Spectroscopic study

In this study, we present the technique of tunable diode laser spectroscopy and the spectroscopic parameters of 13 lines of H2O in the 11980 -12260 cm−1 spectral region. Spectra were recorded at room temperature for a wide range of pressures (2 - 15 Torr for pure H2O and 50 - 760 Torr for H2O in air).

8p tamynhan5 10-12-2020 27 3   Download

Study on the chemical constituents of methanol extract from leaves of Moringa oleifera Lam. (Moringaceae) has resulted in the isolation of four compounds: Vitexin, isoquercitrin, tricosanol and tetradecanoic acid. Their structures were determined by spectroscopic methods.

5p tamynhan9 02-12-2020 27 3   Download

Molecular crystals are characterized by strong intramolecular forces and much weaker intermolecular forces. High-pressure spectroscopic studies provide useful data for refining the various model potentials which are used to predict of the physical properties of such systems as well as for the formation of various crystalline phases.

7p tamynhan8 04-11-2020 16 2   Download

Two heterocyclic oximes (E)-N-hydroxy-1-(pyridin-2-yl)methanimine (Hp2ylm) and (E)-N-hydroxy-1-(pyridin-3-yl)methanimine (Hp3ylm) were synthesized from pyridine-2-carbaldehyde and pyridine-3-carbaldehyde, respectively.

12p tocectocec 25-05-2020 9 2   Download

A group of new fluoroaniline Schiff bases (3a–3f) were synthesized and structurally characterized by various spectroscopic techniques such as 1H-NMR, LC-MS and FT-IR spectral studies.

8p tocectocec 25-05-2020 14 1   Download

Bài báo trình bày các kết quả tổng hợp và nghiên cứu cấu trúc của phức chất trans- [PtCl2(Meteug)(2-NH2C5H4N)] bằng phương pháp phổ IR, 1H NMR và đặc biệt là phương pháp nhiễu xạ tia X đơn tinh thể. Kết quả cho thấy 2-aminopyridine phối trí với Pt(II) qua nguyên tử N trong vòng pyridine, trong khi đó methyeugenoxyaxetat (Meteug) phối trí qua liên kết đôi của nhánh allyl. Mời tham khảo để biết thêm chi tiết.

6p estupendo5 31-08-2016 44 5   Download

Six new benzopyran derivatives were synthesized by reduction reaction and Michael reaction from malloapelta B.

5p uocvong04 24-09-2015 44 3   Download

Two eudesmane derivatives 3
-angeloyloxy-4
-acetoxy-7,11-dehydroeudesmane-8-one, 3
- angeloyloxy-4
-acetoxy-6,7-dehydroeudesmane-11-hydroperoxy-8-one have been isolated from the n-hexane extract of Grangea maderaspatana L. Poir collected in Vietnam, besides stigmasterol, taraxasterol and taraxasteryl acetate. Their structures were deduced from spectroscopic studies, including 2D-shift correlation COSY, DEPT, HMQC, HMBC-NMR experiments.

5p uocvong04 24-09-2015 45 5   Download

Two new aloceramides alomacrorrhiza A and alomacrorrhiza B were isolated from the ethanolic extract of the plant Alocasia macrorrhiza (L.) Schott. Their chemical structures were elucidated as (2S,3S,4R)-2N-[(2'R)-2'-hydroxy-hexacosanoyl]-tetradecane-1,3,4-triol (1) and (2S,3S,4R)-2N-[(2'R)-2'-hydroxy-hexacosanoyl]-hexadecane-1,3,4-triol (2) based on extensive 1D, 2D NMR, EI-MS, FAB-MS, HR-FAB-MS spectroscopic data and chemical degradation studies.

4p uocvong04 24-09-2015 30 3   Download

Angelica sinensis (OLiv.) Diels ("Danggui") belongs to the family Umbelliferae. Its rhizomes are reputed to have marked restorative, antianaemic and haemagogic properties. From ethyl acetate and butanol extracts of rhizomes of this plant 8 nitrogen-containing compounds (1-8) have been isolated. Their structures were elucidated by means of MS and NMR spectroscopic methods as 5-oxo-proline, 5-oxo-prolin-ethylester, nicotinamide, tryptophane, perlolidine, 1,2,3,4-tetrahydro-1-methyl- -carboline-3-carboxylic acide, adenosine and uridine.

6p uocvong04 24-09-2015 49 3   Download

A flavonol glycoside, kaempferol 3-O- -sambubioside (1) was isolated in a study on the polar constituents of the buds of Rhodomyrtus tomentosa Ait. Hassk. (Myrtaceae). Its structure was determined by spectroscopic methods.

3p uocvong04 24-09-2015 34 4   Download

The dinitrogenase component proteins of the conventional Mo nitrogenase (MoFe protein) and of the alternative Fe-only nitrogenase (FeFe protein) were both isolated and purified from Rhodobacter capsulatus, redox-titrated according to the same procedures and subjected to an EPR spectroscopic comparison. In the course of an oxidative titration of the MoFe protein (Rc1Mo) three significant S ¼ 1/2 EPR signals deriving from oxidized states of the P-cluster were detected: (1) a rhombic signal (g ¼ 2.07, 1.96 and 1.

12p system191 01-06-2013 31 4   Download

A clear difference in the enthalpy changes derived from spectroscopic and calorimetric measurements has recently been shown. The exact interpretation of this deviation varied from study to study, but it was generally attributed to the non-two-state transition and heat capacity change. Although the temperature-dependent thermodynamics of the duplex formation was often implied, systemic and extensive studies have been lacking in universally assigning the appropriate thermodynamic parameter sets.

10p system191 01-06-2013 36 4   Download

Department of Chemistry ‘IFM’, University of Torino, Italy; 2Department of Biology, University ‘Roma Tre’, Rome, Italy; 3Department of Structural and Functional Biology, University of Insubria, Italy Haem binding to human serum albumin (HSA) endows the protein with peculiar spectroscopic properties. Here, the effect of ibuprofen and warfarin on the spectroscopic properties of ferric haem –human serum albumin (ferric HSA–haem) and of ferrous nitrosylated haem –human serum albumin (ferrous HSA –haem-NO) is reported.

7p system191 01-06-2013 46 3   Download

A comparative study of thermodynamic and kinetic aspects of Cu(II) and Ni(II) binding at the N-terminal binding site of human and bovine serum albumins (HSA and BSA, respectively) and short peptide analogues was performed using potentiometry and spectroscopic techniques. It was found that while qualitative aspects of interaction (spectra and structures of complexes, order of reactions) could be reproduced, the quantitative parameters (stability and rate constants) could not.

9p research12 01-06-2013 38 4   Download

Thecaa3-oxidase from Thermus thermophilushas been studied with a combined electrochemical, UV/VIS and Fourier-transform infrared (FT-IR) spectroscopic approach. In this oxidase the electron donor, cytochromec, is covalently bound to subunit II of the cytochrome c oxidase. Oxidative electrochemical redox titrations in the visible spectral range yielded a midpoint potential of )0.01 ± 0.01 V (vs. Ag/AgCl/3MKCl, 0.218 V vs. SHE¢) for the hemec.

9p research12 29-04-2013 49 3   Download

Small-angle neutron scattering experiments were performed on horse azidometmyoglobin (MbN3) at pressures up to 300 MPa.Other spectroscopic techniques have shown that a reorganization of the secondary structure and of the active site occur in this pressure range. The present measurements, performedusingvarious concentrations ofMbN3, showthat the compactness of the protein is not altered as the value of its radius of gyration remains constant up to 300 MPa.

7p research12 23-04-2013 54 3   Download

Mature, active mammalian histidine decarboxylase is a di-meric enzyme of carboxy-truncatedmonomers (
53 kDa). By using a biocomputational approach, we have generateda three-dimensional model of a recombinant 1/512 fragment of the rat enzyme, which shows kinetic constants similar to those of the mature enzyme purified from rodent tissues. This model, together with previous spectroscopic data, al-lowed us to postulate that the occupation of the catalytic center by the natural substrate, or by substrate-analogs, would induce remarkable changes in the conformation of the intact holoenzyme....

12p tumor12 20-04-2013 36 2   Download

The major cellulase secreted by the filamentous fungus Trichoderma reeseiis cellobiohydrolase Cel7A. Its three-dimensional structure has been solved and various mutant enzymes produced. In order to study the potential use of T. reeseiCel7A in the alkaline pHrange, the thermal sta-bilityofCel7Awas studiedas a functionof pHwith thewild-type and two mutant enzymes using different spectroscopic methods. Tryptophan fluorescence and CD measurements of the wild-type enzyme show an optimal thermostability between pH3.5–5.

8p tumor12 20-04-2013 39 4   Download

Specific lipids of the purple membrane ofHalobacteriaare required for normal bacteriorhodopsin structure, function, and photocycle kinetics [Hendler, R.W. & Dracheva, S. (2001) Biochemistry (Moscow)66, 1623–1627]. The decay of the M-fast intermediate through a path including the O intermediate requires the presence of a hydrophobic envi-ronment near four charged aspartic acid residues within the cytoplasmic loop region of the protein (R. W. Hendler & S. Bose, unpublished results).

6p fptmusic 16-04-2013 33 2   Download