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Search Results: 1 - 10 of 18212 matches for " Yue-Xiu Si "
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Inhibitory Effect of Phthalic Acid on Tyrosinase: The Mixed-Type Inhibition and Docking Simulations
Shang-Jun Yin,Yue-Xiu Si,Guo-Ying Qian
Enzyme Research , 2011, DOI: 10.4061/2011/294724
Abstract: Tyrosinase inhibition studies are needed due to the medicinal applications such as hyperpigmentation. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics was important. We predicted the 3D structure of tyrosinase, used a docking algorithm to simulate binding between tyrosinase and phthalic acid (PA), and studied the reversible inhibition of tyrosinase by PA. PA inhibited tyrosinase in a mixed-type manner with a =65.84±1.10 mM. Measurements of intrinsic and ANS-binding fluorescences showed that PA induced changes in the active site structure via indirect binding. Simulation was successful (binding energies for Dock6.3=?27.22 and AutoDock4.2=?0.97 kcal/mol), suggesting that PA interacts with LEU73 residue that is predicted commonly by both programs. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors.
Computational Prediction of Protein-Protein Interactions of Human Tyrosinase
Su-Fang Wang,Sangho Oh,Yue-Xiu Si,Zhi-Jiang Wang,Hong-Yan Han,Jinhyuk Lee,Guo-Ying Qian
Enzyme Research , 2012, DOI: 10.1155/2012/192867
Abstract: The various studies on tyrosinase have recently gained the attention of researchers due to their potential application values and the biological functions. In this study, we predicted the 3D structure of human tyrosinase and simulated the protein-protein interactions between tyrosinase and three binding partners, four and half LIM domains 2 (FHL2), cytochrome b-245 alpha polypeptide (CYBA), and RNA-binding motif protein 9 (RBM9). Our interaction simulations showed significant binding energy scores of ?595.3?kcal/mol for FHL2, ?859.1?kcal/mol for CYBA, and ?821.3?kcal/mol for RBM9. We also investigated the residues of each protein facing toward the predicted site of interaction with tyrosinase. Our computational predictions will be useful for elucidating the protein-protein interactions of tyrosinase and studying its binding mechanisms. 1. Introduction Tyrosinase (EC 1.14.18.1) is ubiquitously distributed in organisms and is a critical enzyme involved in melanin production, with multiple catalytic functions in pigment production [1–3]. Tyrosinase mutations are directly linked to pigmentation disorders in mammals [4, 5] and can cause a browning effect in vegetables [6, 7]. In addition, tyrosinase participates in cuticle formation in insects [8, 9]. In mammals, tyrosinase is a bifunctional enzyme that first converts tyrosine to DOPA and then to DOPA quinone, which is further cyclized and oxidized to produce melanin pigments [10]. The human tyrosinase protein contains two Cu2+-binding sites, two cysteine rich regions, a signal peptide region, a transmembrane anchor domain, and an EGF motif [11]. Two Cu2+ ions in the active site of tyrosinase are coordinated by three histidine residues each and are essential for the enzyme’s catalytic activity [12]. Furthermore, the presence of Cu2+ in the active site of tyrosinase is observed across numerous organisms [13]. Therefore, chelation of tyrosinase Cu2+ by synthetic compounds or agents from natural sources has been targeted as a way to block tyrosinase catalysis for medicinal purposes, darkening problems in agricultural products, and cosmetic interests [14, 15]. As the crystallographic structure of tyrosinase has been gradually elucidated, insights into its catalytic mechanisms and active site have also been revealed [16–18]. However, while the catalytic mechanism of tyrosinase-mediated melanin pigment production has been well studied, the relationship between tyrosinase enzyme activity and protein interactions has not been fully elucidated, despite several reports of interacting proteins for tyrosinase [19–22].
Towards -Induced Manganese-Containing Superoxide Dismutase Inactivation and Conformational Changes: An Integrating Study with Docking Simulations
Jiang-Liu Yang,Shang-Jun Yin,Yue-Xiu Si,Zhi-Rong Lü,Xiangrong Shao,Daeui Park,Hae Young Chung,Hai-Meng Zhou,Guo-Ying Qian,Zi-Ping Zhang
Enzyme Research , 2011, DOI: 10.4061/2011/307464
Abstract: Superoxide dismutase (SOD, EC 1.15.1.1) plays an important antioxidant defense role in skins exposed to oxygen. We studied the inhibitory effects of Al3+ on the activity and conformation of manganese-containing SOD (Mn-SOD). Mn-SOD was significantly inactivated by Al3+ in a dose-dependent manner. The kinetic studies showed that Al3+ inactivated Mn-SOD follows the first-order reaction. Al3+ increased the degree of secondary structure of Mn-SOD and also disrupted the tertiary structure of Mn-SOD, which directly resulted in enzyme inactivation. We further simulated the docking between Mn-SOD and Al3+ (binding energy for Dock 6.3: ?14.07?kcal/mol) and suggested that ASP152 and GLU157 residues were predicted to interact with Al3+, which are not located in the Mn-contained active site. Our results provide insight into the inactivation of Mn-SOD during unfolding in the presence of Al3+ and allow us to describe a ligand binding via inhibition kinetics combined with the computational prediction. 1. Introduction Superoxide dismutases (SOD, EC 1.15.1.1) are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide [1–3]. They play an important antioxidant defense role in skins exposed to oxygen. In this regard, for the treatment of systemic inflammatory diseases including skin ulcer lesions, the topical application of free Mn-SOD or Cu, Zn-SOD extracted from bovine, bacterial, and other species was dramatically effective in skin lesions [4]. It has been reported that significant increase in the levels of SOD occurs in vitiligo patients due to the increased oxidative stress [5]. The involvement of oxidative stress in chronic idiopathic urticaria associated with SOD was also reported [6]: the activity of SOD was markedly increased in lesional skin as compared with skin of healthy subjects, indicating that oxidative stress is crucially involved in chronic idiopathic urticaria and suggesting that oxidative stress is secondary to the development of inflammation. The earlier reports [7, 8] suggested that the activity of activator protein-1, which is associated with tumor promotion, was reduced in Mn-SOD transgenic mice overexpressing Mn-SOD in the skin, suggesting that Mn-SOD reduced tumor incidence by suppressing activator protein-1 activation. The mechanism of Mn-SOD catalysis is very important, and the mechanism therefore needs to be investigated from different sources using various kinetic methods. The information regarding the tertiary structure and the structural integrity of the active site of Mn-SOD is little known and in
Effect of recombinant plasmid of Helicobacter pylori ureB gene on gastric epithelial cell
幽门螺杆菌ureB基因转染胃上皮细胞及其对细胞的作用

ZHANG Jing SHE Fei-fei,CHEN Yue-xiu CHEN Hao,
张静
,佘菲菲,陈月秀,陈豪

微生物学报 , 2005,
Abstract: To investigate the effect of recombinant plasmid of Helicobacter pylori ureB gene on gastric epithelial cell. The full length sequence of ureB gene from NCTC11637 was amplified by PCR. The recombinant plasmid was constructed by cloning the open reading frame (ORF) of ureB into the eukaryotic expression vector pcDNA3.1, and was transfected SGC-7901 cells, then the clones resisting Hygromacine were screened. mRNA expression of ureB of transfected cells was detected by RT-PCR.The effect of recombinant plasmid of Hp ureB gene on cell phenotype was observed by fluorescence strain, on proliferation by MTT, on apoptosis and cell cycles by flow cytometry, respectively. The positive clones of ureB(SureB) appeared cell membrane budding and cell shrinkage. MTT assay showed there was no statistic significance between the SureB and SpcDNA3.1 which were transfected only by pcDNA3.1 (P>0.05), suggesting that the growth of SureB were not inhibited. The apoptosis rate of SureB was higher than that of SpcDNA3.1(P=0.007). Analysis for cell cycle showed that in SureB cells the proportion of S phase increased, the proportion of both G 2/M and G 0/G 1 phase decreased. Positive transfection of ureB gene into SGC-7901 can change cell phenotype and induce cell apoptosis.
Driving Forces of Fertilizer Consumption in China (Ⅱ Planting Structure)
中国化肥消费需求影响因素及走势分析(Ⅱ)

ZHANG Wei-feng,JI Yue-xiu,MA Ji,WANG Yan-feng,MA Wen-qi,ZHANG Fu-suo,
张卫峰
,季玥秀,马骥,王雁峰,马文奇,张福锁

资源科学 , 2008,
Abstract: Based on the data from farm household survey, the fertilizer consumption of different crops in terms of rate and area of fertilizer application was assessed, and the allocation of fertilizers for different crops was estimated based on both the household survey data and statistic data in 2005. The effectiveness of cropping pattern change on fertilizer consumption was analyzed through multiple regression models. The results show that all of the crops were fertilized with huge quantity of fertilizers, and the rate and area of fertilizer application are relatively higher for N and P2O5, but relatively lower for K2O. The cropping area of applying N and P2O5 and K2O take up 87 %, 66 % and 43 % respectively. The N fertilizer application for most crops exceeds 100kg per hectare. The P2O5 application for most of crops exceeds 80 kg per hectare. The application rate of K2O is always lower than that of N and P2O5. The application rate of N and P2O5 in China are higher than that in other countries. The cash crops are the main contributor to the increased fertilizer consumption in China. The area of grain crops accounted for 63 % of the national total, and the share of total fertilizer consumption of grain crops decreased to 46% in 2005 from 80% in 1980. The total fertilizer consumption and nitrogen fertilizer consumption are sensitive to the changes of growing area of rice, potato, maize, oilseeds, vegetables and fruit tree. The growing area changes of rice, oilseeds, cotton, sugar beet, vegetable and fruit tree are main factors affecting phosphate fertilizer consumption. The growing area change of rice and some cash corps affect the consumption of potash fertilizer. It is predicted that the area of grain crop will keep stable and growing area of cash crops with huge fertilizer consumption will increase continuously in the future. Therefore, the national fertilizer consumption will increase along with the increased area of cash crops. Especially, there is a big room for increase of Potassium fertilizer application.
An Analysis on Driving Force of Fertilizer Demand of China Ⅲ Population, Economy, Technology and Policy
中国化肥消费需求影响因素及走势分析Ⅲ人口、经济、技术、政策

ZHANG Wei-feng,JI Yue-xiu,MA Ji,WANG Yan-feng,MA Wen-qi,ZHANG Fu-suo,
张卫峰
,季玥秀,马骥,王雁峰,马文奇,张福锁

资源科学 , 2008,
Abstract: 从人口、国民经济、农业经济、生产技术及政策角度分析了中国及世界上一些典型国家化肥消费和这些因素的关系。从化肥消费强度和消费系数角度深入分析了各个国家发展的特点。结果表明世界主要国家化肥消费都随人口增长速率的增加而增长,反映出人民基本粮食和营养需求对化肥需求具有促进作用。同时随着国民经济发展,化肥应用领域已经扩展到化工、渔业、林业、牧业等多个领域,我国传统农田使用比例已下降到85%。各个国家农业经济发展中的化肥养分资源利用效率差异巨大,发达国家已走上集约化可持续发展的道路,每万元农业GDP的化肥消费已降至lt纯养分,而发展中国家尤其是中国的强度仍高于2t纯养分,且磷肥和钾肥的需求还在增长。从弹性系数来看,我国农业经济发展与化肥需求仍呈等比例增长关系,说明农业经济对化肥过度依赖,其原因是技术发展较慢,单位养分的生产力水平和整个国家的养分再利用水平太低。但从欧美的经验来看,中国提高技术水平、转变资源利用效率的空间很大,而且在不长的时期内完全有可能实现,但取决于政策因素的转变。
Factors Affecting Fertilizer Demand and Supply in China
中国化肥消费需求影响因素及走势分析——Ⅰ化肥供应

ZHANG Wei-feng,JI Yue-xiu,MA Ji,WANG Yan-feng,MA Wen-qi,ZHANG Fu-suo,
张卫峰
,季玥秀,马骥,王雁峰,马文奇,张福锁

资源科学 , 2007,
Abstract: The consumption of chemical fertilizer has five characters.The fertilizer demands is driven by the food demand with the population growth,can be replaced by other materials,independent on agricultural planting structure,affected by agricultural technology and varies in different countries.Multiple characters determine various factors that can affect its demand,in which the supply is the most important factor.This feature has been witnessed obviously in China. The fertilizer consumption in China was constrained by fertilizer supply since the funding of the people's republic of China in 1949.The weak resources base and outdated technology of fertilizer industry in China resulted in the insufficient supply and low-level consumption until the 1990s.In recent years,with the development of exploitation of resources and improvement of manufacturing technology,the fertilizer output and product structure have changed significantly.The self-sufficient nitrogen fertilizer has exceeded 100% and that of phosphate fertilizer got 94% in 2005.More and more categories of fertilizers,which are difficult to be decomposed such as ABC and SSP have been replaced by prone-decomposed ones such as Urea and Di-Ammonium Phosphate.The fertilizer consumption has increased greatly accompanied by the industrial development.It is forecasted that,in the next years,the fertilizer supply would be decided by demand,and the unbalanced supply and demand situation in different regions will emerge and would aggravate when the raw materials for fertilizer production are depleted and their prices are growing higher.It is proved the duration of some key raw materials are lower than 50 years in which the high grade phosphate rock can only be used in next ten years.It is forecasted that the fertilizer industry would be transferred to some regions with abundant natural resources,and more than 50% of the provinces are short of fertilizer supply.And the fertilizer products structure would be changed further from difficult decomposed ones to prone decomposed ones.It is forecasted that the increase of production of N,P2O5 and K2O would be 6,3 and 1 million tones respectively from 2006 to 2010.All of the changes would induce the further changes on fertilizer consumption.Although the price of fertilizer has been growing in recent years,the price flexibility decreased to less than 1 that means the fertilizer demand is inelastic to the changes of fertilizer price.In a word,the effectiveness of fertilizer supply in fertilizer consumption is becoming feeble.Therefore,we should to improve the fertilizer industry by using fertilizer reasonably in the future.
IMPROVEMENT OF CONFINEMENT BY LOWER HYBRID WAVES
利用低杂波改善约束的实验研究

LI JIAN-GANG LUO,JIA-RONG,WAN BAO-NIAN,LIU YUE-XIU,GONG XIAN-ZU,LI DUO-CHUAN,JIE YIN-XIAN,LI ZHI-XIU,XU XIANG-DONG,
李建刚
,罗家融,万宝年,刘岳修,龚先祖,李多传,揭银先,李智秀,徐旵东

物理学报 , 2000,
Abstract: Quasi-steady-state H-mode has been achieved by combination of two lower hybrid w aves in HT-6M tokamak.Plasma energy confinement time increases by two times,and the particle confinement time increases by a factor of three under a high plasma density condition.The wave diffusion and current radial diffusion code is used to simulate the experimental data on HT-6M.The calculated results show that the off-axis power deposition of lower hybrid wave is formed due to the low toroidal magnetic field and high plasma density.Reversed sheared(RS) configuration of th e plasma current density is formed during H-mode phase.The RS configuration and internal transport barrier are attributed to the enhanced confinement improvemen t.The experimental data also gives the evidence for the reversed shear formation .
Simulation of lower hybrid current drive
低杂波电流驱动的数值模拟

Ding Bo-Jiang,Kuang Guang-Li,Liu Yue-Xiu,Shen Wei-Ci,Yu Jia-Wen,Shi Yao-Jiang,
丁伯江
,匡光力,刘岳修,沈慰慈,俞家文,石跃江

物理学报 , 2002,
Abstract: Resolving the two dimensional Fokker Planck equation, evolutions of the driven current and its profile on HT 7 tokamak are obtained. The simulated results are nearly in agreement with the experimental data, which supplies a theoretical guidance for lower hybrid current drive (LHCD) experiments on HT 7 tokamak. In addition, the effect of radial diffusion of fast electrons on the driven current during LHCD is considered by means of solving the current diffusion equation.
Explicit demonstration of nonabelian anyon, braiding matrix and fusion rules in the Kitaev-type spin honeycomb lattice models
Yue Yu,Tieyan Si
Physics , 2008,
Abstract: The exact solubility of the Kitaev-type spin honeycomb lattice model was proved by means of a Majorana fermion representation or a Jordan-Wigner transformation while the explicit form of the anyon in terms of Pauli matrices became not transparent. The nonabelian statistics of anyons and the fusion rules can only be expressed in indirect ways to Pauli matrices. We convert the ground state and anyonic excitations back to the forms of Pauli matrices and explicitly demonstrate the nonabelian anyonic statistics as well as the fusion rules. These results may instruct the experimental realization of the nonabelian anyons. We suggest a proof-in-principle experiment to verify the existence of the nonabelian anyons in nature.
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