17 results on '"Ouwen, Zhang"'
Search Results
2. Model Prediction Control Path Tracking Algorithm Based on Adaptive Stanley.
- Author
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Qiang Hua, Baoshan Peng, Xiaolin Mou, Ouwen Zhang, Tao He, Li Xia, and Heyan Li
- Published
- 2022
- Full Text
- View/download PDF
3. Research on Energy Consumption Model of Campus Micro-cycle Bus System.
- Author
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Ouwen Zhang, Jinrong Tan, Bian Gong, Qiang Hua, Qi Wang, and Heyan Li
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- 2022
- Full Text
- View/download PDF
4. Promoting and maintaining public participation in waste separation policies — A comparative study in Shanghai, China
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Lishan Xiao, Bo Fu, Tong Lin, Liang Meng, Ouwen Zhang, and Lijie Gao
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Waste separation policy ,Public participation ,System dynamics ,Driving forces ,Environmental Satisfaction ,Environmental sciences ,GE1-350 ,Environmental effects of industries and plants ,TD194-195 - Abstract
Waste management is an evolutionary system, but few studies have explored how and why public willingness to participate in waste separation changes, or explored possible paths to increase residents’ willingness to participate. This paper took Shanghai as a case study of a city that has experienced recent environmental policy change to embrace an evolutionary feedback perspective. The results showed that after the policy implementation, resident’s satisfaction with waste management increased by only 5.3%, and participation willingness actually decreased by 5.4%. A Geodetector model showed that both separation attitude and knowledge are highly important both before and after policy implementation. Residents’ satisfaction with community waste management showed the largest increase soon after the policy implementation while the importance of time occupied by waste separation dropped significantly. Policy simulation by a system dynamics model showed that the community-driven scenario was able to achieve 95% participation 2 years earlier than baseline scenario. Improving community satisfaction by improving waste management infrastructure can offset the adverse effects of an increased number of waste categories. The study helps to quantify the interaction between institutional change and public participation and find effective measures to maintain public participation in environmentally-friendly behaviors.
- Published
- 2023
- Full Text
- View/download PDF
5. Identifying multiple stakeholders’ roles and network in urban waste separation management-a case study in Xiamen, China
- Author
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Lishan, Xiao, Sha, Huang, Zhilong, Ye, Ouwen, Zhang, and Tao, Lin
- Published
- 2021
- Full Text
- View/download PDF
6. Predicting sludge generation patterns and carbon reduction potential under Shared Socioeconomic Pathways
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Ouwen Zhang, Lijie Gao, Weiyue Li, and Lishan Xiao
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Environmental Engineering ,General Medicine ,Management, Monitoring, Policy and Law ,Waste Management and Disposal - Published
- 2022
7. NMR Studies of Unfolded States of an SH3 Domain in Aqueous Solution and Denaturing Conditions
- Author
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Julie D. Forman-Kay and Ouwen Zhang
- Subjects
Models, Molecular ,Protein Denaturation ,Protein Folding ,Magnetic Resonance Spectroscopy ,Protein Conformation ,Hydrochloride ,Molecular Sequence Data ,Peptide ,Guanidines ,Biochemistry ,Protein Structure, Secondary ,SH3 domain ,src Homology Domains ,chemistry.chemical_compound ,Animals ,Drosophila Proteins ,Amino Acid Sequence ,Guanidine ,Dynamic equilibrium ,chemistry.chemical_classification ,Aqueous solution ,Chemistry ,Signal transducing adaptor protein ,Crystallography ,Insect Proteins ,Drosophila ,Protein folding ,Peptides ,Protein Binding - Abstract
The isolated N-terminal SH3 domain of the Drosophila adapter protein drk (drkN SH3 domain) exists in a dynamic equilibrium between a folded (F(exch)) and an unfolded (U(exch)) state under native-like buffer conditions [Zhang, O.,Forman-Kay, J. D. (1995) Biochemistry 34, 6784-6794]. The effect of binding a proline-rich peptide derived from the protein Sos, a biological target of the drkN SH3 domain, on this equilibrium has been investigated. The stabilization of the F(exch) folded state upon binding provides an example of the link between binding and protein folding or stabilization. We have compared NMR parameters of the U(exch) state with those of a denatured state in 2 M guanidine hydrochloride (U(Gdn)). Variable-temperature experiments demonstrate that interactions in a region encompassing residues Gln 23-Leu 28 in the U(exch) state are destabilized upon addition of guanidine hydrochloride. Data from an 15N HSQC-NOESY-HSQC experiment as well as recently developed methods provide more unambiguous structural information than described previously, showing the presence of preferential structure in both unfolded states. Backbone NOEs observed in both unfolded states as well as chemical shifts and coupling constants suggest a rapid equilibrium between extended structure and turn-like structures which may play a role in initiation of protein folding. However, differences in detailed structural features between the two unfolded states argue that caution is needed in interpretation of results from structural characterization of protein conformational states generated using denaturing conditions.
- Published
- 1997
8. [Untitled]
- Author
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Julie D. Forman-Kay, David Shortle, Lewis E. Kay, and Ouwen Zhang
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Crystallography ,Protein structure ,Heteronuclear molecule ,Chemical physics ,Chemistry ,Chemical shift ,Molecule ,Protein folding ,Nuclear Overhauser effect ,Nuclear magnetic resonance spectroscopy ,Biochemistry ,Two-dimensional nuclear magnetic resonance spectroscopy ,Spectroscopy - Abstract
NMR-based structural studies of macromolecules focus to a large extent on the establishmentof interproton distances within the molecule based on the nuclear Overhauser effect (NOE).Despite the improvements in resolution resulting from multidimensional NMR experiments,the detailed characterization of disordered states of proteins or highly overlapped regions offolded molecules using current NMR methods remains challenging. A suite of triple-resonanceNOESY-type pulse schemes is presented which require uniform 15N and 13C labeling andmake use of the chemical shift dispersion of backbone 15N and 13C′ (carbonyl)resonances to increase the spectral resolution. In particular, for the case of partially folded andunfolded proteins, the experiments exploit the fact that the dispersion of 15N and 13C′resonances is comparable to that observed in folded states. Ambiguities that arise in theassignment of NOEs as a result of the severe chemical shift degeneracy in 1H and aliphatic13C nuclei are resolved, therefore, by recording the chemical shifts of 15N or 13C′either before or after the NOE mixing period. Applications of these methods to the study ofthe unfolded state of the N-terminal SH3 domain of drk (drkN SH3) and a partially foldedlarge fragment of staphylococcal nuclease (SNase), Δ131Δ, are presented. Inaddition, an application to folded SNase in complex with the ligands thymidine3′,5′-bisphosphate (pdTp) and Ca2+ is illustrated which allows the assignmentof NOEs between degenerate Hα protons or protons resonating close to water.
- Published
- 1997
9. [Untitled]
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Philip E. Johnson, Lewis E. Kay, D. R. Muhandiram, Lawrence P. McIntosh, Ouwen Zhang, and Daiwen Yang
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chemistry.chemical_classification ,Proton ,Resolution (mass spectrometry) ,Stereochemistry ,Chemical shift ,Sequence (biology) ,Biochemistry ,Amino acid ,chemistry.chemical_compound ,chemistry ,Deuterium ,Amide ,Organic chemistry ,Spin relaxation ,Spectroscopy - Abstract
15 N, 13 C, 2 H-labeled proteins; 2 H spin relaxation; 15 N, NH correlations Summary A triple-resonance pulse scheme is described which records 15 N, NH correlations of residues that immediately follow a methyl-containing amino acid. The experiment makes use of a 15 N, 13 C and fractionally deuterated protein sample and selects for CH2D methyl types. The experiment is thus useful in the early stages of the sequential assignment process as well as for the confirmation of backbone 15 N, NH chemical shift assignments at later stages of data analysis. A simple modification of the sequence also allows the measurement of methyl side-chain dynamics. This is particularly useful for studying side-chain dynamic properties in partially unfolded and unfolded proteins where the resolution of aliphatic carbon and proton chemical shifts is limited compared to that of amide nitrogens.
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- 1997
10. Spectral density function mapping using 15N relaxation data exclusively
- Author
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Attila Szabo, Lewis E. Kay, Neil A. Farrow, Ouwen Zhang, and Dennis A. Torchia
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Larmor precession ,Magnetic Resonance Spectroscopy ,Chemical Phenomena ,Nitrogen Isotopes ,Spectrometer ,Proton ,Chemistry, Physical ,Chemistry ,Relaxation (NMR) ,Analytical chemistry ,Proteins ,Spectral density ,Biochemistry ,src Homology Domains ,Exponential sum ,Correlation function ,Insect Hormones ,Animals ,Drosophila Proteins ,Atomic physics ,Constant (mathematics) ,Spectroscopy - Abstract
A method is presented for the determination of values of the spectral density function, J(omega), describing the dynamics of amide bond vectors from 15N relaxation parameters alone. Assuming that the spectral density is given by the sum of Lorentzian functions, the approach allows values of J(omega) to be obtained at omega = 0, omega N and 0.870 omega H, where omega N and omega H are Larmor frequencies of nitrogen and proton nuclei, respectively, from measurements of 15N T1, T2 and 1H-15N steady-state NOE values at a single spectrometer frequency. Alternatively, when measurements are performed at two different spectrometer frequencies of i and j MHz, J(omega) can be mapped at omega = 0, omega iN, omega jN, 0.870 omega iH and 0.870 omega iH, where omega iN, for example, is the 15N Larmor frequency for a spectrometer operating at 1 MHz. Additionally, measurements made at two different spectrometer frequencies enable contributions to transverse relaxation from motions on millisecond-microsecond time scales to be evaluated and permit assessment of whether a description of the internal dynamics is consistent with a correlation function consisting of a sum of exponentials. No assumptions about the specific form of the spectral density function describing the dynamics of the 15N-NH bond vector are necessary, provided that dJ(omega)/d omega is relatively constant between omega = omega H + omega N to omega = omega H - omega N. Simulations demonstrate that the method is accurate for a wide range of protein motions and correlation times, and experimental data establish the validity of the methodology. Results are presented for a folded and an unfolded form of the N-terminal SH3 domain of the protein drk.
- Published
- 1995
11. A heteronuclear correlation experiment for simultaneous determination of 15N longitudinal decay and chemical exchange rates of systems in slow equilibrium
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Neil A. Farrow, Julie D. Forman-Kay, Ouwen Zhang, and Lewis E. Kay
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Magnetic Resonance Spectroscopy ,Chemical Phenomena ,Nitrogen Isotopes ,Chemistry, Physical ,Chemistry ,Protein dynamics ,Chemical exchange ,Analytical chemistry ,Biochemistry ,Protein Structure, Tertiary ,Water saturation ,Folded form ,Reaction rate constant ,Heteronuclear molecule ,Chemical physics ,Insect Hormones ,Drosophila Proteins ,Molecule ,Protein folding ,Spectroscopy - Abstract
A heteronuclear correlation experiment is described which permits simultaneous characterization of both 15N longitudinal decay rates and slow conformational exchange rates. Data pertaining to the exchange between folded and unfolded forms of an SH3 domain is used to illustrate the technique. Because the unfolded form of the molecule, on average, shows significantly higher NH exchange rates than the folded form, and approach which minimizes the degree of water saturation is employed, enabling the extraction of accurate rate constants.
- Published
- 1994
12. Comprehensive NOE characterization of a partially folded large fragment of staphylococcal nuclease Delta131Delta, using NMR methods with improved resolution
- Author
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David Shortle, Julie D. Forman-Kay, Ouwen Zhang, and Lewis E. Kay
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inorganic chemicals ,Protein Folding ,Magnetic Resonance Spectroscopy ,biology ,Chemistry ,Protein Conformation ,Molecular Sequence Data ,Nuclear magnetic resonance spectroscopy ,SH3 domain ,Peptide Fragments ,Crystallography ,Protein structure ,Structural Biology ,biology.protein ,Peptide bond ,Micrococcal Nuclease ,Protein folding ,Amino Acid Sequence ,Molecular Biology ,Two-dimensional nuclear magnetic resonance spectroscopy ,Heteronuclear single quantum coherence spectroscopy ,Micrococcal nuclease - Abstract
Comprehensive NOE results from detailed structural characterization of a 131 residue partially folded fragment of staphylococcal nuclease (Delta131Delta) made possible by NMR methods with improved resolution are presented. The resulting NOE patterns reflect sampling of both alpha and beta regions of phi, phi conformational space, yet demonstrate significant preferences for both native-like and non-native-like turn and potentially helical conformations. Together with data from studies of the unfolded state of the drkN SH3 domain, NOE patterns observed for partially folded or unfolded proteins are summarized. It is surprising that few long-range NOEs were observed in Delta131Delta. The two longest-range NOEs are both native-like; one of these, an (i,i+5) NOE, provides evidence for a Schellman capping motif for helix termination. Many aliphatic-aliphatic and aliphatic-amide NOEs, which are not normally observed in folded proteins, were detected. We have ruled out significant contributions from spin-diffusion for a number of these NOEs and suggest that one source may be sampling of non-prolyl cis peptide bond configurations in the disordered state of Delta131Delta.
- Published
- 1997
13. Characterization of the backbone dynamics of folded and denatured states of an SH3 domain
- Author
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Lewis E. Kay, Neil A. Farrow, Ouwen Zhang, and Julie D. Forman-Kay
- Subjects
Guanidinium chloride ,Models, Molecular ,Protein Denaturation ,Protein Folding ,Magnetic Resonance Spectroscopy ,Buffers ,Biochemistry ,Guanidines ,SH3 domain ,src Homology Domains ,chemistry.chemical_compound ,Protein structure ,Native state ,Molecule ,Animals ,Drosophila Proteins ,Guanidine ,Sulfates ,Nuclear magnetic resonance spectroscopy ,Protein Structure, Tertiary ,Crystallography ,chemistry ,Insect Hormones ,Protein folding ,Drosophila - Abstract
Measurements of 15N NMR relaxation parameters have been used to characterize the backbone dynamics of folded and denatured states of the N-terminal SH3 domain from the adapter protein drk, in high salt or guanidinium chloride, respectively. Values of the spectral density function evaluated at a number of frequencies are compared. The levels of backbone dynamics in the folded protein show little variation across the molecule and are of similar magnitude to those determined previously for the folded state of the protein in exchange with an unfolded state at low salt concentrations [Farrow et al. (1995) Biochemistry 34, 868-878]. The denatured state of the domain exhibits both more extensive and more heterogeneous dynamics than the folded state. In particular the profile of the spectral density function evaluated at zero-frequency for the unfolded state of the domain indicates that residues in the middle of the protein sequence are considerably less mobile than those at the termini. These data suggest that the molecule is not behaving as an extended polymer and that concerted motions of the central portions of the molecule are occurring, consistent with a reasonably compact conformation in this region. The backbone dynamics of the folded and unfolded states were studied at two temperatures. The level of high-frequency motions in the folded molecule is largely unaffected by changes in temperature, whereas an increase in temperature results in increased high-frequency motion in the unfolded state.
- Published
- 1997
14. Structural, Dynamic, and Folding Studies of SH2 and SH3 Domains
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Julie D. Forman-Kay, Neil A. Farrow, Toshio Yamazaki, Ouwen Zhang, Alex U. Singer, Steven M. Pascal, and Lewis E. Kay
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Folding (chemistry) ,Phosphopeptide ,Chemistry ,Biophysics ,Biomolecular structure ,Nuclear magnetic resonance spectroscopy ,Spectroscopy ,Drosophila Protein ,Random coil ,Proto-oncogene tyrosine-protein kinase Src - Abstract
Recent advances in NMR methodology have made it a powerful approach for the study of biomolecular structure and dynamics (Bax and Grzesiek, 1993; Bax, 1994; Farrow et al., 1994a). In addition to NMR being a structural tool, as a solution spectroscopy it is exquisitely sensitive to dynamic processes - not only fast, low amplitude motions which can often be described by analysis of X-ray crystallographic B factors (Ringe and Petsko, 1985), but also slower, larger amplitude motions. These may include conformational exchange on millisecond time-scales or longer between states as dissimilar as folded and unfolded states of proteins and reflecting motions of tens of angstroms. We have exploited this distinguishing capability of NMR spectroscopy to describe the dynamic processes observed during structural studies of two isolated domains of signal transduction proteins, a Src Homology 2 (SH2) domain of phospholipase Cγ in complex with a phosphopeptide from the platelet-derived growth factor receptor (PDGFR) and an isolated Src Homology 3 (SH3) domain from the drosophila protein Drk1.
- Published
- 1996
15. Structural characterization of folded and unfolded states of an SH3 domain in equilibrium in aqueous buffer
- Author
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Julie D. Forman-Kay and Ouwen Zhang
- Subjects
Protein Denaturation ,Protein Folding ,Magnetic Resonance Spectroscopy ,Chemistry ,Molecular Sequence Data ,Osmolar Concentration ,Hydrogen Bonding ,Nuclear Overhauser effect ,Nuclear magnetic resonance spectroscopy ,Buffers ,Hydrogen-Ion Concentration ,Biochemistry ,SH3 domain ,Peptide Fragments ,Protein Structure, Secondary ,Turn (biochemistry) ,Folding (chemistry) ,Crystallography ,chemistry.chemical_compound ,Protein structure ,Insect Hormones ,Drosophila Proteins ,Protein folding ,Amino Acid Sequence ,Guanidine - Abstract
The isolated N-terminal Src homology 3 (SH3) domain of Drosophila drk exists in equilibrium between folded and unfolded states in aqueous buffer near neutral pH. Nuclear magnetic resonance spectra recorded on both states simultaneously exhibit an approximate 1:1 ratio of protein conformations. The folded form is similar to other known SH3 structures, especially the N-terminal SH3 domain of the mammalian homologue GRB2. A stretch of sequential amide-amide nuclear Overhauser effect cross-peaks for resonances of the unfolded state is observed in a region corresponding to beta-strands in the folded state. The results suggest that turn-like conformations may be preferentially sampled in the folding pathway for this predominantly beta-structured SH3 domain. In addition, a stable turn at Leu-28 is observed in the unfolded but not in the folded state. Comparison of this unfolded form with a denatured state in 2 M guanidine hydrochloride shows that, while both are highly disordered, these states are not identical and more residual structure is present under nondenaturing conditions.
- Published
- 1995
16. Comparison of the backbone dynamics of a folded and an unfolded SH3 domain existing in equilibrium in aqueous buffer
- Author
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Ouwen Zhang, Neil A. Farrow, Julie D. Forman-Kay, and Lewis E. Kay
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Protein Denaturation ,Protein Folding ,Materials science ,Magnetic Resonance Spectroscopy ,Dynamics (mechanics) ,Relaxation (NMR) ,Molecular Sequence Data ,State (functional analysis) ,Biochemistry ,SH3 domain ,Folding (chemistry) ,Drosophila melanogaster ,Aqueous buffer ,Chemical physics ,Insect Hormones ,Peptide bond ,Animals ,Drosophila Proteins ,Amino Acid Sequence ,Neutral ph ,Signal Transduction - Abstract
Two-dimensional NMR 15N relaxation studies have been used to characterize the backbone dynamics and folding transition of the N-terminal SH3 domain of the protein drk (drkN SH3). The isolated drkN SH3 domain exists in equilibrium between a folded and an unfolded state in aqueous buffer and near neutral pH [Zhang et al. (1994) J. Biomol. NMR 4, 845]. The backbone dynamics of both the folded and unfolded states in this exchanging system have been determined and the rates of the folding transition estimated at 14 degrees C. For 12 residues, the values of the spectral density functions of the backbone amide bond vectors at a number of frequencies have been established. Results show that while the unfolded state has considerably greater dynamic behavior, the overall motional properties are consistent with it having a reasonably compact structure in solution. In contrast to the folded state, considerable variations are seen in the values of the spectral densities of the unfolded state as a function of residue number; these variations do not appear to be strongly correlated with structural elements in the folded state. The mean value of the exchange rate associated with the folding transition was determined to be 0.89 s-1, similar to previous measurements of the rate of formation of beta-structure.
- Published
- 1995
17. Backbone 1H and 15N resonance assignments of the N-terminal SH3 domain of drk in folded and unfolded states using enhanced-sensitivity pulsed field gradient NMR techniques
- Author
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J P Olivier, L E Kay, Ouwen Zhang, and J D Forman-Kay
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Magnetic Resonance Spectroscopy ,Chemistry ,Protein Conformation ,Dephasing ,Molecular Sequence Data ,Analytical chemistry ,Resonance ,Nuclear magnetic resonance spectroscopy ,Biochemistry ,Molecular physics ,SH3 domain ,Protein structure ,Insect Hormones ,Dispersion (optics) ,Domain (ring theory) ,Animals ,Drosophila Proteins ,Drosophila ,Amino Acid Sequence ,Pulsed field gradient ,Spectroscopy - Abstract
The backbone 1H and 15N resonances of the N-terminal SH3 domain of the Drosophila signaling adapter protein, drk, have been assigned. This domain is in slow exchange on the NMR timescale between folded and predominantly unfolded states. Data were collected on both states simultaneously, on samples of the SH3 in near physiological buffer exhibiting an approximately 1:1 ratio of the two states. NMR methods which exploit the chemical shift dispersion of the 15N resonances of unfolded states and pulsed field gradient water suppression approaches for avoiding saturation and dephasing of amide protons which rapidly exchange with solvent were utilized for the assignment.
- Published
- 1994
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