非线性Schroedinger方程组的精确解组

运用Maple语言程序，在没有假设的条件下，得到了具有耦合特性的非线性Schrfidinger方程组的行波精确解组及其约束条件方程，它们的表达式涵盖了所有的耦合解组与非耦合解组，具有任意性。耦合解组的算例函数及其特性分析，解释了α螺旋蛋白质螺旋链运动模型的行波孤立子解的耦合效应，揭示了增加、稳定和控制蛋白质活性和功能的方向。文章的研究方法，为求解耦合的非线性微分方程组的行波精确解组探索了蹊径。     

Statistical Thermodynamic Properties of Linear Protein Solutions

利用统计力学理论结合格点模型,讨论了链状蛋白质分子溶液的热力学性质. 结果表明,对于稀溶液来说,溶液的吉布斯函数随蛋白质浓度的增加而降低,蛋白质分子化学势随其浓度增加而升高. 还分析了蛋白质分子链长及温度对溶液吉布斯函数和蛋白质分子化学势的影响. 并且计算讨论了几种第一类抗冻蛋白的化学势.     

α螺旋蛋白质螺旋链模型的精确解组

文章运用Maple语言程序,在没有假设的条件下,得到了α螺旋蛋白质螺旋链运动模型方程组的行波精确解组,它涵盖了所有的耦合解组与非耦合解组,具有任意性.耦合解组的算例函数及其特性分析,解释了α螺旋蛋白质螺旋链运动模型的行波孤立子解的耦合效应,揭示了增加、稳定和控制蛋白质活性和功能的方向,文章的研究方法,为求解生物大分子螺旋链运动模型的行波精确解组探索了溪径.     

α螺旋蛋白质螺旋线模型的耦合孤立子

在已得到的α螺旋蛋白质分子各向异性耦合薛定谔方程组的基础上, 给出了该方程组的孤立子解, 并对其解进行了分析和讨论. 关键词：     

Relaxivities of human liver and spleen ferritin

Ferritin, the iron-storing protein of mammals, is known to darken T₂-weighted magnetic resonance images. This darkening can be used to noninvasively measure an organ's iron content. Significant discrepancies exist between T₂ data obtained with ferritin-containing tissues and with aqueous solutions of horse spleen ferritin (HSF). The NMR properties of stable human ferritin have never been studied in aqueous solutions. Relaxometry results on human liver and spleen ferritin are reported here, showing that the relaxation induced in aqueous solutions by human ferritins is comparable to that induced by HSF. As a consequence, the differences between ferritin-containing human tissues and ferritin solutions cannot be attributed to different NMR properties of human and horse ferritins, but probably to a clustering of the protein in vivo.     

Microquantification of Proteins by Spectrophotometry. Part II : Application Procedure for Complex Mixture Containing Interfering Substances

In a previous paper we have shown that it was possible to quantify protein solutions at very weak concentrations directly by UV-visible spectroscopy. Nevertheless the protein quantification could not be possible if there is any trace of interferents left in the solution. So it is necessary to eliminate all the interferents to make the measure at 190 and/or 277 nm possible. We have developped a method based on the use of Microcon membranes and centrifugation. Interferents could be eliminated from protein solutions after four centrifugations at 13000 g during 5 min. This procedure allowed the recovering of proteins, with 80 to 99 % yield, and thus making microquantification possible.

This method is particularly interesting for enzymatic solutions after a purification procedure by HPLC where very tiny quantities of protein are recovered. This protocol has been tested on three enzymes; enzymatic activity recovered after four centrifugations was quite high for PEPcase and malic enzyme (71 and 64 % respectively).     

Effects of ultrasound on the thermal and structural characteristics of proteins in reconstituted whey protein concentrate

The sonication-induced changes in the structural and thermal properties of proteins in reconstituted whey protein concentrate (WPC) solutions were examined. Differential scanning calorimetry, UV-vis, fluorescence and circular dichroism spectroscopic techniques were used to determine the thermal properties of proteins, measure thiol groups and monitor changes to protein hydrophobicity and secondary structure, respectively. The enthalpy of denaturation decreased when WPC solutions were sonicated for up to 5 min. Prolonged sonication increased the enthalpy of denaturation due to protein aggregation. Sonication did not alter the thiol content but resulted in minor changes to the secondary structure and hydrophobicity of the protein. Overall, the sonication process had little effect on the structure of proteins in WPC solutions which is critical to preserving functional properties during the ultrasonic processing of whey protein based dairy products.     

Kinetics of supersaturation decay in the crystallization of lysozyme

The molecular architecture of proteins can be determined by analysing the X-ray diffraction patterns of their crystals. The technology of X-ray crystallography has reached the point, however, where the determination of the structure of a given crystal is controlled by the limited availability of the crystals themselves. Proteins can often be crystallized from pH buffered aqueous solutions of strong electrolytes. When dissolved protein in solution is more stable than crystalline protein, the appearance of crystals can be said to be under thermodynamic control. If, on the other hand, the crystals are more stable than the dissolved protein, and still crystals are slow to appear, the crystallization can be said to be under kinetic control. Using dilatometry, we have followed the rate of decay of the protein supersaturation in crystallizing solutions of chicken egg-white lysozyme under conditions of kinetic control. We have found that the rate of decay of the supersaturation is first order in the supersaturation and that the rate constant is independent of the initial protein concentration, but increases with increasing pH, decreasing temperature, and with increasing concentrations of sodium chloride and buffer salt. We correlate these observed trends in the rate constant with related trends in the solubility and surface charge density of the crystals. We conclude that the rate constant for supersaturation decay is inversely proportional to the protein solubility.     

Nuclear magnetic relaxation and dynamics of biopolymers

A model is proposed in which the NMR relaxation dispersion profiles of biomolecule water solutions are interpreted in terms of magnetic field fluctuations due to the backbone vibrations involving the biopolymer paramagnetic nuclei. This model, which takes into account the experimental evidence which has appeared in the literature for a “fractal-like” density of vibrational state for the protein backbone, has been used to fit some experimental NMR relaxation profiles of biomolecule water solutions. The results obtained are discussed critically in connection with the data reported in the related literature.     

Viscoelastic phase separation of protein solutions

In addition to the known behavior of normal phase separation and gelation, we report novel phase-separation behavior of protein solutions as their intermediate case. A network structure of the protein-rich phase may be formed even if it is the minority phase, contrary to the conventional wisdom. This behavior is characteristic of viscoelastic phase separation found in polymer solutions. This kinetic pathway may play crucial roles in the complex phase ordering of protein solutions, in particular, protein network formation in biological systems and foods.     

Molecular association processes and fluorescent characteristics of nanomarkers of the fluorescein family in solutions of bovine serum albumin

An analysis of the molecular association and fluorescent characteristics of nanomarkers of the fluorescein family, viz., fluorescein, erythrosine, eosine, and Rose Bengal, in BSA solutions was conducted. For all the markers a decreasing degree of molecular association was observed in the BSA solutions as compared with the solutions without protein. In the solutions with BSA, fluorescence quenching and red shifting of the fluorescence spectrum maximum occurred for the solutions with BAS compared with solutions without protein for the markers of the fluorescein family. The dependences of the degree of molecular association on pH differed for fluorescein and its halogen derivatives. The efficiency dependences of nanomarker binding with BSA on pH differed for fluorescein and its halogen derivatives.     

Coupling of two motor proteins: a new motor can move faster

We study the effect of a coupling between two motor domains in highly processive motor protein complexes. A simple stochastic discrete model, in which the two parts of the protein molecule interact through some energy potential, is presented. The exact analytical solutions for the dynamic properties of the combined motor species, such as the velocity and dispersion, are derived in terms of the properties of free individual motor domains and the interaction potential. It is shown that the coupling between the motor domains can create a more efficient motor protein that can move faster than individual particles. The results are applied to analyze the motion of RecBCD helicase molecules.     

Binding of Fluorescein Isothiocyanate to Insulin: A Fluorimetric Labeling Study

The determination of the fluorophore to the protein molar ratio has been studied using fluorescence spectroscopy. The tyrosine fluorescence is measured from insulin (Ins) solutions at wavelengths lambda(ex)/lambda(em) = 276/300 nm and from fluorescein isothiocyanate (FITC) solutions at lambda(em)/lambda(em) = 494/518 nm. Series of solutions prepared from insulin and FITC are tested for conjugation, recording their fluorimetric intensities. Fluorimetric titrations with different formal concentrations are followed either by intrinsic and extrinsic emission intensities at lambda(ex)/lambda(em) = 276 or 494/518 nm and by their typical emission spectra at pH 9.0. All results denoted a binding ratio of 3 moles of FITC/mole of Ins.     

The role of disaccharides for protein–protein interactions – a SANS study

ABSTRACT

The disaccharide trehalose has shown outstanding anti-aggregation properties for proteins, which are highly important for the possibility to treat neurodegenerative diseases, such as Alzheimer’s and Huntington’s disease. However, the role and mechanism of trehalose for such stabilising effects are still largely unknown, partly because a direct structural picture of how trehalose organises around proteins in an aqueous system is missing. Here we compare small-angle neutron scattering (SANS) data on myoglobin in aqueous solutions of either sucrose or trehalose, in order to investigate their effect on protein–protein interactions. We find that both trehalose and sucrose induces a well-defined protein–protein distance, which could explain why these inhibit protein–protein interactions and associated protein aggregation. It does not however explain the superior anti-aggregation effect of trehalose and suggests that the local solvent structures are highly important for explaining the protein stabilisation mechanism. In a broader perspective, these findings are important for understanding the role of sugars in biological stabilisation, and could provide a structural explanation for why trehalose is a promising candidate for the treatment of neurodegenerative and other protein aggregation related diseases.     

Phase transitions in crystals of protein amino acids with trapped drops of water solutions

It has been shown that the phase transitions observed at temperatures of about 250 K in crystals of protein amino acids and of their compounds grown from water solutions are related to drops of these solutions trapped by crystals in their growth.     

Combinatorial chemistry of β-hairpins

Combinatorial chemistry is expanding rapidly both in terms of chemistry development and application to the synthesis of compound libraries for lead discovery and optimization. Combinatorial technologies continue evolving and developing, in fact they are being used as basic research tools in different fields that include peptide/protein folding. This review examines the use of combinatorial chemistry in the design of peptides and protein domains that adopt beta-sheet conformations. In particular, the use of conformationally restricted peptide libraries has allowed the identification of linear peptides that are folded in a beta-hairpin structure in plain aqueous solutions.     

Breathers and solitons for the coupled nonlinear Schr?dinger system in three-spine α-helical protein

We mainly investigate the variable-coefficient 3-coupled nonlinear Schr?dinger(NLS) system, which describes soliton dynamics in the three-spine α-helical protein with inhomogeneous effect. The variable-coefficient NLS equation is transformed into the constant coefficient NLS equation by similarity transformation firstly. The Hirota method is used to solve the constant coefficient NLS equation, and then we get the one-and two-breather solutions of the variable-coefficient NLS equation. The results show that, in the background of plane waves and periodic waves, the breather can be transformed into some forms of combined soliton solutions. The influence of different parameters on the soliton solution and the collision between two solitons are discussed by some graphs in detail. Our results are helpful to study the soliton dynamics inα-helical protein.     

Complex formation of CdSe/ZnS/TOPO nanocrystal vs. molecular chaperone in aqueous solution by hydrophobic interaction

Feasibilities to stabilize CdSe/ZnS/trioctylphosphineoxide (TOPO) nanocrystals (quantum dots, QDs) in aqueous solutions with prefoldin macromolecules in their bioactive states are reported. Prefoldin is a jellyfish-shaped hexameric co-chaperone of the group II chaperonins. As a protein folding intermediate is captured within its central cavity, so CdSe/ZnS/TOPO QDs would also be included within this cavity. It is also found the QDs can be much more dispersed in aqueous solutions and suspended for certain period of time by adding trace amount of t-butanol in the buffer prior to the mixing of the QDs mother solution. While biochemical procedures are evaluated with ordinary fluorescence measurements, possible complex formations are also evaluated with TIRFM single-molecule detection techniques.     

Interaction of EHF radiation with biomolecular systems

Data on the absorption of EHF electromagnetic energy by aqueous solutions are summarized. Experimental tests for positive (hydrophilic and hydrophobic) and negative (hydrophilic) hydration are formulated. The applicability of the proposed approach to the study of the hydration of high-molecular-weight systems, including aqueous solutions of proteins, is demonstrated. A model is proposed that explains the interaction of EHF radiation with real biological systems, including under conditions of EHF therapy. The experimental data on the absorption of EHF radiation by aqueous solutions of organic and inorganic electrolytes and nonelectrolytes as well as globular proteins are used to construct a model that explains certain details of EHF therapy. The fraction of mobile water molecules in the skin is considered the primary molecular target for EHF radiation; they are capable of transporting the EHF energy to primary physiological targets of the protein type.Institute of Radio Engineering and Electronics, Russian Academy of Sciences. Institute of Organic Chemistry, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 42–55, January, 1994.     

Complex protein patterns formation via salt-induced self-assembly and droplet evaporation

Complex and elegant protein patterns in rosette, scallop, Chinese arrow and dendrite shapes at macroscopic length scales were prepared using salt-induced molecular self-assembly and droplet evaporation methods. The direct visual observation method using fluorescence microscopy was adopted to characterize the formation of these protein patterns in situ. Further studies from an optical interferometric profiler have shown that both rosette and scalloped protein patterns are hierarchical structures of concentric rings consisting of many prism-like columnar stacks, with each of the stack having thousands of protein molecules. Systematic experimental studies were performed to investigate the influence of salt concentration, protein concentration and evaporation rate on the morphologies of protein patterns. Upon the analysis of the representative fluorescent microscope images some theoretical explanations, based on Deegan’s theory on the “coffee ring” effect and the dynamic self-assembly mechanism, were proposed to illustrate the dynamics for the formation of different protein patterns. Two different evaporation modes have been found: edge-enhanced evaporation for low salt concentration solutions, i.e., the higher evaporation rate exists at the edge of the droplet; center-enhanced evaporation for high salt concentration solutions, in which faster evaporation occurs at the droplet center consisting of a lot of crystallized salts.