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Author Hoang, L.; Maity, H.; Krishna, M.M.G.; Lin, Y.; Englander, S.W. openurl 
  Title Folding units govern the cytochrome c alkaline transition Type Journal Article
  Year 2003 Publication Journal of Molecular Biology Abbreviated Journal J Mol Biol  
  Volume 331 Issue 1 Pages 37-43  
  Keywords Animals; Cytochrome c Group/*chemistry; Horses; Hydrogen/chemistry; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; *Protein Folding; Protein Structure, Tertiary; Spectrum Analysis; Titrimetry  
  Abstract The alkaline transition of cytochrome c is a model for protein structural switching in which the normal heme ligand is replaced by another group. Stopped flow data following a jump to high pH detect two slow kinetic phases, suggesting two rate-limiting structure changes. Results described here indicate that these events are controlled by the same structural unfolding reactions that account for the first two steps in the reversible unfolding pathway of cytochrome c. These and other results show that the cooperative folding-unfolding behavior of protein foldons can account for a variety of functional activities in addition to determining folding pathways.  
  Address Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA. lhoang@mail.upenn.edu  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN 0022-2836 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:12875834 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3781  
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Author Haruta, N.; Kitagawa, T. openurl 
  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 (up)  
  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  
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Author Abbruzzetti, S.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. openurl 
  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 (up)  
  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  
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Author Gulotta, M.; Gilmanshin, R.; Buscher, T.C.; Callender, R.H.; Dyer, R.B. openurl 
  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 (up)  
  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  
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Author Abbruzzetti, S.; Crema, E.; Masino, L.; Vecli, A.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. openurl 
  Title Fast events in protein folding: structural volume changes accompanying the early events in the N-->I transition of apomyoglobin induced by ultrafast pH jump Type Journal Article
  Year 2000 Publication Biophysical Journal Abbreviated Journal Biophys J  
  Volume 78 Issue 1 Pages 405-415  
  Keywords Animals; Apoproteins/*chemistry; Horses; *Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Protein Structure, Secondary; Spectrometry, Fluorescence  
  Abstract Ultrafast, laser-induced pH jump with time-resolved photoacoustic detection has been used to investigate the early protonation steps leading to the formation of the compact acid intermediate (I) of apomyoglobin (ApoMb). When ApoMb is in its native state (N) at pH 7.0, rapid acidification induced by a laser pulse leads to two parallel protonation processes. One reaction can be attributed to the binding of protons to the imidazole rings of His24 and His119. Reaction with imidazole leads to an unusually large contraction of -82 +/- 3 ml/mol, an enthalpy change of 8 +/- 1 kcal/mol, and an apparent bimolecular rate constant of (0.77 +/- 0.03) x 10(10) M(-1) s(-1). Our experiments evidence a rate-limiting step for this process at high ApoMb concentrations, characterized by a value of (0. 60 +/- 0.07) x 10(6) s(-1). The second protonation reaction at pH 7. 0 can be attributed to neutralization of carboxylate groups and is accompanied by an apparent expansion of 3.4 +/- 0.2 ml/mol, occurring with an apparent bimolecular rate constant of (1.25 +/- 0.02) x 10(11) M(-1) s(-1), and a reaction enthalpy of about 2 kcal/mol. The activation energy for the processes associated with the protonation of His24 and His119 is 16.2 +/- 0.9 kcal/mol, whereas that for the neutralization of carboxylates is 9.2 +/- 0.9 kcal/mol. At pH 4.5 ApoMb is in a partially unfolded state (I) and rapid acidification experiments evidence only the process assigned to carboxylate protonation. The unusually large contraction and the high energetic barrier observed at pH 7.0 for the protonation of the His residues suggests that the formation of the compact acid intermediate involves a rate-limiting step after protonation.  
  Address Dipartimento di Fisica, Universita di Parma, 43100 Parma, Italia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN 0006-3495 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:10620304 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3792  
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Author Galloux, P.; Barrey, E. openurl 
  Title Components of the total kinetic moment in jumping horses Type Journal Article
  Year 1997 Publication Equine Veterinary Journal. Supplement Abbreviated Journal Equine Vet J Suppl  
  Volume Issue 23 Pages 41-44  
  Keywords Algorithms; Animals; Exertion/*physiology; Female; Gravitation; Horses/*physiology; Kinetics; Locomotion/*physiology; Male; Models, Biological; Movement/*physiology; Video Recording  
  Abstract Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 x 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take-off, jump and landing phases. It was found that the trunk, hindlimbs and head-neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 +/- 5 degrees/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 +/- 125 kg x m2/s).  
  Address Ecole Nationale d'Equitation, Terrefort, Saumur, France  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9354287 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3797  
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Author Ballew, R.M.; Sabelko, J.; Gruebele, M. openurl 
  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  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN 0027-8424 ISBN Medium  
  Area Expedition Conference  
  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. doi  openurl
  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  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN 0887-3585 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:8090705 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3799  
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Author Steinhoff, H.J.; Schrader, J.; Schlitter, J. openurl 
  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 (up)  
  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 Gonzalez-Fernandez, J.M.; Atta, S.E. openurl 
  Title Facilitated transport of oxygen in the presence of membranes in the diffusion path Type Journal Article
  Year 1982 Publication Biophysical Journal Abbreviated Journal Biophys J  
  Volume 38 Issue 2 Pages 133-141  
  Keywords Animals; Biological Transport, Active; Cell Membrane/*metabolism; Diffusion; Dogs; Horses; Humans; Kinetics; Mathematics; *Models, Biological; Muscles/*metabolism; Oxygen/*metabolism  
  Abstract Most of the experimental observations on facilitated transport have been done with millipore filters, and all the theoretical studies have assumed homogeneous spatial properties. In striated muscle there exist membranes that may impede the diffusion of the carrier myoglobin. In this paper a theoretical study is undertaken to analyze the transport in the presence of membranes in the diffusion path. For the numerical computations physiologically relevant values of the parameters were chosen. The numerical results indicate that the presence of membranes tends to decrease the facilitation. For the nonlinear chemical kinetics of the reaction of oxygen with the carrier, this decrement also depends on the location of the membranes. At the higher oxygen concentration side of each membrane the flow of combined oxygen is transferred to the flow of dissolved oxygen. The reverse process occurs at the lower concentration side. Jump discontinuities of the concentration of the oxygen-carrier compound at each membrane are associated with these transfers. The decrement of facilitation is due to the cumulative effect of these jump discontinuities.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title (up)  
  Series Volume Series Issue Edition  
  ISSN 0006-3495 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:7093418 Approved no  
  Call Number Equine Behaviour @ team @ Serial 3806  
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