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Author  |
Bykov, S.; Lednev, I.; Ianoul, A.; Mikhonin, A.; Munro, C.; Asher, S.A. |
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Title |
Steady-state and transient ultraviolet resonance Raman spectrometer for the 193-270 nm spectral region |
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Journal Article |
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Year |
2005 |
Publication |
Applied Spectroscopy |
Abbreviated Journal |
Appl Spectrosc |
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Volume |
59 |
Issue |
12 |
Pages |
1541-1552 |
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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 |
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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. |
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Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA |
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0003-7028 |
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PMID:16390595 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3767 |
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Author |
Dyson, H.J.; Beattie, J.K. |
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Title |
Spin state and unfolding equilibria of ferricytochrome c in acidic solutions |
Type |
Journal Article |
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Year |
1982 |
Publication |
The Journal of Biological Chemistry |
Abbreviated Journal |
J Biol Chem |
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Volume |
257 |
Issue |
5 |
Pages |
2267-2273 |
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Keywords |
Animals; *Cytochrome c Group; Electron Spin Resonance Spectroscopy; Heme; Horses; Hydrogen-Ion Concentration; Kinetics; Ligands; Myocardium; Protein Binding; Protein Conformation; Spectrophotometry; Temperature |
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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. |
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0021-9258 |
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PMID:6277891 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3807 |
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Author |
Gulotta, M.; Rogatsky, E.; Callender, R.H.; Dyer, R.B. |
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Title |
Primary folding dynamics of sperm whale apomyoglobin: core formation |
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Journal Article |
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Year |
2003 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
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Volume |
84 |
Issue |
3 |
Pages |
1909-1918 |
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Keywords |
Animals; Apoproteins/*chemistry; Crystallography/*methods; Horses; Myocardium/chemistry; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Species Specificity; Structure-Activity Relationship; Temperature; Whales |
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Abstract |
The structure, thermodynamics, and kinetics of heat-induced unfolding of sperm whale apomyoglobin core formation have been studied. The most rudimentary core is formed at pH(*) 3.0 and up to 60 mM NaCl. Steady state for ultraviolet circular dichroism and fluorescence melting studies indicate that the core in this acid-destabilized state consists of a heterogeneous composition of structures of approximately 26 residues, two-thirds of the number involved for horse heart apomyoglobin under these conditions. Fluorescence temperature-jump relaxation studies show that there is only one process involved in Trp burial. This occurs in 20 micro s for a 7 degrees jump to 52 degrees C, which is close to the limits placed by diffusion on folding reactions. However, infrared temperature jump studies monitoring native helix burial are biexponential with times of 5 micro s and 56 micro s for a similar temperature jump. Both fluorescence and infrared fast phases are energetically favorable but the slow infrared absorbance phase is highly temperature-dependent, indicating a substantial enthalpic barrier for this process. The kinetics are best understood by a multiple-pathway kinetics model. The rapid phases likely represent direct burial of one or both of the Trp residues and parts of the G- and H-helices. We attribute the slow phase to burial and subsequent rearrangement of a misformed core or to a collapse having a high energy barrier wherein both Trps are solvent-exposed. |
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Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA. gulotta@aecom.yu.edu |
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0006-3495 |
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PMID:12609893 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3783 |
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Author |
Hirota, S.; Suzuki, M.; Watanabe, Y. |
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Title |
Hydrophobic effect of trityrosine on heme ligand exchange during folding of cytochrome c |
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Journal Article |
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Year |
2004 |
Publication |
Biochemical and Biophysical Research Communications |
Abbreviated Journal |
Biochem Biophys Res Commun |
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Volume |
314 |
Issue |
2 |
Pages |
452-458 |
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Keywords |
Amino Acids/chemistry; Animals; Cytochromes c/*chemistry; Heme/*chemistry; Histidine/chemistry; Horses; Hydrogen-Ion Concentration; Kinetics; Ligands; Myocardium/chemistry; Peptides/chemistry; Protein Folding; Spectrophotometry; Spectrum Analysis, Raman; Tyrosine/*analogs & derivatives/*chemistry |
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Effect of a hydrophobic peptide on folding of oxidized cytochrome c (cyt c) is studied with trityrosine. Folding of cyt c was initiated by pH jump from 2.3 (acid-unfolded) to 4.2 (folded). The Soret band of the 2-ms transient absorption spectrum during folding decreased its intensity and red-shifted from 397 to 400 nm by interaction with trityrosine, whereas tyrosinol caused no significant effect. The change in the transient absorption spectrum by interaction with trityrosine was similar to that obtained with 100 mM imidazole, which showed that the population of the intermediate His/His coordinated species increased during folding of cyt c by interaction with trityrosine. The absorption change was biphasic, the fast phase (82+/-9s(-1)) corresponding to the transition from the His/H(2)O to the His/Met coordinated species, whereas the slow phase (24+/-3s(-1)) from His/His to His/Met. By addition of trityrosine, the relative ratio of the slow phase increased, due to increase of the His/His species at the initial stage of folding. According to the resonance Raman spectra of cyt c, the high-spin 6-coordinate and low-spin 6-coordinate species were dominated at pH 2.3 and 4.2, respectively, and these species were not affected by addition of trityrosine. These results demonstrated that the His/His species increased by interaction with trityrosine at the initial stage of cyt c folding, whereas the heme coordination structure was not affected by trityrosine when the protein was completely unfolded or folded. Hydrophobic peptides thus may be useful to study the effects of hydrophobic interactions on protein folding. |
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Address |
Department of Physical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, 607-8414 Kyoto, Japan. hirota@mb.kyoto-phu.ac.jp |
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0006-291X |
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PMID:14733927 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3777 |
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Author |
Miksovska, J.; Larsen, R.W. |
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Title |
Photothermal studies of pH induced unfolding of apomyoglobin |
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Journal Article |
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Year |
2003 |
Publication |
Journal of Protein Chemistry |
Abbreviated Journal |
J Protein Chem |
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Volume |
22 |
Issue |
4 |
Pages |
387-394 |
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Keywords |
Acoustics; Animals; Apoproteins/*chemistry/metabolism; Circular Dichroism; Horses; Myocardium/chemistry; Myoglobin/*chemistry/metabolism; Photolysis; Protein Conformation/radiation effects; Protein Denaturation/radiation effects; *Protein Folding; Temperature; Thermodynamics |
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Conformational dynamic and enthalpy changes associated with pH induced unfolding of apomyoglobin were studied using photoacoustic calorimetry and photothermal beam deflection methods. The transition between the native state and the I intermediate was induced by a nanosecond pH jump from o-nitrobenzaldehyde photolysis. Deconvolution of photoacoustic waves indicates two kinetic processes. The fast phase (T < 50 ns) is characterized by a volume expansion of 8.8 ml mol(-1). This process is followed by a volume contraction of about -22 ml mol(-1) (tau approximately 500 ns). Photothermal beam deflection measurements do not reveal any volume changes on the time scale between approximately 100 micros and 5 ms. We associate the volume contraction with structural changes occurring during the transition between the native state and the I intermediate. The lack of any processes on the ms time scale may indicate the absence of structural events involving larger conformational changes of apomyoglobin after the pH jump. |
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Department of Chemistry, University of South Florida, Tampa, Florida 33620, USA |
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ISSN |
0277-8033 |
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PMID:13678303 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3780 |
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Author |
Saigo, S. |
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Title |
A transient spin-state change during alkaline isomerization of ferricytochrome c |
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Journal Article |
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Year |
1981 |
Publication |
Journal of Biochemistry |
Abbreviated Journal |
J Biochem (Tokyo) |
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89 |
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6 |
Pages |
1977-1980 |
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Animals; *Cytochrome c Group; Horses; Hydrogen-Ion Concentration; Isomerism; Kinetics; Myocardium/enzymology; Oxidation-Reduction; Spectrophotometry |
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Kinetic difference spectra during the alkaline isomerization of ferricytochrome c were obtained by the pH-jump method in the range of 540 to 655 nm. The spectrum of the transient intermediate, which appears during the course of the isomerization, was reproduced from the spectra. The intermediate showed an intense absorption band at 600 nm, indicating that it is a high spin or mixed spin species. This is in contrast to the stable neutral and alkaline forms which are low spin species. The transient spin-state change during the isomerization was also observed upon rapid oxidation of ferrocytochrome c at alkaline pH. |
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0021-924X |
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PMID:6270075 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3808 |
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Author |
Williams, D.O.; Boatwright, R.B.; Rugh, K.S.; Garner, H.E.; Griggs, D.M.J. |
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Title |
Myocardial blood flow, metabolism, and function with repeated brief coronary occlusions in conscious ponies |
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Journal Article |
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Year |
1991 |
Publication |
The American journal of physiology |
Abbreviated Journal |
Am J Physiol |
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Volume |
260 |
Issue |
1 Pt 2 |
Pages |
H100-9 |
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Keywords |
Animals; Consciousness/*physiology; Coronary Circulation/*physiology; Coronary Disease/pathology/*physiopathology; Disease Models, Animal; Hemodynamic Processes/physiology; Horses/*physiology; Hydrogen/metabolism; Lactates/metabolism; Myocardium/*metabolism/pathology; Norepinephrine/metabolism; Potassium/metabolism; Regional Blood Flow |
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Studies were performed in the conscious pony instrumented with a Doppler flow probe and hydraulic occluder on the left anterior descending coronary artery (LAD), sonomicrometry crystals and intraventricular micromanometer in the left ventricle, and catheters in the left atrium and anterior interventricular vein. Two-minute LAD occlusions were performed every 30 min continuously or during working hours. Data on release of catabolites (potassium, hydrogen ions, and lactate) and norepinephrine from the initially dysfunctional region were obtained periodically during a regimen of 445 +/- 56 occlusions in six animals. Regional myocardial blood flow was measured (microsphere method) before and after an occlusion regimen in four animals. Marked release of catabolites and norepinephrine from the initially dysfunctional region was noted in association with early occlusions when myocardial segment function was severely reduced. With further occlusions, release of these substances decreased while segment function improved. Blood flow was markedly decreased in the initially dysfunctional region during an early occlusion but was at the control level during a later occlusion. Although the metabolic findings are consistent with protection due to “ischemic preconditioning” and no increase in collateral perfusion, the inverse relationship noted between catabolite release and segment function is best explained by flow-dependent mechanisms. These results, together with the myocardial blood flow data, serve to validate a previous assumption that protection against regional myocardial dysfunction under these conditions is due to increased collateral perfusion. |
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Department of Physiology, University of Missouri, Columbia 65212 |
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0002-9513 |
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PMID:1992786 |
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no |
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Call Number |
refbase @ user @ |
Serial |
98 |
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Author |
Wilson, M.T.; Ranson, R.J.; Masiakowski, P.; Czarnecka, E.; Brunori, M. |
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Title |
A kinetic study of the pH-dependent properties of the ferric undecapeptide of cytochrome c (microperoxidase) |
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Journal Article |
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Year |
1977 |
Publication |
European Journal of Biochemistry / FEBS |
Abbreviated Journal |
Eur J Biochem |
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Volume |
77 |
Issue |
1 |
Pages |
193-199 |
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Keywords |
Animals; Cyanides; *Cytochrome c Group/metabolism; Ferric Compounds; Horses; Hydrogen-Ion Concentration; Imidazoles; Kinetics; Mathematics; Myocardium/enzymology; *Oligopeptides/metabolism; *Peptide Fragments/metabolism; Protein Binding; Spectrophotometry; Temperature |
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The ferric form of the haem undecapeptide, derived from horse cytochrome c by peptic digestion, undergoes at least three pH-induced transitions with pK values of 3.4, 5.8 and 7.6. Temperature-jump experiments suggest that the first of these is due to the binding of a deprotonated imidazole group to the feric iron while the second and third arise from the binding of the two available amino groups present (the alpha-NH2 of valine and the epsilon-NH2 of lysine). Molecular models indicate that steric retraints on the peptide dictate that these amino groups may only coordinate to iron atoms via intermolecular bonds, thus leading to the polymerization of the peptide. Cyanide binding studies are in agreement with these conclusions and also yield a value of 3.6 X 10(6) M-1 s-1 for the intrinsic combination constant of CN- anion with the haem. A model is proposed which describes the pH-dependent properties of the ferric undecapeptide. |
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0014-2956 |
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PMID:20304 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3814 |
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