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71.
72.
Courty S Dollet B Kassner K Renault A Graner F 《The European physical journal. E, Soft matter》2003,11(1):53-59
We investigate the mechanical properties of a two-dimensional amorphous solid. It is formed spontaneously by the adsorption
of a protein (the β-lactoglobulin) at the surface of water. We measure its mechanical response in both elastic and plastic
regimes by applying a point-like force (using a glass fiber). We compare our results with previous measurements of shear moduli
using a floating torsion device.
Received: 10 February 2003 / Accepted: 23 April 2003 / Published online: 27 May 2003
RID="a"
ID="a"Present address: Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, UK; e-mail: sc374@phy.cam.ac.uk
RID="b"
ID="b"e-mail: graner@ujf-grenoble.fr 相似文献
73.
R. Antoine I. Compagnon D. Rayane M. Broyer Ph. Dugourd G. Breaux F.C. Hagemeister D. Pippen R.R. Hudgins M.F. Jarrold 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):583-587
The electric dipole moments of the isolated amino acid tryptophan and small glycine-based peptides (WGn, n = 1-5, W = tryptophan, G = glycine) have been measured by deflection of a molecular beam in an inhomogeneous electric field.
The measurements are compared to the results of ab initio calculations and Monte-Carlo simulations. The conformation and the flexibility of the peptides, at different temperatures,
are discussed. The WGn peptides are much more floppy than an isolated tryptophan, even a single glycine is enough to make the peptide floppy on
the timescale of the electric deflection measurements.
Received 4 January 2002 Published online 13 September 2002 相似文献
74.
In the present report, the use of negatively charged surfactants as modifiers of the background electrolyte is reported using poly(dimethylsiloxane) (PDMS) microchips. In particular, the use of anionic surfactants, such as sodium dodecyl sulfate, phosphatidic acid, and deoxycholate, was studied. When surfactants were present in the run buffer, an increase in the electroosmotic flow (EOF) was observed. Two additional effects were also observed: (i) stabilization of the run-to-run EOF, (ii) an improvement in the electrochemical response for several biomolecules. In order to characterize the analysis conditions, the effects of different surfactant, electrolyte, and pH were studied. EOF measurements were performed using either the current monitoring method or by detection of a neutral molecule. The first adsorption/desorption kinetics studies are also reported for different surfactants onto PDMS. The separation of biologically important analytes (glucose, penicillin, phenol, and homovanillic acid) was improved decreasing the analysis time from 200 to 125 s. However, no significant changes in the number of theoretical plates were observed. 相似文献
75.
Jastrzebska M Barwinski B Mróz I Turek A Zalewska-Rejdak J Cwalina B 《The European physical journal. E, Soft matter》2005,16(4):381-388
Native and chemically stabilized porcine pericardium tissue was imaged by the contact mode atomic force microscopy (AFM), in air. Chemically stabilized pericardium is used as a tissue-derived biomaterial in various fields of the reconstructive and replacement surgery. Collagen type I is the main component of the fibrous layer of the pericardium tissue. In this study, the surface topography of collagen fibrils in their native state in tissue and after chemical stabilization with different cross-linking reagents: glutaraldehyde (GA), dimethyl suberimidate (DMS) and tannic acid (TA) was investigated. It has been found that chemical stabilization causes considerable changes in the surface topography of collagen fibrils as well as in the spatial organization of the fibrils within the tissue. The observed changes in the D-spacing pattern of the collagen fibril correspond to the formation of intrafibrilar cross-links, whereas formation of interfibrilar cross-links is mainly responsible for the observed tangled spatial arrangement of fibrils and crimp structure of the tissue surface. The crimp structure was distinctly seen for the GA cross-linked tissue. Surface heterogeneity of the cross-linking process was observed for the DMS-stabilized tissue. SDS-PAGE electrophoresis was performed in order to evaluate the stabilization effect of the tissues treated with the cross-linking reagents. It has been found that stabilization with DMS, GA or TA enhances significantly the tissue resistance to SDS/NaCl extraction. The relation between the tissue stability and changes in the topography of the tissue surface was interpreted in terms of different nature of cross-links formed by DMS, GA and TA with collagen. 相似文献
76.
Victor M. Anisimov Nikolay Anikin Vladislav Bugaenko Vladimir Bobrikov Alexey Andreyev 《Theoretical chemistry accounts》2003,109(4):213-219
Accurate electrostatic maps of proteins are of great importance in research of protein interaction with ligands, solvent
media, drugs, and other biomolecules. The large size of real-life proteins imposes severe limitations on computational methods
one can use for obtaining the electrostatic map. Well-known accurate second-order M?ller–Plesset and density functional theory
methods are not routinely applicable to systems larger than several hundred atoms. Conventional semiempirical tools, as less
resource demanding ones, could be an attractive solution but they do not yield sufficiently accurate calculation results with
reference to protein systems, as our analysis demonstrates. The present work performs a thorough analysis of the accuracy
issues of the modified neglect of differential overlap type semiempirical Hamiltonians AM1 and PM3 on example of the calculation
of the molecular electrostatic potential and the dipole moment of natural amino acids. Real capabilities and limitations of
these methods with application to protein modeling are discussed.
Received: 26 April 2002 / Accepted: 19 September 2002 /
Published online: 14 February 2003 相似文献
77.
After a soft ionizing method was established, MS (mass spectrometry) has become a more common tool in biochemistry because soft ionization made it possible to detect large molecules such as proteins. Many kinds of applications were established to further utilize MS for the identification or quantitation of biomolecules. In this review, we introduce recent applications with special focus on chemical modification techniques and chemical probes developed for the MS determination of biomolecules. 相似文献
78.
建立了水产品中氨苯砜及其代谢产物N-乙酰氨苯砜残留量同时测定的高效液相色谱-紫外检测法(HPLC-UV)。样品经1%氨化乙腈提取,正己烷去脂,MCX阳离子固相萃取柱富集净化,氮吹浓缩,定容过膜后测定。以甲醇和水为流动相,ZORBAX SB-C_(18)色谱柱梯度洗脱分离,采用保留时间定性,外标法定量。在最佳检测条件下,目标化合物质量浓度在5~200 ng/mL范围内线性关系良好(R^(2)> 0.999),检出限(LOD)为10.0μg/kg,定量限(LOQ)为20.0μg/kg。以不同类型的水产品为空白基质,在20,50,100μg/kg加标水平下,氨苯砜的回收率为70.1%~81.7%,N-乙酰氨苯砜的回收率为84.2%~109.5%,相对标准偏差(RSD)均小于10%。该方法能够实现大批量水产品中氨苯砜及其代谢物残留量的检测。 相似文献
79.
Aqueous Diels-Alder chemistry combined with a poly(ethylene glycol) (PEG) spacer was used to immobilize a diverse group of biomolecules onto a solid surface. Briefly, α, ω linear PEG conjugates were synthesized containing cyclopentadiene in the α position and either biotin, lactose, or protein A in the ω position. Linkers were coupled to N-maleimide (EMC)-functionalized glass substrates, and surface immobilization of biomolecules was confirmed by confocal fluorescence imaging. 相似文献
80.
S. Taneri M. Cemal Yalabık 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(3):403-407
We implement a model to represent the effect of the deformation of the backbone of a system of motor proteins while sliding
on a track filament. This model incorporates a nearest neighbor interaction term among the motors for the deformation energy.
Correlations induced by this term result in increased motor force for inter-particle distances small compared to the ratchet
period.
Received 20 February 2001 and Received in final form 31 May 2001 相似文献