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Kuo NN Huang JJ Miksovska J Chen RP Larsen RW Chan SI 《Journal of the American Chemical Society》2005,127(48):16945-16954
As part of our continuing study of the effects of the turn sequence on the conformational stability as well as the mechanism of folding of a beta-sheet structure, we have undertaken a parallel investigation of the solution structure, conformational stability, and kinetics of refolding of the beta-sheet VFIVDGOTYTEV(D)PGOKILQ. The latter peptide is an analogue of the original Gellman beta-sheet VFITS(D)PGKTYTEV(D)PGOKILQ, wherein the TS(D)PGK turn sequence in the first hairpin has been replaced by VDGO. Thermodynamics studies revealed comparable conformational stability of the two peptides. However, unlike the Gellman peptide, which showed extremely rapid refolding of the first hairpin, early kinetic events associated with the refolding of the corresponding hairpin in the VDGO mutant were found to be significantly slower. A detailed study of the conformation of the modified peptide suggested that hydrophobic interactions might be contributing to its stability. Accordingly, we surmise that the early kinetic events are sensitive to whether the formation of the hairpin is nucleated at the turn or by sequestering of the hydrophobic residues across the strand, before structural rearrangements to produce the nativelike topology. Nucleation of the hairpin at the turn is expected to be intrinsically rapid for a strong turn. However, if the process must involve collapse of hydrophobic side chains, the nucleation should be slower as solvent molecules must be displaced to sequester the hydrophobic residues. These findings reflect the contribution of different forces toward nucleation of hairpins in the mechanism of folding of beta-sheets. 相似文献
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Jaromíra Chýlková Renáta Šelešovská-Fadrná Jaroslava Machalíková 《Central European Journal of Chemistry》2007,5(2):479-495
The optimal process of pre-treatment and activation of gold rotating disc electrode (AuRDE) before voltammetric determination
of mercury is proposed. This treatment encompasses polishing of the electrode surface, electrochemical cycling, and activation.
This procedure both increases determination sensitivity as well as improves determination reproducibility. The detection limit
on the working electrode achieved using this approach amounted to 8.26·10−10 mol L−1for direct mercury determination in water solution (applying 200 s running accumulation). The procedure of the quantitative
mercury isolation from complicated sample matrix was developed as well. It provides better selectivity and significant increase
of sensitivity of mercury determination. In case of mercury isolation from one liter of water the detection limit is 6.23·10−11 mol L−1 (analyzing a greater sample volume the determined concentration could be lower).
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Klára Melánová Ludvík Beneš Vítězslav Zima Jaroslava Kalousová Jiří Votinský 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(4):391-402
Mixed intercalates VOPO4.C2H5 OH.C4 H9OH, VOPO4.C3H7 OH.C5H11OH, VOPO4.C3H7 OH.C6H13OH and VOPO4.C4H9 OH.C6H13OH have been prepared by reaction of polycrystalline vanadyl phosphate dihydrate with liquid mixtures of the 1-alkanols in a microwave field. The same mixed layer-type complexes were also obtained as intermediary products of exchange reactions consisting in substitution of one alkanol bound in the solid intercalate by another alkanol introduced in the form of vapour. The composition of products has been determined, and the basal spacing of all the mixed layer-type complexes prepared has been found by diffraction. A structural principle is suggested which governs the depositing of two kinds of 1-alkanol molecules (differing in the lengths of their aliphatic chains) while acting as guests in the layered structure of vanadyl phosphate. 相似文献
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Holló Berta Barta Ristić Ivan Budinski-Simendić Jaroslava Cakić Suzana Szilágyi Imre Miklós Szécsényi Katalin Mészáros 《Journal of Thermal Analysis and Calorimetry》2018,132(1):215-224
Journal of Thermal Analysis and Calorimetry - To overcome the polyurethanes low heat resistance and obtain new PU-based materials, in continuation of our research in the synthesis of hybrid... 相似文献
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Portfolio Selection and Transactions Costs 总被引:1,自引:0,他引:1
This paper deals with the portfolio selection problem of risky assets with a diagonal covariance matrix, upper bounds on all assets and transactions costs. An algorithm for its solution is formulated which terminates in a number of iterations that is at most three times the number of assets. The efficient portfolios, under appropriate assumptions, are shown to have the following structure. As the risk tolerance parameter increases, an asset's holdings increases to its target, then stays there for a while, then increases to its upper bound, reaches it and stays there. Then the holdings of the asset with the next highest expected return proceeds in a similar way and so on. 相似文献
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Effectiveness of the Photoactive Dye Methylene Blue versus Caspofungin on the Candida parapsilosis Biofilm in vitro and ex vivo 下载免费PDF全文
Lucia Černáková Jaroslava Chupáčová Katarína Židlíková Helena Bujdáková 《Photochemistry and photobiology》2015,91(5):1181-1190
This research studied the effectiveness of the photoactive compound methylene blue (MB) activated with red LED light (576–672 nm) compared to that of caspofungin (CAS) on 1 Candida albicans and 3 Candida parapsilosis strains. Results were evaluated in terms of SMIC50 for CAS or in PDI (photodynamic inactivation)‐SMIC50 for MB (minimal inhibitory concentration inhibiting sessile biofilm to 50% in comparison to the control without CAS or after irradiation in comparison to the control without MB). While all strains were susceptible to CAS in planktonic form, the SMIC50 was determined to be >16 μg mL?1 when CAS was added to a 24 h biofilm. However, PDI‐MIC50s (1.67 mW cm?2, fluence 15 J cm?2) were 0.0075–0.03 mmol L?1. For biofilm, PDI‐SMIC50s were in the range from 0.7 to 1.35 mmol L?1. MB concentration of 1 mmol L?1 prevented a biofilm being formed ex vivo on mouse tongues after irradiation regardless of the application time, in contrast to CAS, which was only effective at a concentration of 16 μg mL?1 when it was added at the beginning of biofilm formation. PDI seems to be a promising method for the prevention of microbial biofilms that do not respond significantly to conventional drugs. 相似文献