| Records |
| Author |
Ballew, R.M.; Sabelko, J.; Gruebele, M. |
| Title |
Direct observation of fast protein folding: the initial collapse of apomyoglobin |
Type |
Journal Article |
| Year |
1996 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
93 |
Issue |
12 |
Pages |
5759-5764 |
| Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Horses; Kinetics; Muscle, Skeletal/chemistry; Myoglobin/*chemistry; *Protein Folding; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Temperature |
| Abstract |
The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse. |
| Address |
School of Chemical Sciences and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, 61801, USA |
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| Language |
English |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0027-8424 |
ISBN |
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Expedition |
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Conference |
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| Notes |
PMID:8650166 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3798 |
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| Author |
Chiba, K.; Ikai, A.; Kawamura-Konishi, Y.; Kihara, H. |
| Title |
Kinetic study on myoglobin refolding monitored by five optical probe stopped-flow methods |
Type |
Journal Article |
| Year |
1994 |
Publication |
Proteins |
Abbreviated Journal |
Proteins |
| Volume |
19 |
Issue |
2 |
Pages |
110-119 |
| Keywords |
Animals; Chromatography, Gel; Circular Dichroism; Horses; Kinetics; Metmyoglobin/analogs & derivatives/chemistry; Myoglobin/*chemistry; *Protein Folding; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Urea |
| Abstract |
The refolding kinetics of horse cyanometmyoglobin induced by concentration jump of urea was investigated by five optical probe stopped-flow methods: absorption at 422 nm, tryptophyl fluorescence at around 340 nm, circular dichroism (CD) at 222 nm, CD at 260 nm, and CD at 422 nm. In the refolding process, we detected three phases with rate constants of > 1 x 10(2) s-1, (4.5-9.3) s-1, and (2-5) x 10(-3) s-1. In the fastest phase, a substantial amount of secondary structure (approximately 40%) is formed within the dead time of the CD stopped-flow apparatus (10.7 ms). The kinetic intermediate populated in the fastest phase is shown to capture a hemindicyanide, suggesting that a “heme pocket precursor” recognized by hemindicyanide must be constructed within the dead time. In the middle phase, most of secondary and tertiary structures, especially around the captured hemindicyanide, have been constructed. In the slowest phase, we detected a minor structural rearrangement accompanying the ligand-exchange reaction in the fifth coordination of ferric iron. We present a possible model for the refolding process of myoglobin in the presence of the heme group. |
| Address |
Laboratory of Biodynamics, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Kanagawa, Japan |
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| Language |
English |
Summary Language |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0887-3585 |
ISBN |
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Conference |
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| Notes |
PMID:8090705 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3799 |
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| Author |
Steinhoff, H.J.; Schrader, J.; Schlitter, J. |
| Title |
Temperature-jump studies and polarized absorption spectroscopy of methemoglobin-thiocyanate single crystals |
Type |
Journal Article |
| Year |
1992 |
Publication |
Biochimica et Biophysica Acta |
Abbreviated Journal |
Biochim Biophys Acta |
| Volume |
1121 |
Issue |
3 |
Pages |
269-278 |
| Keywords |
Animals; Crystallization; Horses; Kinetics; Methemoglobin/*chemistry; Solutions; Spectrum Analysis; Temperature; Thiocyanates/*chemistry |
| Abstract |
Association equilibria and association kinetics of the thiocyanate binding reaction to methemoglobin in single crystals and solution are studied using temperature-jump technique and polarized absorption spectroscopy. Different kinetic constants are found for the reaction in solution and crystal phase for the alpha- and beta-subunits of the methemoglobin tetramer. The reduction of the reactivity of the alpha- and beta-subunits in crystalline phase is 6-fold and 2.4-fold, respectively, compared to the values found in solution. The intramolecular binding reaction of the N epsilon of the distal histidine E7 which is observed in methemoglobin in solution cannot be detected in single crystals. Our results suggest that crystallization of hemoglobin has little influence on small-scale structural fluctuations which are necessary for ligands to get to the binding sites and large-scale structural motions are suppressed. |
| Address |
Institut fur Biophysik, Ruhr-Universitat Bochum, Germany |
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Place of Publication |
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| Language |
English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0006-3002 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
PMID:1627604 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3800 |
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| Author |
Jablonska, E.M.; Ziolkowska, S.M.; Gill, J.; Szykula, R.; Faff, J. |
| Title |
Changes in some haematological and metabolic indices in young horses during the first year of jump-training |
Type |
Journal Article |
| Year |
1991 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
Equine Vet J |
| Volume |
23 |
Issue |
4 |
Pages |
309-311 |
| Keywords |
Alanine Transaminase/blood; Animals; Bicarbonates/blood; Blood Glucose/analysis; Blood Proteins/analysis; Breeding; Carbon Dioxide/blood; Exercise Test/veterinary; Fatty Acids, Nonesterified/blood; Female; Fructose-Bisphosphate Aldolase/blood; Hematocrit/veterinary; Hemoglobins/analysis; Horses/*blood/metabolism; Hydrogen-Ion Concentration; Lactates/blood; Male; Oxygen/blood; *Physical Conditioning, Animal; Pyruvates/blood |
| Abstract |
Effects of an 18 min exercise test, on three separate occasions during a one year jump-training programme, was studied in seven horses. Determinations were carried out on venous blood for packed cell volume, haemoglobin, total protein, lactate and pyruvate, glucose, free fatty acids, insulin, glucagon, blood gases, bicarbonate, pH, aldolase, aspartate aminotransferase and alanine amino-transferase. Exercise caused a slight increase in lactate and pyruvate, total protein, aldolase, alanine aminotransferase, pO2, bicarbonate and pH. Glucose, free fatty acids and pCO2 levels decreased. Training caused no significant difference in these changes. However, during the year, increases in lactate and decreases in pH (resting levels) were observed. |
| Address |
Department of Vertebrate Animal Physiology, Warszawa, Poland |
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English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0425-1644 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
PMID:1915234 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3801 |
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| Author |
Hinrichs, K.; Watson, E.D.; Kenney, R.M. |
| Title |
Granulosa cell tumor in a mare with a functional contralateral ovary |
Type |
Journal Article |
| Year |
1990 |
Publication |
Journal of the American Veterinary Medical Association |
Abbreviated Journal |
J Am Vet Med Assoc |
| Volume |
197 |
Issue |
8 |
Pages |
1037-1038 |
| Keywords |
Animals; Corpus Luteum/*physiopathology; Female; Granulosa Cell Tumor/pathology/physiopathology/*veterinary; Horse Diseases/*pathology/physiopathology; Horses; Ovarian Neoplasms/pathology/*veterinary; Ovary/*pathology/physiopathology |
| Abstract |
A functional corpus luteum was found in the ovary contralateral to the ovary with a granulosa cell tumor in a 24-year-old Standardbred mare. The mare was ovariectomized because she was to be used as a jump mare for collection of semen from stallions. The blood concentration of progesterone was 2.2 ng/ml, and the luteal tissue progesterone concentration was 6.3 micrograms/mg. Atrophy of the contralateral ovary is one of the major signs used in diagnosis of granulosa cell tumor; however, our findings indicate that the ovary contralateral to a granulosa cell tumor is not invariably nonfunctional. |
| Address |
Department of Medicine, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536 |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0003-1488 |
ISBN |
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Medium |
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Conference |
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| Notes |
PMID:2243036 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3802 |
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| Author |
Steinhoff, H.J.; Lieutenant, K.; Redhardt, A. |
| Title |
Conformational transition of aquomethemoglobin: intramolecular histidine E7 binding reaction to the heme iron in the temperature range between 220 K and 295 K as seen by EPR and temperature-jump measurements |
Type |
Journal Article |
| Year |
1989 |
Publication |
Biochimica et Biophysica Acta |
Abbreviated Journal |
Biochim Biophys Acta |
| Volume |
996 |
Issue |
1-2 |
Pages |
49-56 |
| Keywords |
Animals; Electron Spin Resonance Spectroscopy; Heme; Histidine; Horses; Humans; Hydrogen-Ion Concentration; Methemoglobin/*ultrastructure; Motion; Protein Conformation; Temperature; Thermodynamics; Water |
| Abstract |
Temperature-dependent EPR and temperature-jump measurements have been carried out, in order to examine the high-spin to low-spin transition of aquomethemogobin (pH 6.0). Relaxation rates and equilibrium constants could be determined as a function of temperature. As a reaction mechanism for the high-spin to low-spin transition, the binding of N epsilon of His E7 to the heme iron had been proposed; the same mechanism had been suggested for the ms-effect, found in temperature-jump experiments on aquomethemoglobin. A comparison of the thermodynamic quantities, deduced form the measurements in this paper, gives evidence that indeed the same reaction is investigated in both cases. Our results and most of the findings of earlier studies on the spin-state transitions of aquomethemoglobin, using susceptibility, optical, or EPR measurements, can be explained by the transition of methemoglobin with H2O as ligand (with high-spin state at all temperatures) and methemoglobin with ligand N epsilon of His E7 (with a low-spin ground state). Thermal fluctuations of large amplitude have to be postulated for the reaction to take place, so this reaction may be understood as a probe for the study of protein dynamics. |
| Address |
Institut fur Biophysik, Ruhr-Universitat Bochum, F.R.G |
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Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0006-3002 |
ISBN |
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Conference |
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| Notes |
PMID:2544230 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3803 |
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| Author |
Steinhoff, H.J. |
| Title |
A continuous wave laser T-jump apparatus and its application to chemical reactions in hemoglobin single crystals |
Type |
Journal Article |
| Year |
1988 |
Publication |
Journal of Biochemical and Biophysical Methods |
Abbreviated Journal |
J Biochem Biophys Methods |
| Volume |
15 |
Issue |
6 |
Pages |
319-330 |
| Keywords |
Animals; Chemistry; Crystallization; *Heat; *Hemoglobins; Horses/blood; *Lasers; Methemoglobin; Solutions; Thermodynamics; Thiocyanates |
| Abstract |
A laser temperature jump apparatus is constructed where the T-jump is achieved by means of the direct absorption of continuous laser radiation of low intensity by a solid sample. The final temperature in the irradiated volume element is reached when the absorbed radiation power equals the dissipation of heat by heat conduction. The time range from the beginning of irradiation to the stationary state depends on the geometry of the irradiated volume element and is less than 10 ms. The heating laser beam is simultaneously used to detect the relaxation to the new chemical equilibrium in the sample. Relaxation processes with relaxation rates between 10(2) s-1 and less than 10(-3) s-1 on samples with volumes less than 10(-3) mm3 may be investigated using this T-jump method. One application of this method is the determination of reaction rates of ligand reactions in hemoglobin single crystals. Rate constants obtained for the reaction of thiocyanate with crystallized horse methemoglobin are presented. |
| Address |
Institut fur Biophysik, Ruhr-Universitat Bochum, F.R.G |
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| Language |
English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0165-022X |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
PMID:3379245 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3804 |
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| Author |
Gonzalez-Fernandez, J.M.; Atta, S.E. |
| Title |
Facilitated transport of oxygen in the presence of membranes in the diffusion path |
Type |
Journal Article |
| Year |
1982 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
| Volume |
38 |
Issue |
2 |
Pages |
133-141 |
| Keywords |
Animals; Biological Transport, Active; Cell Membrane/*metabolism; Diffusion; Dogs; Horses; Humans; Kinetics; Mathematics; *Models, Biological; Muscles/*metabolism; Oxygen/*metabolism |
| Abstract |
Most of the experimental observations on facilitated transport have been done with millipore filters, and all the theoretical studies have assumed homogeneous spatial properties. In striated muscle there exist membranes that may impede the diffusion of the carrier myoglobin. In this paper a theoretical study is undertaken to analyze the transport in the presence of membranes in the diffusion path. For the numerical computations physiologically relevant values of the parameters were chosen. The numerical results indicate that the presence of membranes tends to decrease the facilitation. For the nonlinear chemical kinetics of the reaction of oxygen with the carrier, this decrement also depends on the location of the membranes. At the higher oxygen concentration side of each membrane the flow of combined oxygen is transferred to the flow of dissolved oxygen. The reverse process occurs at the lower concentration side. Jump discontinuities of the concentration of the oxygen-carrier compound at each membrane are associated with these transfers. The decrement of facilitation is due to the cumulative effect of these jump discontinuities. |
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Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0006-3495 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
PMID:7093418 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3806 |
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| 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. |
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Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0021-9258 |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
PMID:6277891 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3807 |
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| Author |
Saigo, S. |
| Title |
A transient spin-state change during alkaline isomerization of ferricytochrome c |
Type |
Journal Article |
| Year |
1981 |
Publication |
Journal of Biochemistry |
Abbreviated Journal |
J Biochem (Tokyo) |
| Volume |
89 |
Issue |
6 |
Pages |
1977-1980 |
| Keywords |
Animals; *Cytochrome c Group; Horses; Hydrogen-Ion Concentration; Isomerism; Kinetics; Myocardium/enzymology; Oxidation-Reduction; Spectrophotometry |
| Abstract |
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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English |
Summary Language |
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Original Title |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
0021-924X |
ISBN |
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Expedition |
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Conference |
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| Notes |
PMID:6270075 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3808 |
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