a wide temperature range. We applied the method to systems of capped gold NCs of different size. They show very good agreement with data from atomistic simulations.