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Author |
Dunn, M.F.; Branlant, G. |
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Title |
Roles of zinc ion and reduced coenzyme in horse liver alcohol dehydrogenase catalysis. The mechanism of aldehyde activation |
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Journal Article |
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Year |
1975 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
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Volume |
14 |
Issue |
14 |
Pages |
3176-3182 |
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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 |
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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. |
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0006-2960 |
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PMID:238585 |
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Equine Behaviour @ team @ |
Serial |
3817 |
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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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Equine Behaviour @ team @ |
Serial |
3807 |
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Author |
Fazio, E.; Medica, P.; Cravana, C.; Giacoppo, E.; Ferlazzo, A. |
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Title |
Effect of Short-Distance Road Transport on Thyroid Function, Rectal Temperature, Body Weight and Heart Rate of Stallions |
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Conference Article |
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Year |
2008 |
Publication |
IESM 2008 |
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horses, iodothyronines, rectal temperature, body weight, heart rate, transport |
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Aim of study was to investigate the effects of transport stress on thyroid response, body weight, rectal temperature and heart rate changes in one hundred twenty-six healthy stallions in basal conditions, before and after short road transport. One hundred twenty-six Thoroughbreds and crossbreds stallions with previous travelling experience, aged 4 to 15 yr, were transported by road in a commercial trailer for a period of 3 h (distance <300 km). Blood samples and physiological parameters were collected at 0800 (basal I) and at 1100 (basal II), in each horse“s box, one week before the loading and transport in basal conditions, and one week later, at 0800 immediately before loading (pre-transport), and after 3 h period of transport and unloading, on their arrival at the breeding stations (post-transport), in each new horse”s box, within 30 min. Increases in circulating T3, T4 and fT4 levels (P < 0.01), but not for fT3 levels, were observed after transport, as compared to before loading values, irrespective of different breed. Lower T4 and fT4 levels were observed in basal II (P < 0.01) than basal I and before loading values (pre-transport). After transport Thoroughbreds showed higher fT3 (P < 0.05) and fT4 (P < 0.01) levels than crossbred stallions. No significant differences for T3 and T4 changes were observed. A significant increase in rectal temperature (P < 0.01) and heart rate (P < 0.05) was observed after transport, as compared to before loading values (pre-transport). No differences between basal I, basal II and before loading values (pre-transport) for physiological parameters were observed.
The highest T3, T4 and fT4 levels recorded after short transport seem to suggest a preferential release from the thyroid gland. The results indicate that short road transport stress contributes significantly to thyroid hormone changes, according to different breed, and to the increase in rectal temperature and heart rate. No differences related to different age were observed. |
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Department of Morphology, Biochemistry, Physiology and Animal Production – Unit of Veterinary Physiology, Faculty of Veterinary Medicine, University of Messina, Polo Universitario Annunziata, 98168 Messina, Italy |
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Cravana, C. |
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IESM 2008 |
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Poster IESM 2008 |
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yes |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4494 |
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Author |
Gilmanshin, R.; Callender, R.H.; Dyer, R.B. |
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Title |
The core of apomyoglobin E-form folds at the diffusion limit |
Type |
Journal Article |
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Year |
1998 |
Publication |
Nature Structural Biology |
Abbreviated Journal |
Nat Struct Biol |
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Volume |
5 |
Issue |
5 |
Pages |
363-365 |
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Keywords |
Animals; Apoproteins/*chemistry; Diffusion; Horses; Myoglobin/*chemistry; *Protein Folding; Spectroscopy, Fourier Transform Infrared; Temperature |
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Abstract |
The E-form of apomyoglobin has been characterized using infrared and fluorescence spectroscopies, revealing a compact core with native like contacts, most probably consisting of 15-20 residues of the A, G and H helices of apomyoglobin. Fast temperature-jump, time-resolved infrared measurements reveal that the core is formed within 96 micros at 46 degrees C, close to the diffusion limit for loop formation. Remarkably, the folding pathway of the E-form is such that the formation of a limited number of native-like contacts is not rate limiting, or that the contacts form on the same time scale expected for diffusion controlled loop formation. |
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1072-8368 |
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PMID:9586997 |
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Equine Behaviour @ team @ |
Serial |
3795 |
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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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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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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3783 |
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Author |
Hagen, S.J.; Eaton, W.A. |
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Title |
Two-state expansion and collapse of a polypeptide |
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Journal Article |
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Year |
2000 |
Publication |
Journal of Molecular Biology |
Abbreviated Journal |
J Mol Biol |
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Volume |
301 |
Issue |
4 |
Pages |
1019-1027 |
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Keywords |
Animals; Computer Simulation; Cytochrome c Group/*chemistry/*metabolism; Horses; Kinetics; Lasers; Models, Chemical; Peptides/*chemistry/*metabolism; Protein Conformation; Protein Denaturation; *Protein Folding; Spectrometry, Fluorescence; Temperature; Thermodynamics |
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The initial phase of folding for many proteins is presumed to be the collapse of the polypeptide chain from expanded to compact, but still denatured, conformations. Theory and simulations suggest that this collapse may be a two-state transition, characterized by barrier-crossing kinetics, while the collapse of homopolymers is continuous and multi-phasic. We have used a laser temperature-jump with fluorescence spectroscopy to measure the complete time-course of the collapse of denatured cytochrome c with nanosecond time resolution. We find the process to be exponential in time and thermally activated, with an apparent activation energy approximately 9 k(B)T (after correction for solvent viscosity). These results indicate that polypeptide collapse is kinetically a two-state transition. Because of the observed free energy barrier, the time scale of polypeptide collapse is dramatically slower than is predicted by Langevin models for homopolymer collapse. |
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Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Building 5, Bethesda, MD, 20892-0520, USA |
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0022-2836 |
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PMID:10966803 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3790 |
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Author |
Hrdy, S.B. |
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Title |
Male-male competition and infanticide among the langurs (Presbytis entellus) of Abu, Rajasthan |
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Journal Article |
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Year |
1974 |
Publication |
Folia Primatologica; International Journal of Primatology |
Abbreviated Journal |
Folia Primatol (Basel) |
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22 |
Issue |
1 |
Pages |
19-58 |
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Keywords |
Aggression; Animals; Animals, Newborn; Coitus; *Competitive Behavior; Estrus; Feeding Behavior; Female; *Haplorhini; Homing Behavior; Humans; India; Infanticide; Leadership; Male; Maternal Behavior; Population Density; Pregnancy; Rain; Seasons; Sex Factors; Sexual Behavior, Animal; Social Behavior; Temperature; Vocalization, Animal |
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0015-5713 |
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PMID:4215710 |
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no |
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2051 |
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Author |
Hughes, K.L.; Sulaiman, I. |
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Title |
The ecology of Rhodococcus equi and physicochemical influences on growth |
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Journal Article |
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Year |
1987 |
Publication |
Veterinary Microbiology |
Abbreviated Journal |
Vet Microbiol |
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14 |
Issue |
3 |
Pages |
241-250 |
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Keywords |
Animals; Feces/microbiology; Horses; Hydrogen-Ion Concentration; Rhodococcus/*growth & development; *Soil Microbiology; Temperature |
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Abstract |
Growth of Rhodococcus equi was studied in vitro. Optimal growth occurred under aerobic conditions between pH 7.0 and 8.5, at 30 degrees C. R. equi survived better in a neutral soil (pH 7.3) than it did in two acid soils (pH less than 5.5). It grew substantially better in soils enriched with faeces than in soils alone. Simple organic acids in horse dung, especially acetate and propionate, appear to be important in supporting growth of R. equi in the environment. The ecology of R. equi can be best explained by an environmental cycle allowing its proliferation in dung, influenced by management, grazing behaviour and prevailing climatic conditions. Preventive measures should be aimed at reducing or avoiding focal areas of faecal contamination in the environment. |
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School of Veterinary Science, University of Melbourne, Parkville, Vic., Australia |
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0378-1135 |
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PMID:3672866 |
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no |
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Equine Behaviour @ team @ |
Serial |
2678 |
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Author |
Kihara, H. |
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Title |
Comparison of the redox reactions of various types of cytochrome c with iron hexacyanides |
Type |
Journal Article |
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Year |
1981 |
Publication |
Biochimica et Biophysica Acta (BBA) – Bioenergetics |
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Volume |
634 |
Issue |
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Pages |
93-104 |
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Keywords |
Cytochrome c; Redox reaction; Iron hexacyanide; Temperature jump; Electron transfer |
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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. |
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refbase @ user @ |
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3980 |
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Author |
Kihara, H.; Nakatani, H.; Hiromi, K.; Hon-Nami, K. |
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Title |
Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide |
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Journal Article |
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Year |
1977 |
Publication |
Biochimica et Biophysica Acta |
Abbreviated Journal |
Biochim Biophys Acta |
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Volume |
460 |
Issue |
3 |
Pages |
480-489 |
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Keywords |
Animals; Bacteria; *Cytochrome c Group; *Ferrocyanides; Horses; Kinetics; Mathematics; Oxidation-Reduction; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; Thermodynamics |
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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. |
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0006-3002 |
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PMID:195599 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3815 |
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