@article {2649, title = {Free Energy Barrier Estimation for the Dissociation of Charged Protein Complexes in the Gas Phase}, journal = {Journal of Physical Chemistry A}, volume = {113}, number = {16}, year = {2009}, note = {ISI Document Delivery No.: 435ZUTimes Cited: 4Cited Reference Count: 29Wanasundara, Surajith N. Thachuk, Mark}, month = {Apr}, pages = {3814-3821}, type = {Article}, abstract = {Free energies are calculated for the protonated cytochrome c{\textquoteright} dimer ion in the gas phase as a function of the center of mass distance between the monomers. A number of different charge partitionings are examined as well as the behavior of the neutral complex. It is found that monomer unfolding competes with complex dissociation and that the relative importance of these two factors depends upon the charge partitioning in the complex. Symmetric charge partitionings preferentially suppress the dissociation barrier relative to unfolding, and complexes tend to dissociate promptly with little structural changes occurring in the monomers. Alternatively, asymmetric charge partitionings preferentially lower the barrier for monomer unfolding relative to the dissociation barrier. In this case, the monomer with the higher charge unfolds before the complex dissociates. For the homodimer considered here, this pathway has a large free energy barrier. The results can be rationalized using schematic two-dimensional free energy surfaces. Additionally, for large multimeric complexes, it is argued that the unfolding and subsequent charging of a single monomer is a favorable process, cooperatively lowering both the unfolding and dissociation barriers at the same time.}, keywords = {ASSEMBLIES, ELECTROSPRAY-IONIZATION, MASS-SPECTROMETRY, MODEL, MOLECULAR-DYNAMICS, ORIGIN, PATHWAYS, SIMULATIONS, SYSTEMS, THERMAL-DISSOCIATION}, isbn = {1089-5639}, url = {://000265383200014}, author = {Wanasundara, S. N. and Thachuk, M.} } @article {2050, title = {Adsorption and Structure of Water on Kaolinite Surfaces: Possible Insight into lee Nucleation from Grand Canonical Monte Carlo Calculations}, journal = {Journal of Physical Chemistry A}, volume = {112}, number = {43}, year = {2008}, note = {ISI Document Delivery No.: 364TGTimes Cited: 6Cited Reference Count: 29Croteau, T. Bertram, A. K. Patey, G. N.}, month = {Oct}, pages = {10708-10712}, type = {Article}, abstract = {Grand canonical Monte Carlo calculations are used to determine water adsorption and structure on defect-free kaolinite surfaces as a function of relative humidity at 235 K. This information is then used to gain insight into ice nucleation on kaolinite surfaces. Results for both the SPC/E and TIP5P-E water models are compared and demonstrate that the Al-surface [(001) plane] and both protonated and unprotonated edges [(100) plane] strongly adsorb at atmospherically relevant relative humidities. Adsorption on the Al-surface exhibits properties of a first-order process with evidence of collective behavior, whereas adsorption on the edges is essentially continuous and appears dominated by strong water lattice interactions. For the protonated and unprotonated edges no structure that matches hexagonal ice is observed. For the Al-surface some of the water molecules formed hexagonal rings. However, the a. lattice parameter for these rings is significantly different from the corresponding constant for hexagonal ice (Ih). A misfit strain of 14.0\% is calculated between the hexagonal pattern of water adsorbed on the Al-surface and the basal plane of ice Ih. Hence, the ring structures that form on the Al-surface are not expected to be good building-blocks for ice nucleation due to the large misfit strain.}, keywords = {AEROSOL-PARTICLES, ice, IMPACT, LAYER, models, N2O5, SIMULATIONS, SYSTEMS, VAPOR}, isbn = {1089-5639}, url = {://000260357600002}, author = {Croteau, T. and Bertram, A. K. and Patey, G. N.} } @article {2218, title = {Hydrophobic interactions in urea - Trimethylamine-N-oxide solutions}, journal = {Journal of Physical Chemistry B}, volume = {112}, number = {35}, year = {2008}, note = {ISI Document Delivery No.: 342RDTimes Cited: 2Cited Reference Count: 25Paul, Sandip Patey, G. N.}, month = {Sep}, pages = {11106-11111}, type = {Article}, abstract = {The influence of osmolytes urea and trimethylemine-N-oxide (TMAO) on hydrophobic interactions is investigated employing molecular dynamics simulations. These osmolytes are of interest because of their opposing influence on proteins in solution; the denaturing effect of urea can be countered with TMAO. A neopentane pair is used to model typical nonpolar entities. Binary water-urea and water-TMAO as well as ternary water-urea-TMAO systems are considered. Neopentane-neopentane potentials of mean force, neopentane-water, and neopentane-osmolyte distribution functions are reported. Urea is found to have only modest influence on the neopentane-neopentane potential of mean force, but the hydrophobic attraction is completely destroyed by the presence of TMAO. It is shown that TMAO tends to act as a simple "surfactant" displacing water and urea (if it is present) from the first solvation shell of neopentane. It is likely the surfactant-like influence of TMAO that accounts for the elimination of the hydrophobic attraction. The implications of Our results for explanations of the action of TMAO in protein solutions are discussed.}, keywords = {AQUEOUS UREA, FORCE, MOLECULAR-DYNAMICS, OSMOLYTES, POTENTIALS, PROTEIN DENATURATION, SIMULATIONS, WATER}, isbn = {1520-6106}, url = {://000258800300046}, author = {Paul, S. and Patey, G. N.} } @article {2034, title = {Single molecule force spectroscopy reveals engineered metal chelation is a general approach to enhance mechanical stability of proteins}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, number = {32}, year = {2008}, note = {ISI Document Delivery No.: 339EKTimes Cited: 16Cited Reference Count: 44Cao, Yi Yoo, Teri Li, Hongbin}, month = {Aug}, pages = {11152-11157}, type = {Article}, abstract = {Significant mechanical stability is an essential feature shared by many elastomeric proteins, which function as molecular springs in a wide variety of biological machinery and biomaterials of superb mechanical properties. Despite the progress in understanding molecular determinants of mechanical stability, it remains challenging to rationally enhance the mechanical stability of proteins. Using single molecule force spectroscopy and protein engineering techniques, we demonstrate that engineered bi-histidine metal chelation can enhance the mechanical stability of proteins significantly and reversibly. Based on simple thermodynamic cycle analysis, we engineered a bi-histidine metal chelation site into various locations of the small protein, GB1, to achieve preferential stabilization of the native state over the mechanical unfolding transition state of GB1 through the binding of metal ions. Our results demonstrate that the metal chelation can enhance the mechanical stability of GB1 by as much as 100 pN. Since bi-histidine metal chelation sites can be easily implemented, engineered metal chelation provides a general methodology to enhance the mechanical stability of a wide variety of proteins. This general approach in protein mechanics will enable the rational tuning of the mechanical stability of proteins. It will not only open new avenues toward engineering proteins of tailored nanomechanical properties, but also provide new approaches to systematically map the mechanical unfolding pathway of proteins.}, keywords = {BINDING SITES, charge, DESIGN, DOMAINS, ELASTICITY, engineering, EXTRACELLULAR-MATRIX PROTEIN, mechanical unfolding, PROTEIN, protein mechanics, rational design, SIMULATIONS, STABILIZATION, STRENGTH, THERMOSTABILITY, TITIN}, isbn = {0027-8424}, url = {://000258560700024}, author = {Cao, Y. and Yoo, T. and Li, H. B.} } @article {728, title = {Identification and interpretation of generalized two-dimensional correlation spectroscopy features through decomposition of the perturbation domain}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 8Cited Reference Count: 33}, month = {Dec}, pages = {1561-1574}, type = {Article}, abstract = {Generalized two-dimensional correlation spectroscopy offers great scope for revealing the behavior of relationships between components of a system under empirical study. We have developed methods that aid in the interpretation of two-dimensional correlation spectroscopy. These methods include reference patterns for two-dimensional correlation and correlation coefficient maps, their superposition and joint interpretation, and the use of delta functions to decompose them in the perturbation domain. We show how their joint use permits discrimination between similar two-dimensional correlation map features on the basis of different correlation coefficients. We also show how the decomposition of maps into the perturbation domain reflects the dynamic behavior of spectral features over the course of the perturbation and permits discrimination between otherwise highly similar two-dimensional correlation crosspeaks. These approaches simplify the interpretation of two-dimensional correlation spectroscopy maps and facilitate access to their rich information content.}, keywords = {coefficient maps, COMPONENT ANALYSIS, correlation, FT-IR SPECTROSCOPY, INFRARED CORRELATION SPECTROSCOPY, INTENSITY CHANGES, MONOLAYER FILMS, perturbation domain decomposition, RAMAN-SPECTRA, reference patterns, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SIMULATIONS, SPECTRA, trajectory peaks, two-dimensional correlation spectra}, isbn = {0003-7028}, url = {://000187234800014}, author = {Schulze, G. and Jirasek, A. and Blades, M. W. and Turner, R. F. B.} } @article {728, title = {Identification and interpretation of generalized two-dimensional correlation spectroscopy features through decomposition of the perturbation domain}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 8Cited Reference Count: 33}, month = {Dec}, pages = {1561-1574}, type = {Article}, abstract = {Generalized two-dimensional correlation spectroscopy offers great scope for revealing the behavior of relationships between components of a system under empirical study. We have developed methods that aid in the interpretation of two-dimensional correlation spectroscopy. These methods include reference patterns for two-dimensional correlation and correlation coefficient maps, their superposition and joint interpretation, and the use of delta functions to decompose them in the perturbation domain. We show how their joint use permits discrimination between similar two-dimensional correlation map features on the basis of different correlation coefficients. We also show how the decomposition of maps into the perturbation domain reflects the dynamic behavior of spectral features over the course of the perturbation and permits discrimination between otherwise highly similar two-dimensional correlation crosspeaks. These approaches simplify the interpretation of two-dimensional correlation spectroscopy maps and facilitate access to their rich information content.}, keywords = {coefficient maps, COMPONENT ANALYSIS, correlation, FT-IR SPECTROSCOPY, INFRARED CORRELATION SPECTROSCOPY, INTENSITY CHANGES, MONOLAYER FILMS, perturbation domain decomposition, RAMAN-SPECTRA, reference patterns, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SIMULATIONS, SPECTRA, trajectory peaks, two-dimensional correlation spectra}, isbn = {0003-7028}, url = {://000187234800014}, author = {Schulze, G. and Jirasek, A. and Blades, M. W. and Turner, R. F. B.} } @article {602, title = {Liquid-vapor criticality in a fluid of charged hard dumbbells}, journal = {Journal of Chemical Physics}, volume = {119}, number = {15}, year = {2003}, note = {ISI Document Delivery No.: 728EKTimes Cited: 9Cited Reference Count: 55}, month = {Oct}, pages = {7952-7956}, type = {Article}, abstract = {The vapor-liquid criticality of a fluid of charged hard dumbbells is investigated employing grand canonical Monte Carlo simulations and mixed-field finite-size scaling methods. The reduced critical temperature and density obtained are T-c(*)=0.04911+/-0.00003 and rho(c)(*)=0.101+/-0.003, respectively. The critical temperature is very close to that of the restricted primitive model (RPM) for ionic fluids, while the critical density is similar to25\% larger than that of the RPM. The "fits" to the Ising ordering operator distribution are good, and are of similar quality to those found for the RPM with systems of comparable size. However, for the finite-size systems simulated, the constant volume heat capacity, C-V, gives no indication of an Ising-type "divergence" at T-c. This is analogous to the RPM, and serves to demonstrate that this still puzzling behavior is not restricted to that model. (C) 2003 American Institute of Physics.}, keywords = {COEXISTENCE-CURVE, CRITICAL EXPONENT, CRITICAL PARAMETERS, CRITICAL-BEHAVIOR, HEAT-CAPACITY, IONIC BINARY-MIXTURE, LENNARD-JONES FLUID, LONG-RANGE INTERACTIONS, MONTE-CARLO, RESTRICTED PRIMITIVE MODEL, SIMULATIONS}, isbn = {0021-9606}, url = {://000185703100037}, author = {Daub, C. D. and Patey, G. N. and Camp, P. J.} } @article {450, title = {Structural investigation of Silicalite-I loaded with n-hexane by X-ray diffraction, Si-29 MAS NMR, and molecular modeling}, journal = {Chemistry of Materials}, volume = {14}, number = {5}, year = {2002}, note = {ISI Document Delivery No.: 555JCTimes Cited: 23Cited Reference Count: 25}, month = {May}, pages = {2192-2198}, type = {Article}, abstract = {{The room temperature (298 K) structure of zeolite Silicalite-I loaded with approximately eight n-hexane molecules per unit cell was solved from twinned single-crystal X-ray diffraction (XRD) data in the monoclinic space group P12(1)/n1 with a = 19.8247(2) Angstrom}, keywords = {ADSORPTION, ALKANES, ENERGY-MINIMIZATION CALCULATIONS, LOCALIZATION, NAPHTHALENE, ORTHORHOMBIC FRAMEWORK, POWDER DIFFRACTION, SIMULATIONS, ZEOLITE H-ZSM-5, ZSM-5}, isbn = {0897-4756}, url = {://000175790100041}, author = {Morell, H. and Angermund, K. and Lewis, A. R. and Brouwer, D. H. and Fyfe, C. A. and Gies, H.} } @article {4630, title = {Forces between like-charged plates in electrolyte solution: Ion-solvent packing versus electrostatic effects}, journal = {Physical Review E}, volume = {60}, number = {4}, year = {1999}, note = {ISI Document Delivery No.: 250XETimes Cited: 12Cited Reference Count: 19Part B}, month = {Oct}, pages = {4416-4422}, type = {Article}, abstract = {The anisotropic hypernetted-chain approximation is solved numerically for mixtures of neutral hard-sphere solvent particles and divalent counterions between charged plates. A detailed analysis of the different components of force acting between the plates is given. At separations of a few solvent diameters, it is shown that even at relatively high surface charge and moderate solvent density, the ionic contribution to the force tends to be dominated by the hard-core or packing component. If the ions and solvent particles are of equal size, then the net pressure between the plates can be reasonably well approximated by adding the pressures of pure one-component ionic and solvent systems. However, if the ion and solvent diameters are significantly different the pressure curve is more complex, and the simple superposition of the ionic and solvent pressures no longer works. For this case, we show that to a good approximation it is still possible to divide the pressure into electrostatic and hard-core components, but now the appropriate hard-core system must itself be a mixture of neutral hard spheres. [S1063-651X(99)08210-0].}, keywords = {ELECTRICAL DOUBLE-LAYER, IMAGE, INHOMOGENEOUS COULOMB FLUIDS, interactions, MOLECULAR THEORY, NARROW SLITS, PLANAR SURFACES, SIMULATIONS, SOLVATION FORCES}, isbn = {1063-651X}, url = {://000083414900025}, author = {Otto, F. and Patey, G. N.} } @article {3939, title = {Ion solvation dynamics in binary mixtures}, journal = {Journal of Chemical Physics}, volume = {106}, number = {7}, year = {1997}, note = {ISI Document Delivery No.: WH024Times Cited: 37Cited Reference Count: 21}, month = {Feb}, pages = {2782-2791}, type = {Article}, abstract = {The dynamics of selective ion solvation in binary Stockmayer solvents is investigated using molecular dynamics simulations. The dependence of the usual solvation response function, S(t), on solvent composition and on the relative polarity of the solvent species is examined and discussed. We also introduce particle solvation response functions which describe the compositional relaxation of the first solvation shell. It is shown that the selective solvation process can be well described by a simple phenomenological model based on the ideas of elementary chemical kinetics. This model is useful and helps in the identification of two distinct time scales present in the selective solvation process. These are associated with a rapid electrostriction step during which the total number of particles in the first shell increases to its equilibrium value, and a slower spatial redistribution process during which the composition of the first shell achieves equilibrium. The redistribution phase depends on the rate of mutual ion-solvent diffusion and also on the rate of particle exchange between the first and second shells. A detailed analysis of the exchange process indicates that exchanges occur on virtually a one-to-one basis with the insertion of a stronger dipole into the first shell being mirrored by an almost immediate ejection of a weaker one. (C) 1997 American Institute of Physics.}, keywords = {DIPOLAR LIQUIDS, ELECTRON-TRANSFER, METHANOL, SIMULATIONS}, isbn = {0021-9606}, url = {://A1997WH02400027}, author = {Day, T. J. F. and Patey, G. N.} } @article {2982, title = {SOLVATION DYNAMICS IN ELECTROLYTE-SOLUTIONS}, journal = {Journal of Chemical Physics}, volume = {100}, number = {2}, year = {1994}, note = {ISI Document Delivery No.: MT007Times Cited: 33Cited Reference Count: 40}, month = {Jan}, pages = {1552-1558}, type = {Article}, abstract = {A microscopic theory of the dynamics of ion solvation in electrolyte solutions is given. Consistent with the pure solvent case, the theory predicts a very fast and important inertial relaxation at short times. This is followed by oscillations and an extremely slow long-time decay associated with the formation of an equilibrium {\textquoteright}{\textquoteright}ion atmosphere{\textquoteright}{\textquoteright} about the newly charged particle.}, keywords = {DIELECTRIC-RELAXATION, INVARIANT EXPANSION, ION, LIQUIDS, MEAN SPHERICAL MODEL, ORNSTEIN-ZERNIKE EQUATION, SIMULATIONS, SOLVENT, SPHERES}, isbn = {0021-9606}, url = {://A1994MT00700085}, author = {Chandra, A. and Patey, G. N.} } @article {2993, title = {STRUCTURE OF 2-COMPONENT CLUSTERS}, journal = {Journal of Chemical Physics}, volume = {101}, number = {3}, year = {1994}, note = {ISI Document Delivery No.: NY002Times Cited: 43Cited Reference Count: 17}, month = {Aug}, pages = {2432-2445}, type = {Article}, abstract = {{Phase separation in binary liquid Lennard-Jones clusters is investigated employing computer simulation methods. Clusters ranging in size from 50 to 240 particles are considered with special emphasis on systems with equal numbers of A and B particles. Cluster morphology is systematically explored by varying the ratios}, keywords = {MOLECULAR-DYNAMICS, SIMULATIONS, TRANSITION}, isbn = {0021-9606}, url = {://A1994NY00200071}, author = {Clarke, A. S. and Kapral, R. and Patey, G. N.} }