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131.
Statins are commonly used to control hypercholesterolemia and to prevent cardiovascular diseases. Among the statins, Simvastatin is one of the most frequently prescribed statins because of its efficacy in reducing LDL lipoprotein cholesterol levels, its tolerability, and its reduction of cardiovascular risk and mortality. Conflicting results have been reported with regard to benefits (pleiotropic effects) as well as risks (adverse effects) of simvastatin on different soft and hard tissues. In the current study, Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to obtain detailed information about protein conformational changes due to simvastatin therapy of soft tissues namely liver, testis, sciatic nerve and hard tissues such as femur and tibia. Protein secondary structural changes were predicted by intensity calculations from second derivative spectra and neural network (NN) analysis, using the amide I band (1700-1600 cm(-1)) of FTIR spectra. Moreover, based on protein secondary structural differences, hierarchical cluster analysis was carried out in the 1700-1600 cm(-1) region. The results of our study in liver, testis and sciatic nerve tissues revealed that simvastatin treatment significantly decreased alpha helix structure and beta sheet structure at 1638 cm(-1), while increased the anti-parallel and aggregated beta sheet and random coil structures implying a simvastatin-induced protein denaturation in treated groups. Different to soft tissues, the results of hard tissue studies on femur and tibia bones revealed increased alpha helix structure and decreased anti-parallel beta sheet, aggregated beta sheet and random coil structures implying more strengthened bone tissues in simvastatin-treated groups. Finally, the simvastatin-treated and control groups for all soft and bone tissues were successfully differentiated using cluster analysis. According to the heterogeneity values in the cluster analysis of these tissues, the sciatic nerve tissue was found to be the most affected tissue from simvastatin treatment among the studied soft tissues. In addition, the high heterogeneity value implied high secondary structural difference between control and simvastatin-treated groups in tibia bone tissues. These findings reveal that FTIR spectroscopy with bioinformatic analyses such as neural network and hierarchical clustering, allowed us to determine the simvastatin-induced protein conformational changes as adverse and pleiotropic effects of the drug on different soft and hard tissues. 相似文献
132.
Boradiazaindacene dyads designed as energy transfer casettes can be modified to signal cation concentrations ratiometrically. If the energy transfer efficiency is increased via changing spectral overlap on cation binding, an enhancement of emission signal ratios can be obtained. A larger range of ratios results in highly improved sensitivity to analyte concentrations. We demonstrate this approach in a de novo design of a novel and highly selective ratiometric chemosensor for Hg(II) ions. 相似文献
133.
In this work, for the first time, we report pKa values of the amino functions in a target-bound aminoglycoside antibiotic, which permitted dissection of the thermodynamic properties of an enzyme-aminoglycoside complex. Uniformly enriched 15N-neomycin was isolated from cultures of Streptomyces fradiae and used to study its binding to the aminoglycoside phosphotransferase(3')-IIIa (APH) by 15N NMR spectroscopy. 15N NMR studies showed that binding of neomycin to APH causes upshifts of approximately 1 pKa unit for the amines N2' and N2' ' while N6' experienced a 0.3 pKa unit shift. The pKa of N6' ' remained unaltered, and resonances of N1 and N3 showed significant broadening upon binding to the enzyme. The binding-linked protonation and pH dependence of the association constant (Kb) for the enzyme-aminoglycoside complex was determined by isothermal titration calorimetry. The enthalpy of binding became more favorable (negative) with increasing pH. At high pH, binding-linked protonation was attributable mostly to the amino functions of neomycin; however, at neutral pH, functional groups of the enzyme, possibly remote from the active site, also underwent protonation/deprotonation upon formation of the binary enzyme-neomycin complex. The Kb for the enzyme-neomycin complex showed a complicated dependence on pH, indicating that multiple interactions may affect the affinity of the ligand to the enzyme and altered conditions, such as pH, may favor one or another. This work highlights the importance of determining thermodynamic parameters of aminoglycoside-target interactions under different conditions before making attributions to specific sites and their effects on these global parameters. 相似文献
134.
Four ruthenium‐N‐heterocyclic carbene complexes ( 3–6 ) have been prepared and the new compounds characterized by C, H, N analyses, 1H‐NMR and 13C‐NMR. The reduction of ketones to alcohols via transfer hydrogenation was achieved with catalytic amounts of complexes 3–6 in the presence of t‐BuOK. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
135.
Novel palladium‐1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene (2a–c) and palladium‐1,3‐dialkylimidazolin‐2‐ylidene complexes (4a,b) have been prepared and characterized by C, H, N analysis, 1H‐NMR and 13C‐NMR. Styrene or phenylboronic acid reacts with aryl halide derivatives in the presence of catalytic amounts of the new palladium‐carbene complexes, PdCl2(1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene) or PdCl2(1,3‐dialkylimidazolin‐2‐ylidene) to give the corresponding C? C coupling products in good yields. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
136.
We determine bounds for the spectral and ??p norm of Cauchy–Hankel matrices of the form Hn=[1/(g+h(i+j))]ni,j=1≡ ([1/(g+kh)]ni,j=1), k=0, 1,…, n –1, where k is defined by i+j=k (mod n). Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
137.
Near‐IR‐Triggered,Remote‐Controlled Release of Metal Ions: A Novel Strategy for Caged Ions
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Ahmet Atilgan Dr. Esra Tanriverdi Eçik Dr. Ruslan Guliyev T. Bilal Uyar Dr. Sundus Erbas‐Cakmak Prof. Dr. Engin U. Akkaya 《Angewandte Chemie (International ed. in English)》2014,53(40):10678-10681
A ligand incorporating a dithioethenyl moiety is cleaved into fragments which have a lower metal‐ion affinity upon irradiation with low‐energy red/near‐IR light. The cleavage is a result of singlet oxygen generation which occurs on excitation of the photosensitizer modules. The method has many tunable factors that could make it a satisfactory caging strategy for metal ions. 相似文献
138.
Abstract: From the reaction of electron-rich olefins, bis(1,3-dimethylbenzimidazolidine-2-ylidene), I, or bis(3-methylbenzothiazolidine-2-ylidene), II with proton active compounds, such as dimethyl phosphite, diethyl phosphite, acetonitrile and benzaldehyde were obtained 2-substituted benzimidazole or benzothiazole derivatives. The compounds synthesized were identified by 1H, 13 C, 31P-NMR, mass, FT-IR spectroscopic techniques and micro analysis. 相似文献
139.
Cemil İbiş Nihal Yilmaz Bozkurt 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):695-701
Nitrodiene compound 1 was stirred with allylthiol for a long time and compound 3 was obtained. Compound 1 gave bis(thio)substituted 2-nitrodiene compound 4 and tris(thio)substituted 2-nitrodiene compound 5 with 2 moles allylthiol in the presence of NaOH in ethanol. Mono(allylthio)substituted diene compound 3 gave dibutadienyl substituted piperazine compounds with piperazine 6 in CH 2 Cl 2 (or diethylether). Compound 3 gave compound 9 with compound 8 . Compounds 11a-e have been obtained from the reaction of compound 3 with compounds 10a-e . Nach langem Rühren von der Verbindung 1 mit Allylthiol entsteht die Verbindung 3 . Die Verbindung 1 liefert mit zwei Mol von Allylthiol in ethanolischer Natronlunge die bis(thio)substituierte 2-Nitrodienverbindung 4 und tris(thio)substituierte Dienverbindung 5 . Mono(allylthio)substituierte Dienverbindung 3 ergibt mit Piperazine in CH 2 Cl 2 (oder in Ether) die dibutadienylsubstituierte Piperazinverbindung 7 . Die Verbindung 3 liefert mit der Verbindung 8 die Verbindung 9 . Durch die Reaktion von der Verbindungen 10a-c wurden die Verbindungen 11a-e erhalten. 相似文献
140.
Yasemin Soydas Bozkurt Halil Kutuk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2250-2257
Abstract In this study, some N-(p-substituted-arylsulfinyl)phthalimides (1a–1e) were synthesized. The synthesized compounds were examined with respect to their substitution reactions with sodium ethoxide, sodium methoxide, methylamine, and t-butylamine in dioxane. The substituent effect was investigated at 30.0 ± 0.1 °C. The activation entropy was also studied, and negative ΔS≠ values were obtained. Configuration inversions were observed in the substitution reactions. This result is in conformity with the SN2 mechanism. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Characterization of -(p-Substituted-arylsulfinyl)phthalimides 1a–b.] 相似文献