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排序方式: 共有196条查询结果,搜索用时 171 毫秒
191.
Alla Synytsya Miluše Judexová Tomáš Hrubý Michal Tatarkovič Michaela Miškovičová Luboš Petruželka Vladimír Setnička 《Analytical and bioanalytical chemistry》2013,405(16):5441-5453
Chiroptical methods are widely used in structural and conformational analyses of biopolymers. The application of these methods to investigations of biofluids would provide new avenues for the molecular diagnosis of protein-misfolding diseases. In this work, samples of human blood plasma and hen egg white were analyzed using a combination of conventional and chiroptical methods: ultraviolet absorption/electronic circular dichroism (UV/ECD), Fourier transform infrared absorption/vibrational circular dichroism (FTIR/VCD), and Raman scattering/Raman optical activity (Raman/ROA). For comparison, the main components of these substances—human serum albumin (HSA) and ovalbumin (Ova)—were also analyzed by these methods. The ultraviolet region of the ECD spectrum was analyzed using the CDNN CD software package to evaluate the secondary structures of the proteins. The UV/ECD, FTIR/VCD, and Raman/ROA spectra of the substances were quite similar to those of the corresponding major proteins, while some differences were also detected and explained. The conclusions drawn from the FTIR/VCD and Raman/ROA data were in good agreement with the secondary structures calculated from ECD. The results obtained in this work demonstrate that the chiroptical methods used here can be applied to analyze not only pure protein solutions but also more complex systems, such as biological fluids. Figure
Analysis of human blood plasma and hen egg white by ECD, VCD and ROA. 相似文献
192.
Yan Zhang Jiande Wang Petru Apostol Darsi Rambabu Alae Eddine Lakraychi Xiaolong Guo Xiaozhe Zhang Xiaodong Lin Shubhadeep Pal Vasudeva Rao Bakuru Xiaohua Chen Alexandru Vlad 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310033
A new phosphonate-based anionic bimetallic organic framework, with the general formula of A4−Zn−DOBDP (wherein A is Li+ or Na+, and DOBDP6− is the 2,5-dioxido-1,4-benzenediphosphate ligand) is prepared and characterized for energy storage applications. With four alkali cations per formula unit, the A4−Zn−DOBDP MOF is found to be the first example of non-solvated cation conducting MOF with measured conductivities of 5.4×10−8 S cm−1 and 3.4×10−8 S cm−1 for Li4- and Na4- phases, indicating phase and composition effects of Li+ and Na+ shuttling through the channels. Three orders of magnitude increase in ionic conductivity is further attained upon solvation with propylene carbonate, placing this system among the best MOF ionic conductors at room temperature. As positive electrode material, Li4−Zn−DOBDP delivers a specific capacity of 140 mAh g−1 at a high average discharge potential of 3.2 V (vs. Li+/Li) with 90 % of capacity retention over 100 cycles. The significance of this research extends from the development of a new family of electroactive phosphonate-based MOFs with inherent ionic conductivity and reversible cation storage, to providing elementary insights into the development of highly sought yet still evasive MOFs with mixed-ion and electron conduction for energy storage applications. 相似文献
193.
Jitaru P Cozzi G Gambaro A Cescon P Barbante C 《Analytical and bioanalytical chemistry》2008,391(2):661-669
A method based on anion exchange (AE) and affinity (AF)-HPLC (AE-AF-HPLC) hyphenated to inductively coupled plasma-(quadrupole)
mass spectrometry (ICP-QMS) was developed for the speciation analysis of selenoprotein P (SelP), glutathione peroxidase (GPx)
and selenoalbumin (SeAlb) in human serum. AE-HPLC is proposed here for the on-line alleviation of Cl and Br spectral interferences
on 77Se (40Ar37Cl) and 82Se (81Br1H). Separation of GPx, SelP and SeAlb by AE-AF-HPLC was obtained within a total chromatographic runtime of <20 min. On-line
(post-column) isotope dilution (ON-ID) and on-line external calibration (ON-EC)-ICP-QMS were used for the quantification of
Se in GPx, SelP and SeAlb. ON-EC using a Se-L-cystine standard was shown to be a suitable approach for the routine simultaneous speciation analysis of serum GPx, SelP
and SeAlb. The method validation was carried out by direct ICP-sector field MS determination of Se in GPx, SelP and SeAlb
fractions collected after AE-AF-HPLC separation. In addition, the method accuracy for the determination of total protein-bound
Se was assessed by analyzing a human serum reference material (BCR-637) certified for total Se content.
Figure A methodology for the alleviation of Cl and Br interferences in the accurate simultaneous speciation analysis of glutathione
peroxidase, selenoprotein P and selenoalbumin in human serum by affinity HPLC coupled on-line with ICP-quadrupole MS is proposed.
This approach may be particularly useful for clinical laboratories that only have an ICP-quadrupole MS without a collision
cell, or that lack an expensive ICP-SFMS (high-resolution) instrument 相似文献
194.
Balaj OP Semrouni D Steinmetz V Nicol E Clavaguéra C Ohanessian G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(15):4583-4592
The intrinsic folding of peptides about a sodium ion has been investigated in detail by using infrared multiple photon dissociation (IRMPD) spectroscopy and a combination of theoretical methods. IRMPD spectroscopy was carried out on sodiated polyglycines G(n)-Na(+) (n=2-8), in both the fingerprint and N-H/O-H stretching regions. Interplay between experimental and computational approaches (classical and quantum) enables us to decipher most structural details. The most stable structures of the small peptides up to G(6)-Na(+) maximize metal-peptide interactions with all peptidic C=O groups bound to sodium. In addition, direct interactions between peptide termini are possible for G(6)-Na(+) and larger polyglycines. The increased flexibility of larger peptides leads to more complex folding and internal peptide structuration through γ or β turns. A structural transition is found to occur between G(6)-Na(+) and G(7)-Na(+), leading to a structure with sodium coordination that becomes tri-dimensional for the latter. This transition was confirmed by H/D exchange experiments on G(n)-Na(+) (n=3-8). The most favorable hydrogen-bonding pattern in G(8)-Na(+) involves direct interactions between the peptide termini and opens the way to salt-bridge formation; however, there is only good agreement between experimental and computational data over the entire spectral range for the charge solvation isomer. 相似文献
195.
Zuzana Hricovíniová Milo? Hricovíni Ladislav Petru? 《Monatshefte für Chemie / Chemical Monthly》2001,13(2):731-737
D-Glycero-D-gulo-heptose reacted with 2,2-dimethoxypropane to give its 2,3:6,7-di-O-isopropylidene derivative. Its base-catalyzed addition
to formaldehyde resulted in the formation of 2,3:6,7-di-O-isopropylidene-2-C-(hydroxymethyl)-D-glycero-D-gulo-heptofuranose. After acid hydrolysis of this aldolization product, a new branched-chain aldose, 2-C-(hydroxymethyl)-D-glycero-D-gulo-heptose, was obtained, which was stereospecifically rearranged under the catalytic action of molybdic acid to D-glycero-D-ido-oct-2-ulose. 相似文献
196.
Georgiana Ioana Potra Cicalu Petru Aurel Babes Horia Calniceanu Adelina Popa Gabriela Ciavoi Gilda Mihaela Iova Mariana Ganea Ioana Scrobot 《Molecules (Basel, Switzerland)》2021,26(22)
Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes. 相似文献