Circular dichroism

Xem 1-20 trên 26 kết quả Circular dichroism
  • During the years surrounding the new millennium, the field of vibrational optical activity (VOA), comprised principally of vibrational circular dichroism (VCD) and vibrational Raman optical activity (ROA), underwent a transition from a specialized area of research that had been practiced by a handful of pioneers into an important newfield of spectroscopy practiced by an increasing number of scientists worldwide. This transition was made possible by the development of commercial instrumentation and software for the routine measurement and quantum chemical calculation ofVOA.

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  • Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: " Homonuclear 1H NMR and circular dichroism study of the HIV-1 Tat Eli variant...

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  • Chirality is a phenomenon that is manifested throughout the natural world, ranging from fundamental particles through the realm of molecules and biological organisms to spiral galaxies. Thus, chirality is of interest to physicists, chemists, biologists, and astronomers. Chiroptical spectroscopy utilizes the differential response of chiral objects to circularly polarized electromagnetic radiation. Applications of chiroptical spectroscopy are widespread in chemistry, biochemistry, biology, and physics. It is indispensable for stereochemical elucidation of organic and inorganic molecules.

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  • We have used the circular dichroismand infrared spectra of a specially designed 50 protein database [Oberg, K.A., Ruysschaert, J.M. & Goormaghtigh, E. (2003)Protein Sci. 12, 2015–2031] in order to optimize the accuracy of spectroscopic protein secondary structure determination using multivariate statisticalanalysis methods. The results demonstrate that when the proteins are carefully selected for the diversity in their structure, no smaller subset of the database contains the necessary information to describe the entire set....

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  • Physical chemistry of macromolecules is a course that is frequently offered in the biochemistry curriculum of a college or university. Occasionally, it is also offered in the chemistry curriculum. When it is offered in the biochemistry curriculum, the subject matter is usually limited to biological topics and is identical to biophysical chemistry. When it is offered in the chemistry curriculum, the subject matter is often centered around synthetic polymers and the course is identical to physical polymer chemistry.

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  • Biology is chemistry on an impressive scale. It is a product of evolution, the outcome of countless random experiments, resulting in the exquisite complexity of the biological world of which we are a part. Setting aside any philosophical considerations, living organisms - including ourselves - are simply nothing more than wet, floppy bags of chemistry: complicated mixtures of molecules interacting in a multitude of ways. All this takes place mainly in ...

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  • Thermodynamic parameters describing the conformational stability of the histidine-containing phosphocarrier protein fromStreptomyces coelicolor, scHPr, have been determined by steady-state fluorescence measurements of isothermal urea-denaturations, differential scanning calorimetry at different guanidinium hydrochloride concentrations and, independently, by far-UV circular dichroism measurements of isothermal urea-denaturations, and thermal denatura-tions at fixed urea concentrations.

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  • Tham khảo sách 'comprehensive chiroptical spectroscopy volume 1', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • Circular dichroism (CD) spectra of two major hemoglobin components (Hb), HbI and HbIV, from Oncorhyncus mykiss(formerly Salmo irideus) trout were evaluated in the range 250–600 nm. HbI is characterized by a complete insensitivity to pH changes, while HbIV presents the Root effect. Both reduced [iron(II) or oxy] and oxidized (met) forms of the two proteins were studied at different pHs, 7.8 and 6.0, to obtain information about the pH effects on the structural features of these hemoglobins.

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  • The effect of pH and temperature on structure, stability, activity and enantioselectivity of haloalkane dehalogenase DbjA from Bradyrhizobium japonicum USDA110 was investigated in this study. Conformational changes have been assessed by circular dichroism spectroscopy, functional changes by kinetic analysis, while quaternary structure was studied by gel filtration chromatography.

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  • The thermal denaturation of endo-b-1,3-glucanase from the hyperthermo-philic microorganismPyrococcus furiosuswas studied by calorimetry. The calorimetric profile revealed two transitions at 109 and 144C, correspond-ing to protein denaturation and complete unfolding, respectively, as shown by circular dichroism and fluorescence spectroscopy data.

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  • Vertebrate metallothioneins are found to contain Zn(II) and variable amounts of Cu(I),in vivo, and are believed to be important for d 10 -metal control. To date, structural information is available for the Zn(II) and Cd(II) forms, but not for the Cu(I) or mixed metal forms. Cu(I) binding to metallothionein-1 has been investigated by circular dichroism, luminescence and 1 H NMR using two synthetic fragments representing thea- and the b-domain.

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  • We used differential scanning calorimetry (DSC) and circular dichroism (CD) to investigate thermal unfolding of recombinant fibroblast isoforms ofa-tropomyosin (Tm) in comparison with that of smooth muscle Tm. These two nonmuscle Tm isoforms 5a and 5b differ internally only by exons 6b⁄6a, and they both differ from smooth muscle Tm by the N-terminal exon 1b which replaces the muscle-specific exons 1a and 2a.

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  • Poneratoxin is a small neuropeptide found in the venom of the antParaponera clavata. It is stored in the venom reservoir as an inactive 25-residue peptide. Here we des-cribe both chemically synthesized poneratoxin and pon-eratoxin obtained by expression in insect cells. When expressed in insect cells, poneratoxin was observed attached to cell membranes. Both synthetic and recom-binant ponerotoxins were soluble below pH 4.5. The structure of synthetic poneratoxin was characterized by circular dichroism and solved by nuclear magnetic reso-nance. ...

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  • The folding of a 93-residue protein, the histidine-phospho-carrier protein ofStreptomyces coelicolor,HPr,hasbeen studied using several biophysical techniques, namely fluo-rescence, 8-anilinonaphthalene-1-sulfate binding, circular dichroism, Fourier transform infrared spectroscopy, gel filtration chromatography and differential scanning calori-metry. The chemical-denaturation behaviour of HPr, fol-lowed by fluorescence, CD and gel filtration, at pH 7.5 and 25C, is described as a two-state process, which does not involve the accumulation of thermodynamically stable intermediates.

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  • High hydrostatic pressure induced cold inactivation of carboxypeptidase Y. Carboxypeptidase Y was fully active when exposed to subzero temperature at 0.1 MPa; however, the enzyme became inactive when high hydrostatic pressure and subzero temperature were both applied. When the enzyme was treated at pressures higher than 300 MPa and temperatures lower than)5C, it underwent an irreversible inactivation in which nearly 50% of the a-helical structure was lost as judged by circular dichroism spectral analysis....

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  • With the aim to distinguish between local and global conformational changes induced by trifluoroethanol in RNase A, spectroscopic and activity measurements in combination with proteolysis by unspecific proteases have been exploited for probing structural transitions of RNase A as a function of trifluoroethanol concentration. At 30% (v/v) trifluoroethanol (pH 8.0; 25 °C), circular dichroism and fluorescence spectroscopy indicate a cooperative collapse of the tertiary structure of RNase A coinciding with the loss of its enzymatic activity....

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  • Porcine heart cytoplasmic malate dehydrogenase (s-MDH) is a dimeric protein (2 · 35 kDa). We have studied equilibrium unfolding and refolding of s-MDH using activity assay, fluorescence, far-UV and near-UV circular dichroism (CD) spectroscopy, hydrophobic probe-1-anilino8-napthalene sulfonic acid binding, dynamic light scattering, and chromatographic (HPLC) techniques. The unfolding and refolding transitions are reversible and show the presence of two equilibrium intermediate states.

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  • Shikimate kinase was chosen as a convenient representative example of the subclass of a/b proteins with which to examine the mechanism of protein folding. In this paper we report on the refolding of the enzyme after denaturation in urea. As shown by the changes in secondary and tertiary structure monitored by far UV circular dichroism (CD) and fluorescence, respectively, the enzyme was fully unfolded in 4 M urea. From an analysis of the unfolding curve in terms of the two-state model, the stability of the folded state could be estimated as 17 kJÆmol)1.

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  • Assembly of FtsZ was completely inhibited by low concentrations of urea and its unfolding occurred in two steps in the presence of urea, with the formation of an intermediate [Santra MK & Panda D (2003) J Biol Chem 278, 21336–21343]. In this study, using the fluorescence of 1-anilininonaph-thalene-8-sulfonic acid and far-UV circular dichroism spectroscopy, we found that a natural osmolyte, trimethylamine N-oxide (TMAO), counter-acted the denaturing effects of urea and guanidium chloride on FtsZ....

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