| Records |
| Author |
Miksovska, J.; Larsen, R.W. |
| Title |
Photothermal studies of pH induced unfolding of apomyoglobin |
Type |
Journal Article |
| Year |
2003 |
Publication  |
Journal of Protein Chemistry |
Abbreviated Journal |
J Protein Chem |
| Volume |
22 |
Issue |
4 |
Pages |
387-394 |
| Keywords |
Acoustics; Animals; Apoproteins/*chemistry/metabolism; Circular Dichroism; Horses; Myocardium/chemistry; Myoglobin/*chemistry/metabolism; Photolysis; Protein Conformation/radiation effects; Protein Denaturation/radiation effects; *Protein Folding; Temperature; Thermodynamics |
| Abstract |
Conformational dynamic and enthalpy changes associated with pH induced unfolding of apomyoglobin were studied using photoacoustic calorimetry and photothermal beam deflection methods. The transition between the native state and the I intermediate was induced by a nanosecond pH jump from o-nitrobenzaldehyde photolysis. Deconvolution of photoacoustic waves indicates two kinetic processes. The fast phase (T < 50 ns) is characterized by a volume expansion of 8.8 ml mol(-1). This process is followed by a volume contraction of about -22 ml mol(-1) (tau approximately 500 ns). Photothermal beam deflection measurements do not reveal any volume changes on the time scale between approximately 100 micros and 5 ms. We associate the volume contraction with structural changes occurring during the transition between the native state and the I intermediate. The lack of any processes on the ms time scale may indicate the absence of structural events involving larger conformational changes of apomyoglobin after the pH jump. |
| Address |
Department of Chemistry, University of South Florida, Tampa, Florida 33620, USA |
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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 |
0277-8033 |
ISBN |
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Conference |
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| Notes |
PMID:13678303 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3780 |
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| 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 |
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English |
Summary Language |
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| ISSN |
0002-7863 |
ISBN |
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Conference |
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| Notes |
PMID:11439052 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3788 |
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| Author |
Gilmanshin, R.; Callender, R.H.; Dyer, R.B. |
| Title |
The core of apomyoglobin E-form folds at the diffusion limit |
Type |
Journal Article |
| Year |
1998 |
Publication |
Nature Structural Biology |
Abbreviated Journal |
Nat Struct Biol |
| Volume |
5 |
Issue |
5 |
Pages |
363-365 |
| Keywords |
Animals; Apoproteins/*chemistry; Diffusion; Horses; Myoglobin/*chemistry; *Protein Folding; Spectroscopy, Fourier Transform Infrared; Temperature |
| 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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English |
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Series Issue |
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Edition |
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| ISSN |
1072-8368 |
ISBN |
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Conference |
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| Notes |
PMID:9586997 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3795 |
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| Author |
Uzawa, T.; Akiyama, S.; Kimura, T.; Takahashi, S.; Ishimori, K.; Morishima, I.; Fujisawa, T. |
| Title |
Collapse and search dynamics of apomyoglobin folding revealed by submillisecond observations of alpha-helical content and compactness |
Type |
Journal Article |
| Year |
2004 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
101 |
Issue |
5 |
Pages |
1171-1176 |
| Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Cytochromes c/chemistry; Horses; Myoglobin/*chemistry; *Protein Folding; *Protein Structure, Secondary; Scattering, Radiation |
| Abstract |
The characterization of protein folding dynamics in terms of secondary and tertiary structures is important in elucidating the features of intraprotein interactions that lead to specific folded structures. Apomyoglobin (apoMb), possessing seven helices termed A-E, G, and H in the native state, has a folding intermediate composed of the A, G, and H helices, whose formation in the submillisecond time domain has not been clearly characterized. In this study, we used a rapid-mixing device combined with circular dichroism and small-angle x-ray scattering to observe the submillisecond folding dynamics of apoMb in terms of helical content (f(H)) and radius of gyration (R(g)), respectively. The folding of apoMb from the acid-unfolded state at pH 2.2 was initiated by a pH jump to 6.0. A significant collapse, corresponding to approximately 50% of the overall change in R(g) from the unfolded to native conformation, was observed within 300 micros after the pH jump. The collapsed intermediate has a f(H) of 33% and a globular shape that involves >80% of all its atoms. Subsequently, a stepwise helix formation was detected, which was interpreted to be associated with a conformational search for the correct tertiary contacts. The characterized folding dynamics of apoMb indicates the importance of the initial collapse event, which is suggested to facilitate the subsequent conformational search and the helix formation leading to the native structure. |
| Address |
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan |
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English |
Summary Language |
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Edition |
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| ISSN |
0027-8424 |
ISBN |
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Conference |
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| Notes |
PMID:14711991 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3779 |
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| 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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English |
Summary Language |
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| ISSN |
0027-8424 |
ISBN |
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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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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 |
0887-3585 |
ISBN |
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Conference |
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| Notes |
PMID:8090705 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3799 |
| Permanent link to this record |
