| |
Records |
Links |
|
Author |
Dyson, H.J.; Beattie, J.K. |
|
| |
Title  |
Spin state and unfolding equilibria of ferricytochrome c in acidic solutions |
Type |
Journal Article |
| |
Year |
1982 |
Publication |
The Journal of Biological Chemistry |
Abbreviated Journal |
J Biol Chem |
|
| |
Volume |
257 |
Issue |
5 |
Pages |
2267-2273 |
|
| |
Keywords |
Animals; *Cytochrome c Group; Electron Spin Resonance Spectroscopy; Heme; Horses; Hydrogen-Ion Concentration; Kinetics; Ligands; Myocardium; Protein Binding; Protein Conformation; Spectrophotometry; Temperature |
|
| |
Abstract |
Equilibrium, stopped flow, and temperature-jump spectrophotometry have been used to identify processes in the unfolding of ferricytochrome c in acidic aqueous solutions. A relaxation occurring in approximately 100 microseconds involves perturbation of a spin-equilibrium between two folded conformers of the protein with methionine-80 coordinated or dissociated from the heme iron. The protein unfolds more slowly, in milliseconds, with dissociation and protonation of histidine-18. These two transitions appear cooperative in equilibrium measurements at low (0.01 M) ionic strength, but are separated at higher (0.10 M) ionic strength. They are resolved under both conditions in the dynamic measurements. The spin-equilibrium description permits a unified explanation of a number of properties of ferricytochrome c in acidic aqueous solutions. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
English |
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0021-9258 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
PMID:6277891 |
Approved |
no |
|
| |
Call Number |
Equine Behaviour @ team @ |
Serial |
3807 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Bykov, S.; Lednev, I.; Ianoul, A.; Mikhonin, A.; Munro, C.; Asher, S.A. |
|
| |
Title |
Steady-state and transient ultraviolet resonance Raman spectrometer for the 193-270 nm spectral region |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Applied Spectroscopy |
Abbreviated Journal |
Appl Spectrosc |
|
| |
Volume |
59 |
Issue |
12 |
Pages |
1541-1552 |
|
| |
Keywords |
Animals; Equipment Design; Equipment Failure Analysis; Horses; Kinetics; Metmyoglobin/*analysis; Myocardium/*metabolism; Reproducibility of Results; Sensitivity and Specificity; Spectrophotometry, Ultraviolet/*instrumentation/methods; Spectrum Analysis, Raman/*instrumentation/methods |
|
| |
Abstract |
We describe a state-of-the-art tunable ultraviolet (UV) Raman spectrometer for the 193-270 nm spectral region. This instrument allows for steady-state and transient UV Raman measurements. We utilize a 5 kHz Ti-sapphire continuously tunable laser (approximately 20 ns pulse width) between 193 nm and 240 nm for steady-state measurements. For transient Raman measurements we utilize one Coherent Infinity YAG laser to generate nanosecond infrared (IR) pump laser pulses to generate a temperature jump (T-jump) and a second Coherent Infinity YAG laser that is frequency tripled and Raman shifted into the deep UV (204 nm) for transient UV Raman excitation. Numerous other UV excitation frequencies can be utilized for selective excitation of chromophoric groups for transient Raman measurements. We constructed a subtractive dispersion double monochromator to minimize stray light. We utilize a new charge-coupled device (CCD) camera that responds efficiently to UV light, as opposed to the previous CCD and photodiode detectors, which required intensifiers for detecting UV light. For the T-jump measurements we use a second camera to simultaneously acquire the Raman spectra of the water stretching bands (2500-4000 cm(-1)) whose band-shape and frequency report the sample temperature. |
|
| |
Address |
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA |
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
English |
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0003-7028 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
PMID:16390595 |
Approved |
no |
|
| |
Call Number |
Equine Behaviour @ team @ |
Serial |
3767 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Rodier, F. |
|
| |
Title |
[Spectral properties of porcine plasminogen: study of the acidic transition (author's transl)] |
Type |
Journal Article |
| |
Year |
1976 |
Publication |
European journal of biochemistry / FEBS |
Abbreviated Journal |
Eur J Biochem |
|
| |
Volume |
63 |
Issue |
2 |
Pages |
553-562 |
|
| |
Keywords |
Animals; Binding Sites; Guanidines; Hydrogen-Ion Concentration; *Plasminogen; Protein Binding; Protein Conformation; Spectrometry, Fluorescence; Spectrophotometry; Spectrophotometry, Ultraviolet; Swine; Temperature |
|
| |
Abstract |
The acidic transition of porcine plasminogen, prepared by affinity chromatography, was studied by non-destructive methods. These methods are based on the analysis of the behaviour of the tryptophyls under various conditions. The perturbation of the absorption and emission spectra by pH or temperature and the dynamic quenching of the intrinsic fluorescence are used to obtain information on structural changes which affect the environment of these residues. It is shown that by decreasing pH the fluorescence emission spectra are shifted toward the long wavelengths, with a broadening of the fluorescence band. The same effect can be obtained at constant pH by heating the protein solution. In order to analyze these phenomena, it is assumed that the fluorescence intensities at 355 nm and 328 nm reflect the proportion of the tryptophans which are exposed to the solvent, and buried, respectively. The plot of the ratio of the fluorescence intensities at these wavelengths versus pH or temperature leads to a titration curve showing an unmasking of tryptophans. The proportion of exposed tryptophans is measured by the dynamic fluorescence quenching technique and the data analyzed according to Lehrer. The plot of the fraction of exposed tryptophyls versus pH also shows the unmasking of these chromophores. Thermal perturbation of a solution of plaminogen at neutral pH induces a difference absorption spectrum whose amplitudes at the maxima are proportional to the number of exposed aromatic residues. The comparison with a solution of fully denatured plasminogen in 6 M guanidium chloride, where all the tryptophyls are exposed, shows that the percentage of exposure is equal to 59%. This number is significantly higher than the percentage found by the fluorescence quenching technique (20%), indicating that some tryptophyls are located in crevices, exposed to the solvent but not to the iodide. At acidic pH the absorption difference spectra induced by thermal perturbation are not classical, since they show an inversion and a new band between 300 nm and 305 nm. This band is mentioned in the literature as a minor band of tryptophan which appears when this chromophore is located in an asymmetric environment. On plotting the maximum amplitude of these spectra obtained at acidic pH versus temperature, we obtain a curve indicating that two types of antagonistic interactions are involved in the perturbation of the chromophores spectra. The spectrophotometric titration of plasminogen gives classical absorption difference spectra. By plotting the maximum amplitude at 292 nm versus pH, we obtain a titration curve with an apparent pK of 2.9 units. This pK is acidic which respect to the pK value of a normal carboxyl. This low value can be due to a positively charged group in the neighbourhood of a carboxyl, which interacts with one or more chromophores. When the carboxyl becomes protonated, this positively charged group is free and available to perturb the environment of some chromophores... |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
French |
Summary Language |
|
Original Title |
Proprietes spectrales du plasminogene porcin. Etude de la transition acide |
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0014-2956 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
PMID:4326 |
Approved |
no |
|
| |
Call Number |
Admin @ knut @ |
Serial |
22 |
|
| Permanent link to this record |
