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unfolding of Bovine Heart Cytochrome c Induced by Urea and Guanidine Hydrochloride

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Chinese Journal of Chemistry 2011年第4期29卷 813-821页

作者：边六交张潭杨晓燕刘莉郑晓晖 College of Life Science Northwest University Xi'an Shaanxi 710069 China

The unfolding of bovine heart cytochrome c induced by urea and guanidine hydrochloride was studied through their intrinsic fluorescence emission spectra, fluorescence phase diagrams, fluorescence quenching, size-exclusion chromatographies, native polyacrylamide gel electrophoreses and deactivation profiles. The results showed that during their unfolding in urea and guanidine hydrochloride solutions, bovine heart cytochrome c molecules existed only in a unimolecular form and their bi-molecular and/or poly-molecular aggregates and aggregate precipitates were not formed all along. When the urea and guanidine hydrochloride concentrations in denaturation solution were separately about 6.0 and 3.0 mol/L, they could be completely deactivated and almost all of the tryptophan residues originally embedded in the interior of their molecules were exposed to the surface of their molecules. Different from the unfolding of the most often used horse heart cytochrome c, that of bovine heart cytochrome c induced by urea and guanidine hydrochloride was separately a completely co-operative procedure and followed a two-state model.

关键词： bovine heart cytochrome c unfolding denaturants fluorescence spectroscopy electrophoresis

unfolding OF MULTIPARAMETER EQUIVARIANT BIFURCATION PROBLEMS WITH TWO GROUPS OF STATE VARIABLES UNDER LEFT-RIGHT EQUIVALENT GROUP

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Applied Mathematics and Mechanics(English Edition) 2005年第4期26卷 530-538页

作者：郭瑞芝李养成 School of Mathematics and Computing Technology Central South University College of Mathematics and Computer Science Hunan Normal University Changsha 410081 P.R.China

Based on the left_right equivalent relation of smooth map_germs in singularity theory, the unfoldings of multiparameter equivariant bifurcation problems with respect to left_right equivalence are discussed. The state variables of such an equivariant bifurcation problem were divided into two groups, in which the first can vary independently, while the others depend on the first in the varying process. By applying related methods and techniques in the unfolding theory of smooth map_germs, the necessary and sufficient condition for an unfolding of a multiparameter equivariant bifurcation problem with two groups of state variables to be versal is obtained.

关键词： equivariant bifurcation left_right equivalent group unfolding

TAR~*:an improved process similarity measure based on unfolding of Petri nets

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计算机集成制造系统 2012年第8期18卷 1774-1784页

作者： WANG Wen-xing School of Software Tsinghua University Beijing 100084 China Ministry of Education Key Laboratory for Information System Security Tsinghua UniversityBeijing 100084 China~ Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Determining the similarity degree between process models was very important for their management,reuse,and analysis.Current approaches either focused on process model's structural aspect,or had inefficiency or imprecision in behavioral similarity.Aiming at these problems,a novel similarity measure which extended an existing method named Transition Adjacent Relation(TAR) with improved precision and efficiency named TAR * was proposed.The ability of measuring similarity was extended by eliminating the duplicate tasks without impacting the behaviors.For precision,TARs was classified into repeatable and unrepeatable ones to identify whether a TAR was involved in a loop.Two new kinds of TARs were added,one related to the invisible tasks after the source place and before sink place,and the other representing implicit dependencies.For efficiency,all TARs based on unfolding instead of its reach ability graph of a labeled Petri net were calculated to avoid state space explosion.Experiments on artificial and real-world process models showed the effectiveness and efficiency of the proposed method.

关键词： transition adjacent relation unfolding Petri nets behavioral similarity

Improvement of Artificial Foldable Wing Models by Mimicking the unfolding/Folding Mechanism of a Beetle Hind Wing

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Journal of Bionic Engineering 2010年第2期7卷 134-141页

作者： Azhar Muhammad Quoc Viet Nguyen Hoon Cheol Park Do Y.Hwang Doyoung Byun Nam Seo Goo Department of Advanced Technology Fusion Konkuk University National Research Laboratory for Biomimetics and Microsystems Konkuk University Artificial Muscle Research Center Konkuk University Departmenet of Aerospace Engineering Konkuk University

In an attempt to realize a flapping wing micro-air vehicle with morphing wings, we report on improvements to our previousfoldable artificial hind wing.Multiple hinges, which were implemented to mimic the bending zone of a beetle hind wing, weremade of small composite hinge plates and tiny aluminum rivets.The buck-tails of rivets were flared after the hinge plates wereassembled with the rivets so that the folding/unfolding motions could be completed in less time, and the straight shape of theartificial hind wing could be maintained after fabrication.Folding and unfolding actions were triggered by electrically-activatedShape Memory Alloy (SMA) wires.For wing folding, the actuation characteristics of the SMA wire actuator were modifiedthrough heat treatment.Through a series of flapping tests, we confirmed that the artificial wings did not fold back and arbitrarilyfluctuate during the flapping motion.

关键词： hind wing unfolding folding shape memory alloy folding ratio artificial wing

unfolding of C2A Domain of Synaptotagmin I in the Presence of Guanidine Hydrochloride

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Tsinghua Science and Technology 2003年第4期8卷 455-459页

作者：孟凡国惠恩夫周海梦 Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China

The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC). Now this domain represents a large structural family sharing a homologous dimensional structure in many proteins that play important roles in many organisms. The C2A domain is one of the two C2 domains of synaptotagmin I involved in the Ca 2+ regulation of exocytosis. This domain is mostly composed of β sheet except for a small fraction of α helix, and therefore provides an ideal model for a protein folding study. In this report, the unfolding equilibrium of the C2A domain in guanidine hydrochloride (GdnHCl) containing solutions has been studied using ultraviolet (UV) difference spectrum, fluorescence spectrum, size exclusion chromatography (SEC), and circular dichroism (CD) spectrum. The results suggest that unfolding of the C2A domain occurs as a two state process during GdnHCl titration. By examining the changes of both tertiary structure and secondary structure, no intermediates could be detected during this unfolding study. However, it has been found that the native state of the C2A domain has a large hydrophobic surface. This result suggests that as a fragment of a protein, the C2A domain itself may exist in a state with large hydrophobic surface. This hydrophobic surface may be the molecular basis for interaction between domains in the whole protein. Furthermore, the hydrophobic behavior may play a role during the oligomerization of synaptotagmin.

关键词： C2A domain unfolding guanidine hydrochloride (GdnHCl) titration two state reaction

Noise reduction method for nonlinear signal based on maximum variance unfolding and its application to fault diagnosis

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Science China(Technological Sciences) 2010年第8期53卷 2122-2128页

作者： ZHANG Yun &LI BenWei Department of Airborne Vehicle Engineering,Naval Aeronautical Engineering Institute,Yantai 264001,China Department of Airborne Vehicle Engineering Naval Aeronautical Engineering Institute Yantai China

A new noise reduction method for nonlinear signal based on maximum variance unfolding(MVU)is proposed.The noisy sig- nal is firstly embedded into a high-dimensional phase space based on phase space reconstruction theory,and then the manifold learning algorithm MVU is used to perform nonlinear dimensionality reduction on the data of phase space in order to separate low-dimensional manifold representing the attractor from noise subspace.Finally,the noise-reduced signal is obtained through reconstructing the low-dimensional manifold.The simulation results of Lorenz system show that the proposed MVU-based noise reduction method outperforms the KPCA-based method and has the advantages of simple parameter estimation and low parameter sensitivity.The proposed method is applied to fault detection of a vibration signal from rotor-stator of aero engine with slight rubbing fault.The denoised results show that the slight rubbing features overwhelmed by noise can be effectively extracted by the proposed noise reduction method.

关键词： nonlinear noise reduction manifold learning maximum variance unfolding fault diagnosis

Evolution of Conformation and Dynamics of Solvents in Hydration Shell along the Urea-induced unfolding of Ubiquitin

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Chinese Journal of Polymer Science 2019年第7期37卷 708-718页

作者： Ke-Cheng Yang Feng-Chao Cui Ce Shi Wen-Duo Chen Yun-Qi Li Key Laboratory of Synthetic Rubber Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Smart City Research Institute Zhengzhou UniversityZhengzhou 450001China

A clear diagram for the unfolding of protein induced by denaturant is a classical but still unsolved challenge. To explore the unfolded conformations of ubiquitin under different urea concentrations, we performed hybrid Monte Carlo-molecular dynamics simulations (MC-MD) guided by small angle X-ray scattering (SAXS) structural information. Conformational ensembles sampled by the hybrid MC-MD algorithm exhibited typical 3D structures at different urea concentrations. These typical structures suggested that ubiquitin was subjected to a sequential unfolding, where the native contacts between adjacent β-sheets at first were disrupted together with the exposure of hydrophobic core, followed by the conversion of remaining β-strands and helices into random coils. Ubiquitin in 8 mol·L?1 urea is almost a random coil. With the disruption of native structure, urea molecules are enriched at protein hydrated layer to stabilize newly exposed residues. Compared with water, urea molecules prefer to form hydrogen bonds with the backbone of ubiquitin, thus occupying nodes of the hydrogen bonding network that construct the secondary structure of proteins. Meanwhile, we also found that the slow dynamics of urea molecules was almost unchanged while the dynamics of water was accelerated in the hydration shell when more residues were unfolded and exposed. The former was also responsible for the stabilization of unfolded structures.

关键词： Ubiquitin unfolding process Hydration behavior and dynamics Water and urea

Study on the Peptide Chain unfolding of Hydrated Lysozyme by DSC

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Chinese Science Bulletin 1994年第21期39卷 1834-1838页

作者：傅亚珍 Institute of Biophysics. Academia Sinica Beijing 100101.PRC

The interaction between protein and solvent is important in determination of the conformation and stability of natural protein.The first publication of protein structure was based on the thermodynamic rule that hydrop... 详细信息

关键词： hydration lysozymc thermal unfolding DSC.

VERSAL unfolding OF EQUIVARIANT BIFURCATION PROBLEMS IN MORE GENERAL CASE UNDER TWO EQUIVALENT GROUPS

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Acta Mathematica Scientia 2008年第4期28卷 915-923页

作者：李养成何伟 School of Mathematical Science and Computing Technology Central South University

For the unfolding of equivariant bifurcation problems with two types of state variables in the presence of parameter symmetry,the versal unfolding theorem with respect to left-right equivalence is obtained by using the related methods and techniques in the singularity theory of smooth map-germs.The corresponding results in[4,9]can be considered as its special cases.A relationship between the versal unfolding w.***.t.left-right equivalence and the versal deformation w.***.t.contact equivalence is established.

关键词： Equivariant bifurcation problem unfolding left-right equivalence contact equivalence