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Author |
Steinhoff, H.J. |
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Title |
A continuous wave laser T-jump apparatus and its application to chemical reactions in hemoglobin single crystals |
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Journal Article |
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Year |
1988 |
Publication |
Journal of Biochemical and Biophysical Methods |
Abbreviated Journal |
J Biochem Biophys Methods |
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Volume |
15 |
Issue |
6 |
Pages |
319-330 |
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Keywords |
Animals; Chemistry; Crystallization; *Heat; *Hemoglobins; Horses/blood; *Lasers; Methemoglobin; Solutions; Thermodynamics; Thiocyanates |
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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. |
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Address |
Institut fur Biophysik, Ruhr-Universitat Bochum, F.R.G |
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English |
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Edition |
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ISSN |
0165-022X |
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Notes |
PMID:3379245 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3804 |
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Author |
Steinhoff, H.J.; Schrader, J.; Schlitter, J. |
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Title |
Temperature-jump studies and polarized absorption spectroscopy of methemoglobin-thiocyanate single crystals |
Type |
Journal Article |
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Year |
1992 |
Publication |
Biochimica et Biophysica Acta |
Abbreviated Journal |
Biochim Biophys Acta |
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Volume |
1121 |
Issue |
3 |
Pages |
269-278 |
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Keywords |
Animals; Crystallization; Horses; Kinetics; Methemoglobin/*chemistry; Solutions; Spectrum Analysis; Temperature; Thiocyanates/*chemistry |
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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. |
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Address |
Institut fur Biophysik, Ruhr-Universitat Bochum, Germany |
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Corporate Author |
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Thesis |
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Publisher |
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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 Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
0006-3002 |
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Notes |
PMID:1627604 |
Approved |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3800 |
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