Crystallization and Preliminary Crystallographic Studies of Luffaculin 1, a Ribosome-inactivating Protein from the Seeds of Luffa Acutangula

1 INTRODUCTION The ribosome-inactivating proteins (RIPs) are RNA N-glycosidases[1, 2] which inactivate ribosomes by cleaving a single N–C glycosidic bond between adenine and ribose at A4324 in the 28s rRNA of rat. Because of the removal of one adenine from rRNA, elongation factorⅡ(EF-2) can not bind to the 60S subunit, so RIPs can arrest protein synthesis. RIPs can be classified into three types based on the struc- tures of genes and mature proteins[3]. Type 1 RIPs with molec…     

The Influence of Ripeness on the Phenolic Content,Antioxidant and Antimicrobial Activities of Pumpkins (Cucurbita moschata Duchesne)

Cucurbita moschata Duchesne (Cucurbitaceae) is a plant food highly appreciated for the content of nutrients and bioactive compounds, including polyphenols and carotenoids, which contribute to its antioxidant and antimicrobial capacities. The purpose of this study was to identify phenolic acids and flavonoids of Cucurbita moschata Duchesne using high-performance liquid chromatography–diode array detection–electrospray ionization tandem mass spectrometry (HPLC–DAD–ESI-MS) at different ripening stages (young, mature, ripened) and determine its antioxidant and antimicrobial activities. According to the results, phenolic acids and flavonoids were dependent on the maturity stage. The mature fruits contain the highest total phenolic and flavonoids contents (97.4 mg GAE. 100 g⁻¹ and 28.6 mg QE. 100 g⁻¹).A total of 33 compounds were identified. Syringic acid was the most abundant compound (37%), followed by cinnamic acid (12%) and protocatechuic acid (11%). Polyphenol extract of the mature fruits showed the highest antioxidant activity when measured by DPPH (0.065 μmol TE/g) and ABTS (0.074 μmol TE/g) assays. In the antimicrobial assay, the second stage of ripening had the highest antibacterial activity. Staphylococcus aureus was the most sensitive strain with an inhibition zone of 12 mm and a MIC of 0.75 mg L⁻¹. The lowest inhibition zone was obtained with Salmonella typhimurium (5 mm), and the MIC value was 10 mg L⁻¹.     

Molecular Replacement Studies of Cucurmosin from Cucurbita Moschata:Structure Homology with Trichosanthin

1 INTRODUCTION Many plants contain proteins that are capable of inactivating ribosomes and therefore are called ribosome-inactivating proteins or RIPs[1]. RIPs are RNA N-glycosidases that inactivate ribosomes through a site-specific deadenylation of the large ribosomal RNA[2, 3]. RIPs are also capable of inactivating many nonribosomal nucleic acid substrates and can be considered as polynucleotide: adenosine glycosidases[4～6]. There are two types of RIPs: type I, single chain pr…     

微流控技术应用于蛋白质结晶的研究*

随着微电子微机械等技术的不断进步,微流控(microfluidics)技术成为目前迅速发展的前沿领域之一,是化学科学和生命科学分析研究的重要技术平台。微流控技术高通量、低消耗和低成本的特点使其在蛋白质结晶条件筛选和优化方面展示了良好的应用前景。本文对应用于蛋白质结晶的各种微流控芯片技术的原理和方法进行了综述,并对目前几种商业化和文献报道的典型蛋白质结晶微流控系统进行了介绍和比较。     

Purification and Crystallization of Flammulin, a Basic Protein with Anti—tumor Activities from Flammulina Velutipes

Flammulin, an anti-tumor protein, was purified from the aqueous extract of basidiomes of Flammulina Velutipes to electrophoretic homogeneity and crystallized by microdialysis against a polyethylene glycol- sodium phosphate buffer. The purified product was found to have marked anti-tumor effects and be able to affect the tumor cells directly.     

高通量蛋白质结晶及其在药物设计中的应用

针对靶标蛋白质的小分子药物研究中,蛋白质的三维结构起到了非常重要的作用.最近高通量蛋白质结晶的快速发展为蛋白质结构的快速确定和药物先导的发现提供了许多新的机会.本文综述了高通量蛋白质结晶及其在新药设计中应用的最新进展。     

基于微流控技术的蛋白质结晶及其筛选方法的研究进展简

微流控技术以其高通量、低消耗和集成化等优点成为蛋白质结晶微型化研究的重要手段. 本文综述了基于微流控技术的蛋白质结晶技术和方法,主要包括微泵微阀、液滴(Droplet)、滑动芯片(SlipChip)以及液滴实验室(DropLab)等技术. 此外,还针对当前膜蛋白在结构生物学研究中的重要地位,综述了应用于膜蛋白结晶的微流控技术的研究进展.     

Primary structure of β-momorcharin,a ribosome-inactivating protein from the seeds of Momordica Charantia Linn (Cucurbitaceae)

The complete amino acid sequence of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae) has been determined. This has been done by the sequence analysis of peptides obtained by enzymatic digestion with trypsin, chymotrypsin and S.aureus V8 protease, as well as by chemical cleavage with BNPS-skatole. The protein consists of 249 amino acid residues containing one asparagine - linked sugar group attached to the site of Asn 51 and has a calculated relative molecular mass of 28,452 Da without addition of the carbohydrate. Comparison of this sequence with those of trichosanthin and other ribosome-inactivating proteins from different species of plants shows a significant homology with each other. Regarding the similarity of their biological properties, an active domain of these proteins has been predicted here.     

基于微流控技术的蛋白质结晶及其筛选方法的研究进展

微流控技术以其高通量、 低消耗和集成化等优点成为蛋白质结晶微型化研究的重要手段. 本文综述了基于微流控技术的蛋白质结晶技术和方法, 主要包括微泵微阀、 液滴(Droplet)、 滑动芯片(SlipChip)以及液滴实验室(DropLab)等技术. 此外, 还针对当前膜蛋白在结构生物学研究中的重要地位, 综述了应用于膜蛋白结晶的微流控技术的研究进展.     

Expression,Purification,Crystallization and Preliminary Crystallographic Analysis of Nucleoside Diphosphate Kinase(NDK) from Aspergillus Flavus

Aspergillus flavus causes serious disease on important agriculture crops, and its secondary metabolic products-aflatoxins are most potent toxin and carcinogen for animal and human. Structural and functional studies of A. flavus proteins may provide insights into the identification of potential therapeutic targets and prevention of damage caused by A. flavus. Here, we report the expression, purification, crystallization and preliminary crystallographic analysis of NDK protein from A. flavus. The NDK protein was expressed in E. coli and purified by using a series of chromatographic methods to 98% purity. The recombinant protein was crystallized and the crystals diffracted to 2.4 ? resolution. The crystal of NDK is in space group of C121 with a = 190.84, b = 169.47, c = 146.94 ?. Preliminary data analysis indicated that the NDK molecule assembles into a multimer in the asymmetric unit.     

豆薯种子中一种具有抗植物病毒活性的蛋白质的初步晶体学研究

从豆科植物豆薯 (Pachyrrhizuserosus,Leguminosae)的种子中分离纯化了一种具有抗植物病毒活性的蛋白质 ,分子量约为 1 5kD。在 2 0 % (w/v)PEG60 0 0 ,0 .1mol/L磷酸盐缓冲液 (pH7.4)条件下得到了可供衍射用的单晶 ,在MarResearchIP上进行了衍射数据收集 ,其衍射能力达 2 .3 。经MarDenzo软件包处理 ,确定其空间群为P2 1 2 1 2 1 ,晶胞参数为 :a =2 8.80 8,b =32 .840 ,c=1 40 .397 。根据Matthews常数估算 ,每个不对称单元含 1个分子。     

Crystallization in the SiO2-Al2O3 System from Amorphous Powders

The crystallization of amorphous chemically homogeneous powders in the SiO₂.Al₂O₃ system has been studied by differential scanning calorimetry and X-ray diffraction. Up to 1300°C only one exotherm has been observed. Only mullite crystallizes for compositions ≤69 mol% Al₂O₃ and spinel for those ≤80%. The crystallizations into mullite and spinel are sharp and exothermic, with an enthalpy of 250–300 J/g. The chemical composition of the crystallized mullite regularly increases from 68 to 76 mol% Al₂O₃ with increasing bulk composition from 60 to 75 mol% Al₂O₃.     

Primary structure of p-momorcharin, a ribosome-inactivating protein from the seeds of Momordica Charantia Linn (Cucurbitaceae)

The complete amino acid sequence of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae) has been determined. This has been done by the sequence analysis of peptides obtained by enzymatic digestion with trypsin, chymotrypsin and S. aureus V8 protease, as well as by chemical cleavage with BNPS-skatole. The protein consists of 249 amino acid residues containing one asparagine - linked sugar group attached to the site of Asn 5 1 and has a calculated relative molecular mass of 28,452 Da without addition of the carbohydrate. Comparison of this sequence with those of trichosanthin and other ribosome-inactivating proteins from different species of plants shows a significant homology with each other. Regarding the similarity of their biological properties, an active domain of these proteins has been predicted here.     

Expression, Purification, Crystallization and Molecular Replacement Studies of TorI, an Inhibition Protein of Tor System

TorI, a Tor system inhibitor acting through protein-protein interaction with the TorR response regulator, is an excisionase that interacts with the integrase and DNA during prophage excision. It has been crystallized by the vapor-diffusion method using polyethylene glycol 3350 as a precipitant at pH 8.5. The X-ray diffraction data sets from the TorI crystal was collected at a resolution of 2.1 , using a synchrotron source. The crystal belongs to primitive monoclinic lattice with cell parameters of 46.210 × 53.992 × 73.561     

基于NMR技术的溶菌酶在琼脂糖凝胶中的动力学研究

运用脉冲梯度场测量自扩散系数及自旋自旋弛豫时间测量核磁共振技术对鸡蛋清溶菌酶(HEWL)在琼脂糖凝胶中的动力学进行了研究.试验结果表明,HEWL在琼脂糖凝胶中的自扩散系数及自旋自旋弛豫时间较其在纯乙酸钠溶液中变小,说明琼脂糖凝胶的三维网状结构使HEWL分子整体运动及局部运动都受到阻碍.并且随着琼脂糖浓度的增大,凝胶网孔尺寸不断减小,HEWL分子运动受限程度加剧,从而蛋白质分子可以较长时间内停留在高浓度区,分子间更容易互相碰撞,发生反应,晶核生长得以促进.同时琼脂糖凝胶较小流体力学网孔尺寸抑制聚晶或沉淀的出现,晶体质量获得提高.     

高岭土合成4A沸石晶化历程

4A沸石是广泛用于催化、污水处理、洗涤剂助剂等领域的一种人工合成沸石分子筛[1,2].采用化学合成法,沸石分子筛是在无定形凝胶和水溶液共存的体系中生成[3].以高岭土为原料,在低温水热条件下进行4A沸石的合成时,由于高岭土并不完全溶解于碱性溶液中,因而这一固液两相体系的反应过程,可能是在偏高岭土无定形的表面上完成.本文通过对合成过程液相成分的变化和固相特征分析,探索了该条件下4A沸石晶核生成及其成长历程.81999-04-19收稿,1999-06-25修回内蒙古自然科学基金资助课题（971302-2）合成原料为n（StQ）：n（AI。O。）一2.06：1的…     

Trichobitacin — a new ribosome-inactivating protein I. The isolation,physicochemical and biological properties of trichobitacin

From the press-residue of the fresh root tuber of Trichosanthes kirilowii Maim (Cucurbitaceae), a new ribosome-inactivating protein (RIP), trichobitacin, was isolated. It has the activity of RNA N-glycosidase and can inhibit the growth of human placental trophoblastic cells. Its molecular weight is 27,228 Da (ES-MS) and pI 9.6. It is a single chain basic RIP. Its amino acid composition was determined. It is a new RIP. It consists of 0.7～0.9% galactose and may be a glycoprotein. Its N- and C-terminal amino acid is Asp and Ala, respectively. Its N-terminal preliminary amino acid sequence has been determined.     

Crystallographic and biophysical analysis of the fusion core from SARS-CoV-2 spike protein

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a newly emerging infectious pathogen causing coronavirus disease 2019 (COVID-19). The virus primarily infects cells via its spike glycoprotein, which is cleaved into S1 and S2 subunits to aid in cell attachment and membrane fusion, respectively. Heptad repeat 1 (HR1) and heptad repeat 2 (HR2) of the S2 subunit are essential for membrane fusion, culminating in an expected six-helix bundle termed fusion core. To better understand the structural and biophysical features of the SARS-CoV-2 fusion core, we designed, constructed, and bacterially produced a recombinant single-chain HR1-L6-HR2 protein and conducted a series of biochemical and biophysical experiments. Our findings demonstrate that the HR1-L6-HR2 protein spontaneously assembles into a highly stable trimeric complex, further confirmed by x-ray crystallographic analysis. The crystal structure of the fusion core reveals a trimeric coiled-coil structure of HR1 antiparallelly surrounded by three HR2 to form a six-helical bundle. Additionally, four residues of HR1 that contribute to binding with HR2 through the formation of hydrogen bonds and salt bridges were observed. These results indicate that the SARS-CoV-2 fusion core exhibits similar characteristics to other class I viral glycoproteins, suggesting potential for drug repurposing as an alternative strategy to combat COVID-19.     

Crystallization Behavior of SiO2-TiO2 Ceramics Derived from Titanosiloxanes on Pyrolysis

The crystallization behavior of SiO2-TiO2 ceramics derived from titanosiloxanes was investigated in relation to the structure of the precursor and the pyrolysis temperature. The titanosiloxanes, [Si(OBut)2OTi(acac) 2O]2, [(ButO)3SiO] 2Ti (OPri)2, and [(ButO)3SiO] 3Ti(OPri), were pyrolyzed in an air atmosphere to form SiO2-TiO2 ceramics which crystallized to anatase at 600–650°C, 700–750°C, and 800–850°C, respectively. The crystallization temperature decreased with increased titanium content of the precursor. The average crystallite size of anatase increased with increased pyrolysis temperature and the titanium content. The crystallization temperature and the crystallite size for SiO2-TiO2 ceramics is controlled by the precursor structure, which may enable control of the physical properties of the ceramic materials.