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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
	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	0006-3002	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:1627604			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3800
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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
	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	0006-3002	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:2544230			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3803
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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.
	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
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	Author	Czerlinski, G.H.; Erickson, J.O.; Theorell, H.
	Title	Chemical relaxation studies on the horse liver alcohol dehydrogenase system			Type	Journal Article
	Year	1979	Publication	Physiological Chemistry and Physics	Abbreviated Journal	Physiol Chem Phys
	Volume	11	Issue	6	Pages	537-569
	Keywords	Alcohol Oxidoreductases/metabolism; Animals; Buffers; Electron Transport; Ethanol/metabolism; Horses; Hydrogen-Ion Concentration; Liver/enzymology; Mathematics; NAD/metabolism; Oscillometry; Osmolar Concentration; Temperature; Time Factors
	Abstract	Chemical relaxation studies on the system horse liver alcohol dehydrogenase, nicotinamide adenine dinucleotide, and ethanol were conducted observing fluorescence changes between 400 and 500 nm. Temperature-jump experiments were performed at pH 6.5, 7.0, 8.0, and 9.0; concentration-jump experiments at pH 9.0. The reciprocal of the slowest relaxation time was found to be linearly dependent upon the enzyme concentration for relatively low enzyme concentrations, as predicted earlier. Use of the wide pH-range necessitated expression of the four apparent dissociation constants of the catalytic reaction cycle in terms of pH-independent constants. The system was described in terms of only one (or two) catalysis-linked protons not associated with the electron transfer. Protonic steps in a buffered system are in rapid equilibrium, too fast to be measured with the equipment available. Assuming only two of the four bimolecular reaction steps in the four-step cycle are fast compared to the remaining two, six cases may be considered with six expressions for the reciprocal of the slowest relaxation time. Comparison with the experimental data revealed that the bimolecular reaction steps governing the slowest relaxation time change with pH. Above the effective time resolution of the temperature-lump instrument with fluorescence detection (0.1 msec) only one other relaxation time was detectable and only at pH 9. This relaxation time, found to be independent of the concentration of all reactants within experimental error (r = 10 +/- 5 msec), is most likely due to an interconversion among ternary complexes.
	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	0031-9325	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:44918			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3813
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	Author	Wilson, M.T.; Ranson, R.J.; Masiakowski, P.; Czarnecka, E.; Brunori, M.
	Title	A kinetic study of the pH-dependent properties of the ferric undecapeptide of cytochrome c (microperoxidase)			Type	Journal Article
	Year	1977	Publication	European Journal of Biochemistry / FEBS	Abbreviated Journal	Eur J Biochem
	Volume	77	Issue	1	Pages	193-199
	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
	Abstract	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.
	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	0014-2956	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:20304			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3814
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	Author	Kihara, H.; Nakatani, H.; Hiromi, K.; Hon-Nami, K.
	Title	Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide			Type	Journal Article
	Year	1977	Publication	Biochimica et Biophysica Acta	Abbreviated Journal	Biochim Biophys Acta
	Volume	460	Issue	3	Pages	480-489
	Keywords	Animals; Bacteria; Cytochrome c Group; Ferrocyanides; Horses; Kinetics; Mathematics; Oxidation-Reduction; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; Thermodynamics
	Abstract	The oxidation-reduction reaction of horse heart cytochrome c and cytochrome c (552, Thermus thermophilus), which is highly thermoresistant, was studied by temperature-jump method. Ferrohexacyanide was used as reductant. (Formula: see text.) Thermodynamic and activation parameters of the reaction obtained for both cytochromes were compared with each other. The results of this showed that (1) the redox potential of cytochrome c-552, + 0.19 V, is markedly less than that of horse heart cytochrome c. (2) deltaHox of cytochrome c-552 is considerably lower than that of horse heart cytochrome c. (3) deltaSox and deltaSred of cytochrome c-552 are more negative than those of horse heart cytochrome c. (4) kred of cytochrome c-552 is much lower than that of horse heart cytochrome c at room temperature.
	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	0006-3002	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:195599			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3815
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	Author	Bayley, P.; Martin, S.; Anson, M.
	Title	Temperature-jump circular dichroism: observation of chiroptical relaxation processes at millisecond time resolution			Type	Journal Article
	Year	1975	Publication	Biochemical and Biophysical Research Communications	Abbreviated Journal	Biochem Biophys Res Commun
	Volume	66	Issue	1	Pages	303-308
	Keywords	*Alcohol Oxidoreductases/metabolism; Animals; Circular Dichroism; Horses; Kinetics; Liver/enzymology; Mathematics; Protein Conformation; Temperature; Time Factors
	Abstract
	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	0006-291X	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:1172440			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3816
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	Author	Dunn, M.F.; Branlant, G.
	Title	Roles of zinc ion and reduced coenzyme in horse liver alcohol dehydrogenase catalysis. The mechanism of aldehyde activation			Type	Journal Article
	Year	1975	Publication	Biochemistry	Abbreviated Journal	Biochemistry
	Volume	14	Issue	14	Pages	3176-3182
	Keywords	Alcohol Oxidoreductases/metabolism; Aldehydes/pharmacology; Animals; Binding Sites; Enzyme Activation/drug effects; Horses; Hydrogen-Ion Concentration; Kinetics; Liver/enzymology; NAD/analogs & derivatives/pharmacology; Oxidation-Reduction; Protein Binding; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; Zinc/pharmacology
	Abstract	1,4,5,6-Tetrahydronicotinamide adenine dinucleotide (H2NADH) has been investigated as a reduced coenzyme analog in the reaction between trans-4-N,N-dimethylaminocinnamaldehyde (I) (lambdamax 398 nm, epsilonmax 3.15 X 10-4 M-minus 1 cm-minus 1) and the horse liver alcohol dehydrogenase-NADH complex. These equilibrium binding and temperature-jump kinetic studies establish the following. (i) Substitution of H2NADH for NADH limits reaction to the reversible formation of a new chromophoric species, lambdamax 468 nm, epsilonmax 5.8 x 10-4 M-minus 1 cm-minus 1. This chromophore is demonstrated to be structurally analogous to the transient intermediate formed during the reaction of I with the enzyme-NADH complex [Dunn, M. F., and Hutchison, J. S. (1973), Biochemistry 12, 4882]. (ii) The process of intermediate formation with the enzyme-NADH complex is independent of pH over the range 6.13-10.54. Although studies were limited to the pH range 5.98-8.72, a similar pH independence appears to hold for the H2NADH system. (iii) Within the ternary complex, I is bound within van der Waal's contact distance of the coenzyme nicotinamide ring. (iv) Formation of the transient intermediate does not involve covalent modification of coenzyme. Based on these findings, we conclude that zinc ion has a Lewis acid function in facilitating the chemical activation of the aldehyde carbonyl for reduction, and that reduced coenzyme plays a noncovalent effector role in this substrate activating step.
	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	0006-2960	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:238585			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3817
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	Author	Cho, K.C.; Chan, K.K.
	Title	Kinetics of cold-induced denaturation of metmyoglobin			Type	Journal Article
	Year	1984	Publication	Biochimica et Biophysica Acta (BBA) – Protein Structure and Molecular Enzymology	Abbreviated Journal
	Volume	786	Issue	1-2	Pages	103-108
	Keywords	Metmyoglobin denaturation; Temperature jump; Denaturation kinetics; Conformational transformation; (Horse heart)
	Abstract	Using a slow temperature-jump spectrophotometer, we have studied the kinetics of cold-induced denaturation of metmyoglobin between 0[degree sign]C and 20[degree sign]C at acidic pH. The time-scale of the transition is slow and is of the order of minutes. The results are consistent with the transition's involving a total of three states, native (N), transient intermediate (I) and denatured (D), which are converted from one to the other in that order.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	refbase @ user @			Serial	3978
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	Author	Kihara, H.
	Title	Comparison of the redox reactions of various types of cytochrome c with iron hexacyanides			Type	Journal Article
	Year	1981	Publication	Biochimica et Biophysica Acta (BBA) – Bioenergetics	Abbreviated Journal
	Volume	634	Issue		Pages	93-104
	Keywords	Cytochrome c; Redox reaction; Iron hexacyanide; Temperature jump; Electron transfer
	Abstract	The dynamic behavior of various types of cytochromes c in the redox reaction with iron hexacyanides was studied using a temperature-jump method in order to elucidate the molecular mechanism of the redox reaction of cytochromes with their oxidoreductants. Transmittance after the temperature jump changed through a single exponential decay for all cytochromes investigated. Under a constant concentration of anion, the redox reaction of various types of cytochrome c with iron hexacyanides was analyzed according to the scheme: Ki=kt/k-i (i=1,2,3) where C(III) and C(II) are ferric and ferrous cytochromes, respectively, Fe(III) and Fe(II) are ferri- and ferrocyanides, respectively, C(III) [middle dot] Fe(II) is the ferricytochrome-ferrocyanide complex and C(II) [middle dot] Fe(III) is the ferrocytochrome-ferricyanide complex. When step B is slower than the other two steps A and C, τ-1 can be represented approximately as where the bar over the variables denotes the equilibrium value. In a large excess of ferrocyanide against cytochrome, we can estimate k2, k-2, K1 and K3 independently. In the case of horse cytochrome c at 18[degree sign]C in 0.1 M phosphate buffer at pH 7 with 0.3 M KNO3, the estimated parameters are k2 = 100 +/- 50 s-1, k-2 = (3.5 +/- 1.0) [middle dot] 103 s-1, K1 = 15 +/- 7 M-1 and K3 = (8.5 +/- 1.5) [middle dot] 10-4 M. From the same experiments for seven cytochromes (cytochrome c from horse, tuna, Candida krusei, Saccharomyces oviformis, Rhodospirillum rubrum cytochrome c2, Spirulina platensis cytochrome c-554 and Thermus thermophilus cytochrome c-552), the following results can be deduced. (1) Each parameter defined in the scheme above (k2, k-2, K1, K3) diverged beyond the error range. Above all, k2 values of cytochromes c-554 and c-552 are as large as 1 [middle dot] 104 s-1 and much larger than those for the other cytochromes (to 50 approx. 700 S-1). (2) The variance of k2K1 and k-2/K3 are relatively less than the variances of individual parameters (k2, k-2, K1 and K3), which suggests that the values of k2K1 and k-2/K3 have been conserved during the course of evolution.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	refbase @ user @			Serial	3980
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