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71.
Sabyasachi Ta Milan Ghosh Noor Salam Jayanta Das Manirul Islam Paula Brandão Vítor Félix Jesus Sanmartin Debasis Das 《应用有机金属化学》2020,34(10):e5823
An amide-imine conjugate, (E)-N′-((2-hydroxybenzen-1-yl) methylene)-4-methylbenzohydrazide (H2LPTASAL), derived from 4-methyl-benzoic acid hydrazide (PTA) and 2-hydroxybenzaldehyde is used to prepare Mo (VI), Cu (II) and Fe (III) complexes. The X-ray structurally characterized complexes have been explored as catalyst for amine assisted asymmetric ring opening (ARO) of epoxide, carbon-heteroatom cross-coupling and ethyl benzene oxidation. In addition, their catecholase like activities have thoroughly been investigated. Moreover, the Cu (II) complex selectively recognizes histidine by fluorescence spectroscopy. 相似文献
72.
73.
Steady-State and Time Resolved Fluorescence Analysis on Tyrosine–Histidine Model Compounds 总被引:1,自引:1,他引:0
Four model compounds, for a tyrosine–histidine covalent bonding, 2-(5-imidazolyl)-4-methylphenol (C–C bonding in ortho-position at the phenyl group); 2′-(1-imidazolyl)-4-methylphenol (C–N bonding in ortho′-position at the phenyl group); 2-(5-imidazolyl)-4-H-phenol and 2-(5-imidazolyl)-4-H-phenol, at physiological pH have been
studied by UV-Vis absorption, steady-state and time resolved fluorescence spectroscopy. Their absorption and emission properties
are presented and discussed. The photophysical properties depend on the para-substituted phenyl group as well as on C–C/C–N bonding in the Phenol–Imidazole linkage. The N position, N1–N3/N1–N4, in the imidazole group was found to be relevant. The results are discussed with relevance to the redox processes of tyrosine
and to better understand the role of a tyrosine–histidine covalent linkage as found in cytochrome c oxidase. 相似文献
74.
de Farias R. F. Nunes L. M. Airoldi C. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):923-930
Infrared spectroscopy, thermogravimetry and differential scanning calorimetry techniques were used to study the metal-amino
acid interactions for adducts of the general formula CdCl2·nL (n=1.0 or 1.5 and L=histidine or cysteine). After characterization the thermal degradation process was kinetically followed by a non-isothermal
method. The infrared data confirmed that the cation is coordinated the carboxylic oxygen atoms of the amino acid molecules.
The thermogravimetric results indicated that the main step of the thermal degradation of all amino acid adducts is connected
to the rupture of the metal-ligand bonds, to give the associated activation energies values of 77, 44, 55 and 41 kJ mol-1 for CdCl2·nL, n=1.0 and 1.5, for histidine and cysteine, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
75.
《Electroanalysis》2017,29(2):392-397
Copper(II) complexes with cysteine and histidine, amino acids that coordinate copper(II) in human body, were investigated. Cu‐His and Cu‐Cys complexes were detected in pH range from 5.0 to 9.0 using voltammetric techniques. [CuHis2] complex reduces by two‐electron reversible process at ≈−0.40 V, while [CuCys] complex by one‐electron quasireversible process at −0.6 V, revealing strong adsorption at the electrode surface. When both amino acids are present in the solution, new peak appeared at −0.5 V, which corresponded to the [CuHisCys] complex reduction. Formation and characterization of mixed ligand complex was also supported by UV‐Vis spectra recorded at fixed histidine and various cysteine concentrations. Formation of [CuHisCys] complex in the solution was detected and stability constant calculated to amount to log K CuHisCys=16.9±0.3. This study was the first attempt to characterize formation of Cu(II) mixed ligand complexation process with biochemically important amino acids in electron transport and oxygenation reactions in human body. 相似文献
76.
稀土组氨酸配合物的合成和性质研究 总被引:1,自引:0,他引:1
本文合成了十二个稀土与L-组氨酸(L-His)的固体配合物,元素分析结果表明配合物的组成为Ln(His)3(NO3)32H2O(Ln=Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Er,Tm)。并通过配合物的IR、UV、H-NMR、TG-DTA、磁化率及在水中的摩尔电导等的研究,表征了这些配合物的物理化学性质,结果表明稀土组氨配合物中配体通过羟基氧原子与镧系离子配位。 相似文献
77.
Hwai-Chien Chan Bianca Bueno Dr. Adrien Le Roch Prof. Dr. Alexandre Gagnon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(53):13330-13336
The N-arylation of the side chain of histidine by using triarylbismuthines is reported. The reaction is promoted by copper(II) acetate in dichloromethane at 40 °C under oxygen in the presence of diisopropylethylamine and 1,10-phenanthroline and allows the transfer of aryl groups with substituents at any position of the aromatic ring. The reaction shows excellent functional group tolerance and is applicable to dipeptides where the histidine is located at the N terminus. A histidine-guided backbone N−H arylation was observed in dipeptides where the histidine occupies the C terminus. 相似文献
78.
Panayiotis Bilalis Spyridon Varlas Aikaterini Kiafa Athanassios Velentzas Dimitrios Stravopodis Hermis Iatrou 《Journal of polymer science. Part A, Polymer chemistry》2016,54(9):1278-1288
A series of novel multi‐responsive disulfide cross‐linked polypeptide nanogels has been synthesized by a one‐step ring‐opening polymerization process. The pH‐responsive core of the prepared nanogels was based on poly(L‐histidine), the difunctional N‐carboxy anhydride of l ‐cystine (l ‐Cys‐NCA) was used as a reduction‐cleavable cross‐linking agent, while the outer hydrophilic corona was comprised of a poly(ethylene oxide) block. Extensive molecular characterization studies were conducted in order to confirm the formation of the desired polymeric nanostructures and also to prove their responsiveness to external stimuli within the physiological values of healthy and cancer tissues. Furthermore, the disruption of the disulfide‐bond linkages between the polymeric chains was achieved by the presence of the reductive tripeptide glutathione (GSH), leading to size variations that were monitored by dynamic light scattering (DLS) and size‐exclusion chromatography (SEC). “Stealth” properties of the formed nanostructures were examined by zeta potential measurements. The described nanogels are clearly promising candidates for drug delivery applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1278–1288 相似文献
79.
There is an urgent need to find new antibacterial agents to combat bacterial infections, including agents that inhibit novel, hitherto unexploited targets in bacterial cells. Amongst novel targets are two-component signal transduction systems (TCSs) which are the main mechanism by which bacteria sense and respond to environmental changes. TCSs typically comprise a membrane-embedded sensory protein (the sensor histidine kinase, SHK) and a partner response regulator protein. Amongst promising targets within SHKs are those involved in environmental signal detection (useful for targeting specific SHKs) and the common themes of signal transmission across the membrane and propagation to catalytic domains (for targeting multiple SHKs). However, the nature of environmental signals for the vast majority of SHKs is still lacking, and there is a paucity of structural information based on full-length membrane-bound SHKs with and without ligand. Reasons for this lack of knowledge lie in the technical challenges associated with investigations of these relatively hydrophobic membrane proteins and the inherent flexibility of these multidomain proteins that reduces the chances of successful crystallisation for structural determination by X-ray crystallography. However, in recent years there has been an explosion of information published on (a) methodology for producing active forms of full-length detergent-, liposome- and nanodisc-solubilised membrane SHKs and their use in structural studies and identification of signalling ligands and inhibitors; and (b) mechanisms of signal sensing and transduction across the membrane obtained using sensory and transmembrane domains in isolation, which reveal some commonalities as well as unique features. Here we review the most recent advances in these areas and highlight those of potential use in future strategies for antibiotic discovery. This Review is part of a Special Issue entitled “Interactions of Bacterial Molecules with Their Ligands and Other Chemical Agents” edited by Mary K. Phillips-Jones. 相似文献
80.
Hirotsugu Hiramatsu Noriko Miki Hideo Takeuchi 《Journal of Raman spectroscopy : JRS》2010,41(12):1708-1713
Histidine is an important and versatile amino acid residue that plays a variety of structural and functional roles in proteins. Although the Raman bands of histidine are generally weak, histidine in the N‐deuterated cationic form with imidazole Nπ D and Nτ D bonds (N‐deuterated histidinium) gives two strong Raman bands assignable to the C4C5 stretch (νCC) and the Nπ C2 Nτ symmetric stretch (νNCN) of the imidazole ring. We examined the Raman spectra of N‐deuterated histidinium in 12 crystals with known structures. The observed νCC and νNCN wavenumbers were analyzed to find empirical correlations with the conformation and hydrogen bonding. The effect of conformation on the vibrational wavenumber was expressed as a threefold cosine function of the Cα Cβ C4C5 torsional angle. The effect of hydrogen bonding at Nπ or Nτ was assumed to be proportional to the inverse sixth power of the distance between the hydrogen and acceptor atoms. Multiple linear regression analysis clearly shows that the conformational effect on the vibrational wavenumber is comparable for νCC and νNCN. The hydrogen bond at Nπ weakly lowers the νCC wavenumber and substantially raises the νNCN wavenumber. On the other hand, the hydrogen bond at Nτ strongly raises the νCC wavenumber but does not affect the νNCN wavenumber. These empirical correlations may be useful in Raman spectral analysis of the conformation and hydrogen bonding states of histidine residues in proteins. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献