|
Records |
Links |
|
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. |
|
|
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 |
0021-924X |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
PMID:6270075 |
Approved |
no |
|
|
Call Number |
Equine Behaviour @ team @ |
Serial |
3808 |
|
Permanent link to this record |
|
|
|
|
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 |
|
Permanent link to this record |
|
|
|
|
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 |
|
Permanent link to this record |
|
|
|
|
Author |
Polverini, E.; Cugini, G.; Annoni, F.; Abbruzzetti, S.; Viappiani, C.; Gensch, T. |
|
|
Title |
Molten globule formation in apomyoglobin monitored by the fluorescent probe Nile Red |
Type |
Journal Article |
|
Year |
2006 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
|
|
Volume |
45 |
Issue |
16 |
Pages |
5111-5121 |
|
|
Keywords |
Animals; Apoproteins/*chemistry/*metabolism; Binding Sites; Computer Simulation; Fluorescent Dyes/analysis; Horses; Hydrogen-Ion Concentration; Models, Molecular; Myoglobin/*chemistry/*metabolism; Oxazines/*analysis/chemistry; Protein Binding; Protein Folding; Protein Structure, Tertiary |
|
|
Abstract |
The interaction of nile red (NR) with apomyoglobin (ApoMb) in the native (pH 7) and molten globule (pH 4) states was investigated using experimental and computational methods. NR binds to hydrophobic locations in ApoMb with higher affinity (K(d) = 25 +/- 5 microM) in the native state than in the molten globule state (K(d) = 52 +/- 5 microM). In the molten globule state, NR is located in a more hydrophobic environment. The dye does not bind to the holoprotein, suggesting that the binding site is located at the heme pocket. In addition to monitoring steady-state properties, the fluorescence emission of NR is capable of tracking submillisecond, time-resolved structural rearrangements of the protein, induced by a nanosecond pH jump. Molecular dynamics simulations were run on ApoMb at neutral pH and at pH 4. The structure obtained for the molten globule state is consistent with the experimentally available structural data. The docking of NR with the crystal structure shows that the ligand binds into the binding pocket of the heme group, with an orientation bringing the planar ring system of NR to overlap with the position of two of the heme porphyrin rings in Mb. The docking of NR with the ApoMb structure at pH 4 shows that the dye binds to the heme pocket with a slightly less favorable binding energy, in keeping with the experimental K(d) value. Under these conditions, NR is positioned in a different orientation, reaching a more hydrophobic environment in agreement with the spectroscopic data. |
|
|
Address |
Dipartimento di Fisica, Universita degli Studi di Parma, Viale G. P. Usberti 7/A, 43100 Parma, Italy |
|
|
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:16618100 |
Approved |
no |
|
|
Call Number |
Equine Behaviour @ team @ |
Serial |
3763 |
|
Permanent link to this record |
|
|
|
|
Author |
Gulotta, M.; Gilmanshin, R.; Buscher, T.C.; Callender, R.H.; Dyer, R.B. |
|
|
Title |
Core formation in apomyoglobin: probing the upper reaches of the folding energy landscape |
Type |
Journal Article |
|
Year |
2001 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
|
|
Volume |
40 |
Issue |
17 |
Pages |
5137-5143 |
|
|
Keywords |
Animals; Apoproteins/*chemistry; Computer Simulation; Horses; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; *Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Spectrometry, Fluorescence/instrumentation/methods; Thermodynamics; Tryptophan/chemistry |
|
|
Abstract |
An acid-destabilized form of apomyoglobin, the so-called E state, consists of a set of heterogeneous structures that are all characterized by a stable hydrophobic core composed of 30-40 residues at the intersection of the A, G, and H helices of the protein, with little other secondary structure and no other tertiary structure. Relaxation kinetics studies were carried out to characterize the dynamics of core melting and formation in this protein. The unfolding and/or refolding response is induced by a laser-induced temperature jump between the folded and unfolded forms of E, and structural changes are monitored using the infrared amide I' absorbance at 1648-1651 cm(-1) that reports on the formation of solvent-protected, native-like helix in the core and by fluorescence emission changes from apomyoglobin's Trp14, a measure of burial of the indole group of this residue. The fluorescence kinetics data are monoexponential with a relaxation time of 14 micros. However, infrared kinetics data are best fit to a biexponential function with relaxation times of 14 and 59 micros. These relaxation times are very fast, close to the limits placed on folding reactions by diffusion. The 14 micros relaxation time is weakly temperature dependent and thus represents a pathway that is energetically downhill. The appearance of this relaxation time in both the fluorescence and infrared measurements indicates that this folding event proceeds by a concomitant formation of compact secondary and tertiary structures. The 59 micros relaxation time is much more strongly temperature dependent and has no fluorescence counterpart, indicating an activated process with a large energy barrier wherein nonspecific hydrophobic interactions between helix A and the G and H helices cause some helix burial but Trp14 remains solvent exposed. These results are best fit by a multiple-pathway kinetic model when U collapses to form the various folded core structures of E. Thus, the results suggest very robust dynamics for core formation involving multiple folding pathways and provide significant insight into the primary processes of protein folding. |
|
|
Address |
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA |
|
|
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:11318635 |
Approved |
no |
|
|
Call Number |
Equine Behaviour @ team @ |
Serial |
3789 |
|
Permanent link to this record |
|
|
|
|
Author |
Haruta, N.; Kitagawa, T. |
|
|
Title |
Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: characterization of kinetic folding intermediates of apomyoglobin |
Type |
Journal Article |
|
Year |
2002 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
|
|
Volume |
41 |
Issue |
21 |
Pages |
6595-6604 |
|
|
Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Holoenzymes/chemistry; Horses; Hydrochloric Acid/chemistry; Hydrogen-Ion Concentration; Imidazoles/chemistry; Kinetics; Models, Molecular; Myoglobin/*chemistry; Peptide Fragments/chemistry; *Protein Folding; Protein Structure, Secondary; Spectrum Analysis, Raman/*methods; Tryptophan/*chemistry; Ultraviolet Rays; Whales |
|
|
Abstract |
The 244-nm excited transient UV resonance Raman spectra are observed for the refolding intermediates of horse apomyoglobin (h-apoMb) with a newly constructed mixed flow cell system, and the results are interpreted on the basis of the spectra observed for the equilibrium acid unfolding of the same protein. The dead time of mixing, which was determined with the appearance of UV Raman bands of imidazolium upon mixing of imidazole with acid, was 150 micros under the flow rate that was adopted. The pH-jump experiments of h-apoMb from pH 2.2 to 5.6 conducted with this device demonstrated the presence of three folding intermediates. On the basis of the analysis of W3 and W7 bands of Trp7 and Trp14, the first intermediate, formed before 250 micros, involved incorporation of Trp14 into the alpha-helix from a random coil. The frequency shift of the W3 band of Trp14 observed for this process was reproduced with a model peptide of the A helix when it forms the alpha-helix. In the second intermediate, formed around 1 ms after the start of refolding, the surroundings of both Trp7 and Trp14 were significantly hydrophobic, suggesting the formation of the hydrophobic core. In the third intermediate appearing around 3 ms, the hydrophobicity was relaxed to the same level as that of the pH 4 equilibrium intermediate, which was investigated in detail with the stationary state technique. The change from the third intermediate to the native state needs more time than 40 ms, while the appearance of the native spectrum after the mixing of the same solutions was confirmed separately. |
|
|
Address |
School of Mathematical and Physical Sciences, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan |
|
|
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:12022863 |
Approved |
no |
|
|
Call Number |
Equine Behaviour @ team @ |
Serial |
3785 |
|
Permanent link to this record |
|
|
|
|
Author |
Abbruzzetti, S.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. |
|
|
Title |
Kinetics of histidine deligation from the heme in GuHCl-unfolded Fe(III) cytochrome C studied by a laser-induced pH-jump technique |
Type |
Journal Article |
|
Year |
2001 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
|
|
Volume |
123 |
Issue |
27 |
Pages |
6649-6653 |
|
|
Keywords |
Animals; *Bacterial Proteins; Cytochrome c Group/*chemistry; Guanidine/*chemistry; Heme/*chemistry; Histidine/*chemistry; Horses; Hydrogen-Ion Concentration; Kinetics; *Lasers; Ligands; Protein Folding |
|
|
Abstract |
We have developed an instrumental setup that uses transient absorption to monitor protein folding/unfolding processes following a laser-induced, ultrafast release of protons from o-nitrobenzaldehyde. The resulting increase in [H(+)], which can be more than 100 microM, is complete within a few nanoseconds. The increase in [H(+)] lowers the pH of the solution from neutrality to approximately 4 at the highest laser pulse energy used. Protein structural rearrangements can be followed by transient absorption, with kinetic monitoring over a broad time range (approximately 10 ns to 500 ms). Using this pH-jump/transient absorption technique, we have examined the dissociation kinetics of non-native axial heme ligands (either histidine His26 or His33) in GuHCl-unfolded Fe(III) cytochrome c (cyt c). Deligation of the non-native ligands following the acidic pH-jump occurs as a biexponential process with different pre-exponential factors. The pre-exponential factors markedly depend on the extent of the pH-jump, as expected from differences in the pK(a) values of His26 and His33. The two lifetimes were found to depend on temperature but were not functions of either the magnitude of the pH-jump or the pre-pulse pH of the solution. The activation energies of the deligation processes support the suggestion that GuHCl-unfolded cyt c structures with non-native histidine axial ligands represent kinetic traps in unfolding. |
|
|
Address |
Dipartimento di Fisica, Universita di Parma, Istituto Nazionale per la Fisica della Materia, 43100 Parma, Italy |
|
|
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 |
0002-7863 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
PMID:11439052 |
Approved |
no |
|
|
Call Number |
Equine Behaviour @ team @ |
Serial |
3788 |
|
Permanent link to this record |