G. P. Petrova

The ONIOM Method and Its Applications

Lung Wa Chung,† W. M. C. Sameera,‡ Romain Ramozzi,‡ Alister J. Page, Miho Hatanaka,‡ Galina P. Petrova, Travis V. Harris,‡,⊥ Xin Li, Zhuofeng Ke, Fengyi Liu, Hai-Bei Li, Lina Ding, and Keiji Morokuma*,‡ †Department of Chemistry, South University of Science and Technology of China, Shenzhen 518055, China ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan 2308, Australia Faculty of Chemistry and Pharmacy, University of Sofia, Bulgaria Boulevard James Bourchier 1, 1164 Sofia, Bulgaria Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, Shaanxi 710119, China School of Ocean, Shandong University, Weihai 264209, China School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, Henan 450001, China

Asymmetric phase-transfer catalysis with homo- and heterochiral quaternary ammonium salts: a theoretical study.

A thorough theoretical study of phase-transfer quaternary ammonium catalysts designed by the Maruoka group has been performed in an attempt to gain better understanding of the properties and catalytic behavior of the homo- and heterochiral forms of these systems. The conformationally flexible analogue is found to easily undergo interconversion from the homo- to the heterochiral form driven by the higher thermodynamic stability of the heterochiral isomer and resulting in alternation in catalytic behavior. Theoretical calculations of (1)H NMR spectra of the two isomers for different model systems are in good agreement with the experimental data, allowing us to conclude that the upfield shift of signals for the benzylic protons in the heterochiral form could be explained by an increase in the shielding effect of the aromatic parts of the system around these protons due to the conformational changes. By applying the automated transition state (TS) search procedure for the alkylation of glycine derivatives catalyzed by the homo-/heterochiral form of a conformationally rigid analogue, we were able to locate more than 40 configurations of the TS structures. In brief, the homochiral form was theoretically confirmed to catalyze the formation of the predominant R-product, while for the heterochiral form the catalytic activity is found to depend on two factors: (i) formation of a tight ion pair between the catalyst and the glycine derivative, which results in a decrease in the reaction rate, in agreement with the experimental data, and formation of only the R-product, and (ii) the possibility that the reaction occurs without the initial formation of the ion pair or after its dissociation, in which case the formation of an S-product is predominant. The combined effects of both factors would explain the lower reaction rate and the poor enantioselectivity observed experimentally for the heterochiral form.

Optical properties of solutions consisting of albumin and γ -globulin molecules in different ratio modeling blood serum

Rayleigh-Debye laser light scattering (RDLS) was used for study of the alterations of physical properties of albumin andγ-globulin molecules water solved in different ratios as a model system of blood serum. By using a portable optical device we simultaneously measured a number parameters of protein solutions such as the effective mass, coefficient of intermolecular interaction, diffusion coefficients of the components, etc. The results of the investigations for model systems were compared with the data obtained for blood serum of healthy and oncology patients.

The effect of lead cations on the fluorescence characteristics of bovine serum albumin in aqueous solution

The effect of lead (heavy metal) cations on the fluorescence characteristics and photophysical parameters (fluorescence intensity and anisotropy, absorption cross section, excited state lifetime, and rates of singlet-triplet conversion and reversible photobleaching) of tryptophan in an aqueous solution of bovine serum albumin (two-tryptophan protein) is studied and compared with the effect in the aqueous solution of tryptophan. It is demonstrated that the effect of lead on the fluorescence characteristics of the protein is manifested at a molar concentration ratio of metal cations and protein macromolecules of greater than 10 and related to the dynamic quenching of the excited state, protein aggregation, and an increase in the rate of singlet-triplet conversion (the effect of a heavy atom) in tryptophan molecules.

Optical Properties of Serum Albumin Water Solutions, Containing Mesoporous Silicon Particles

The interaction of molecules of bovine serum albumin (BSA) with silicon nanoparticles (SiNPs) was studied in water solutions of them at different pH values. The data of photon correlation spectroscopy and IR spectroscopy of studied solutions indicate the absence of interaction between BSA and SiNPs in the pH range 3–7, which is attested to by the experimentally obtained character of the pH dependence of the translational diffusion coefficient Dt and by the absence of hydrogen bonds between the protein carbonyl groups and the OH groups on the surface of mesoporous silicon nanoparticles. The obtained data may play a leading role in further in vivo application of silicon nanoparticles.

Using the dynamic light-scattering method for the analysis of a blood-serum model solution

We used photon correlation spectroscopy to investigate various dynamic processes that occur in samples of a blood-serum solution. These processes were induced by directional changes of the surface charges of macromolecules and the concentration of the solution. We suggest that the obtained associations between the translational diffusion coefficient value (Dt) and the medium pH value, as well as the protein concentration value, indicate the possibility of using the dynamic light scattering method for the effective diagnosis of common diseases, including cardiovascular lesions and cancers.

Multiparametric testing of blood protein solutions with diagnostic purpose

The multiparametric physical method for diagnosis and test of curing cancer diseases based on Rayleigh light scattering is proposed. There was studied simultaneously dynamic and static parameters of blood plasma and serum proteins. A special device for this purpose is described and clinical results are presented.

Method of light-scattering measurement in tumor diagnostics

The simple, inexpensive and effective multiparametric physical method for diagnosing oncological diseases based on Rayleigh light scattering is proposed. Dynamic and static parameters of plasma blood proteins in dilute water solutions with different pH and ionic strength were studied simultaneously for the first time.

Electrostatic interaction in biopolymer solutions investigated by NMR and laser light scattering

In solution the surface of protein macromolecules is always charged and so the electrostatic interaction between the polar solvent and charged groups on the biopolymer surface is strong enough. It is of interest to consider three types of interaction: protein - protein, protein - contrion, protein - solvent. All of these interactions can change as static parameters of macromolecules solution. This paper deals with the most suitable methods for measurement of these parameters. The methods are NMR (nuclear magnetic resonance) and laser light scattering.

Effect of heavy-metal ions on dynamic characteristics of collagen molecules in solutions

Effect of heavy (Pb2+, Cs+) and light (Na+) metal ions on the molecular-dynamic characteristics of type-I collagen in aqueous solution was studied using the method of dynamic light scattering. It was found that the dependence of the translational diffusion coefficient Dt from pH solutions has a nonlinear form with a pronounced extremum close to the isoelectric point of the protein (pI 6.0). For pure aqueous solution of protein there is a maximum of Dt in isoelectric point. For collagen solutions with the addition of heavy-metal salts the minimum of Dt was observed near the isoelectric point. This fenomenon is connected with the formation of protein nanoclusters in solution. With concentration of heavy metal ions increasing translational diffusion coefficient Dt decreases, which shows on increasing of aggregation effect. The addition of sodium ions in aqueous solution of collagen containing heavy metal ions sharp decreasing of the translational diffusion of molecules is observed. That can be connected with the rise of scattering particles masses.