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Hossain M, Huda N, Bhuyan AK. A three-state mechanism for trifluoroethanol denaturation of an intrinsically disordered protein (IDP). J Biochem 2023; 174:519-531. [PMID: 37709541 DOI: 10.1093/jb/mvad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 09/05/2023] [Accepted: 09/13/2023] [Indexed: 09/16/2023] Open
Abstract
Relating the amino acid composition and sequence to chain folding and binding preferences of intrinsically disordered proteins (IDPs) has emerged as a huge challenge. While globular proteins have respective 3D structures that are unique to their individual functions, IDPs violate this structure-function paradigm because rather than having a well-defined structure an ensemble of rapidly interconverting disordered structures characterize an IDP. This work measures 2,2,2-trifluoroethanol (TFE)-induced equilibrium transitions of an IDP called AtPP16-1 (Arabidopsis thaliana phloem protein type 16-1) by using fluorescence, circular dichroism, infrared and nuclear magnetic resonance (NMR) methods at pH 4, 298 K. Low TFE reversibly removes the tertiary structure to produce an ensemble of obligate intermediate ($\mathrm{I}$) retaining the native-state ($\mathrm{N}$) secondary structure. The intermediate $\mathrm{I}$ is preceded by a non-obligate tryptophan-specific intermediate ${\mathrm{I}}_{\mathrm{w}}$ whose population is detectable for AtPP16-1 specifically. Accumulation of such non-obligate intermediates is discriminated according to the sequence composition of the protein. In all cases, however, a tertiary structure-unfolded general obligate intermediate $\mathrm{I}$ is indispensable. The $\mathrm{I}$ ensemble has higher helical propensity conducive to the acquisition of an exceedingly large level of α-helices by a reversible denaturation transition of $\mathrm{I}$ to the denatured state $\mathrm{D}$ as the TFE level is increased. Strikingly, it is the same $\mathrm{N}\rightleftharpoons \mathrm{I}\rightleftharpoons \mathrm{D}$ scheme typifying the TFE transitions of globular proteins. The high-energy state $\mathrm{I}$ characterized by increased helical propensity is called a universal intermediate encountered in both genera of globular and disordered proteins. Neither $\mathrm{I}$ nor $\mathrm{D}$ strictly show molten globule (MG)-like properties, dismissing the belief that TFE promotes MGs.
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Affiliation(s)
- Mujahid Hossain
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Noorul Huda
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Abani K Bhuyan
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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2
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Hossain M, Huda N, Bhuyan AK. A surprisingly simple three-state generic process for reversible protein denaturation by trifluoroethanol. Biophys Chem 2022; 291:106895. [PMID: 36182744 DOI: 10.1016/j.bpc.2022.106895] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/12/2022] [Accepted: 09/14/2022] [Indexed: 12/30/2022]
Abstract
Despite the rich knowledge of the influence of 2,2,2-trifluoroethanol (TFE) on the structure and conformation of peptides and proteins, the mode(s) of TFE-protein interactions and the mechanism by which TFE reversibly denatures a globular protein remain elusive. This study systematically examines TFE-induced equilibrium transition curves for six paradigmatic globular proteins by using basic fluorescence and circular dichroism measurements under neutral pH conditions. The results are remarkably simple. Low TFE invariably unfolds the tertiary structure of all proteins to produce the obligate intermediate (I) which retains nearly all of native-state secondary structure, but enables the formation of extra α-helices as the level of TFE is raised higher. Inspection of the transitions at once reveals that the tertiary structure unfolding is always a distinct process, necessitating the inclusion of at least one obligate intermediate in the TFE-induced protein denaturation. It appears that the intermediate in the minimal unfolding mechanism N⇌I⇌D somehow acquires higher α-helical propensity to generate α-helices in excess of that in the native state to produce the denatured state (D), also called the TFE state. The low TFE-populated intermediate I may be called a universal intermediate by virtue of its α-helical propensity. Contrary to many earlier suggestions, this study dismisses molten globule (MG)-like attribute of I or D.
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Affiliation(s)
- Mujahid Hossain
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Noorul Huda
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Abani K Bhuyan
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
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3
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Yamaguchi T, Akao K, Koutsioubas A, Frielinghaus H, Kohzuma T. Open-Bundle Structure as the Unfolding Intermediate of Cytochrome c' Revealed by Small Angle Neutron Scattering. Biomolecules 2022; 12:95. [PMID: 35053243 PMCID: PMC8774185 DOI: 10.3390/biom12010095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/31/2021] [Accepted: 01/04/2022] [Indexed: 11/27/2022] Open
Abstract
The dynamic structure changes, including the unfolding, dimerization, and transition from the compact to the open-bundle unfolding intermediate structure of Cyt c', were detected by a small-angle neutron scattering experiment (SANS). The structure of Cyt c' was changed into an unstructured random coil at pD = 1.7 (Rg = 25 Å for the Cyt c' monomer). The four-α-helix bundle structure of Cyt c' at neutral pH was transitioned to an open-bundle structure (at pD ~13), which is given by a numerical partial scattering function analysis as a joint-clubs model consisting of four clubs (α-helices) connected by short loops. The compactly folded structure of Cyt c' (radius of gyration, Rg = 18 Å for the Cyt c' dimer) at neutral or mildly alkaline pD transited to a remarkably larger open-bundle structure at pD ~13 (Rg = 25 Å for the Cyt c' monomer). The open-bundle structure was also supported by ab initio modeling.
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Affiliation(s)
- Takahide Yamaguchi
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Ibaraki, Japan; (T.Y.); (K.A.)
- Frontier Research Center of Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai 319-1106, Ibaraki, Japan
| | - Kouhei Akao
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Ibaraki, Japan; (T.Y.); (K.A.)
| | - Alexandros Koutsioubas
- Jülich Centre for Neutron Science JCNS-4 at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, D-85747 Garching, Germany; (A.K.); (H.F.)
| | - Henrich Frielinghaus
- Jülich Centre for Neutron Science JCNS-4 at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, D-85747 Garching, Germany; (A.K.); (H.F.)
| | - Takamitsu Kohzuma
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Ibaraki, Japan; (T.Y.); (K.A.)
- Frontier Research Center of Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai 319-1106, Ibaraki, Japan
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4
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Jain R, Sharma D, Kumar R, Kumar R. Structural, kinetic and thermodynamic characterizations of SDS-induced molten globule state of a highly negatively charged cytochrome c. J Biochem 2019; 165:125-137. [PMID: 30371870 DOI: 10.1093/jb/mvy087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 10/26/2018] [Indexed: 11/14/2022] Open
Abstract
This study presents the structural, kinetic and thermodynamic characterizations of previously unknown submicellar concentrations of SDS-induced molten globule (MGSDS) state of a highly negatively charged base-denatured ferricytochrome c (UB-state) at pH ∼12.8 (±0.2). The far-UV CD, near-UV CD, ANS-fluorescence data of UB-state in the presence of different concentrations of SDS indicate that the submicellar concentrations of SDS (≤0.4 mM) transform the UB-state to MGSDS-state. The MGSDS-state has native-like α-helical secondary structure but lacks tertiary structure. The free energy change (ΔG°D) for UB→ MGSDS transition determined by far-UV CD (∼2.7 kcal mol-1) is slightly higher than those determined by fluorescence (∼2.0 kcal mol-1) at 25°C. At very low SDS and NaCl concentrations, the MGSDS-state undergoes cold denaturation. As SDS concentration is increased, the thermal denaturation temperature increases and the cold denaturation temperature decrease. Kinetic experiments involving the measurement of the CO-association rate to the base-denatured ferrocytochrome c at pH ≈12.8 (±0.2), 25°C indicate that the submicellar concentrations of SDS restrict the internal dynamics of base-denatured protein.
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Affiliation(s)
- Rishu Jain
- School of Chemistry and Biochemistry, Thapar University, Patiala, India.,Department of Chemistry, Gujranwala Guru Nanak Khalsa College, Ghumar Mandi, Civil Lines, Ludhiana, India
| | - Deepak Sharma
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Rakesh Kumar
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Rajesh Kumar
- School of Chemistry and Biochemistry, Thapar University, Patiala, India.,School of Basic and Applied Sciences, Department of Chemical Sciences, Central University of Punjab, Bathinda, India
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Nakamura S, Saotome T, Nakazawa A, Fukuda M, Kuroda Y, Kidokoro SI. Thermodynamics of the Thermal Denaturation of Acid Molten Globule State of Cytochrome c Indicate a Reversible High-Temperature Oligomerization Process. Biochemistry 2017; 56:2372-2378. [DOI: 10.1021/acs.biochem.6b01225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shigeyoshi Nakamura
- Department
of General Education, National Institute of Technology, Ube College, 2-14-1 Tokiwadai, Ube 755-8555, Japan
- Department
of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
| | - Tomonori Saotome
- Department
of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-15 Nakamachi, Koganei 184-8588, Japan
| | - Akiko Nakazawa
- Department
of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
| | - Masao Fukuda
- Department
of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
| | - Yutaka Kuroda
- Department
of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-15 Nakamachi, Koganei 184-8588, Japan
| | - Shun-ichi Kidokoro
- Department
of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
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6
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Zhang N, Liu FF, Dong XY, Sun Y. Synergistic inhibition of acid-induced protein denaturation by trehalose and NaCl: Thermodynamic and kinetic studies. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2014.08.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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Crowded milieu prevents fibrillation of hen egg white lysozyme with retention of enzymatic activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:8-16. [DOI: 10.1016/j.jphotobiol.2014.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 11/18/2022]
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8
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Ghosh S, Pandey NK, Banerjee P, Chaudhury K, Nagy NV, Dasgupta S. Copper(II) directs formation of toxic amorphous aggregates resulting in inhibition of hen egg white lysozyme fibrillation under alkaline salt-mediated conditions. J Biomol Struct Dyn 2014; 33:991-1007. [PMID: 24806136 DOI: 10.1080/07391102.2014.921864] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hen egg white lysozyme (HEWL) adopts a molten globule-like state at high pH (~12.75) and is found to form amyloid fibrils at alkaline pH. Here, we report that Cu(II) inhibits self-association of HEWL at pH 12.75 both at 37 and 65 °C. A significant reduction in Thioflavin T fluorescence intensity, attenuation in β-sheet content and reduction in hydrophobic exposure were observed with increasing Cu(II) stoichiometry. Electron paramagnetic resonance spectroscopy suggests a 4N type of coordination pattern around Cu(II) during fibrillation. Cu(II) is also capable of altering the cytotoxicity of the proteinaceous aggregates. Fibrillar species of diverse morphology were found in the absence of Cu(II) with the generation of amorphous aggregates in the presence of Cu(II), which are more toxic compared to the fibrils alone.
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Affiliation(s)
- Sudeshna Ghosh
- a Department of Chemistry , Indian Institute of Technology , Kharagpur 721302 , India
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9
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Sashi P, Yasin UM, Balasubramanian H, Sree MU, Ramakrishna D, Bhuyan AK. Preferential water exclusion in protein unfolding. J Phys Chem B 2014; 118:717-23. [PMID: 24354363 DOI: 10.1021/jp4111103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Association of water with protein plays a central role in the latter's folding, structure acquisition, ligand binding, catalytic reactivity, oligomerization, and crystallization. Because these phenomena are also influenced by the net charge content on the protein, the present study examines the association of water with cytochrome c held at different pH values so as to allow its side chains to ionize to variable extents. Equilibrium unfolding of differently charged cytochrome c molecules in water-methanol binary mixtures, where the alcohol acts as the cosolvent denaturant, was used to quantify the preferential exclusion of water during the unfolding transition. The extent of exclusion was found to be related to the net-charge-dependent molecular expansion of the protein in an alcohol-free aqueous medium. The degree of water exclusion was also found to be linearly related to the observed rate of protein unfolding, where the net charge contents of the initial and final states are the same. The results suggest that side-chain ionization, molecular expansion due to charge repulsion, and hence the loss of tertiary contacts lead to additional water-protein association. Protein unfolding rates appear to be linearly correlated with the effective number of water molecules excluded across the end states of unfolding equilibria.
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Affiliation(s)
- Pulikallu Sashi
- School of Chemistry University of Hyderabad , Hyderabad 500 046, India
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10
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Tripathy J, Mueller JJ, Shepherd NC, Beck WF. Dynamic solvation and coupling of the hydration shell of Zn(II)-substituted cytochrome c in the presence of guanidinium ions. J Phys Chem B 2013; 117:14589-98. [PMID: 24237324 DOI: 10.1021/jp404554t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The fluorescence Stokes shift (FSS) response of Zn(II)-substituted cytochrome c (ZnCytc) is transformed from a monotonic red-shifting response in water to a bidirectional response with much slower time constants in the presence of low concentrations of guanidinium (Gdm(+)) ions. The FSS response in water observed over the 100 ps to 10 ns range has two exponential components with time constants of 135 ps and 1.6 ns that account for a total shift of 30 cm(-1), about one-half of the solvation reorganization energy. In contrast, in the presence of only 0.25 M Gdm(+), the FSS response initially shifts 21 cm(-1) to the blue with a 820 ps time constant and then shifts 60 cm(-1) back to the red with a 3.5 ns time constant. The effect of Gdm(+) on the FSS response effectively saturates at 1.0 M, well below the 1.75 M midpoint of the two-state unfolding transition. These results establish that the FSS response in ZnCytc includes a significant contribution from the surrounding hydration shell, which assumes a perturbed hydrogen-bonding network owing to the binding of Gdm(+) ions to the protein surface. The blue-shifting part of the FSS response arises from a light-induced conformational change that expands the protein- and solvent-derived cavity around the excited-state Zn(II) porphyrin. This non-polar part of the solvation response is enhanced in the presence of Gdm(+) because the protein/solvent surroundings of the Zn(II) porphyrin are effectively more flexible than in water. The enhanced flexibility in the presence of Gdm(+) increases the amplitudes and accordingly lengthens the correlation time scales for the protein and hydration-shell fluctuations that contribute to the FSS response.
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Affiliation(s)
- Jagnyaseni Tripathy
- Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
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11
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Zhang N, Liu FF, Dong XY, Sun Y. Counteraction of trehalose on urea-induced protein unfolding: Thermodynamic and kinetic studies. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2013.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Yasin UM, Sashi P, Bhuyan AK. Expansion and Internal Friction in Unfolded Protein Chain. J Phys Chem B 2013; 117:12059-64. [DOI: 10.1021/jp408718c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- U. Mahammad Yasin
- School of Chemistry, University of Hyderabad, Hyderabad 500
046, India
| | - Pulikallu Sashi
- School of Chemistry, University of Hyderabad, Hyderabad 500
046, India
| | - Abani K. Bhuyan
- School of Chemistry, University of Hyderabad, Hyderabad 500
046, India
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13
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Equilibrium and kinetic studies of the counteraction of trehalose on acid-induced protein unfolding. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2012.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Jain R, Kaur S, Kumar R. Guanidine hydrochloride-induced alkali molten globule model of horse ferrocytochrome c. J Biochem 2012; 153:161-77. [DOI: 10.1093/jb/mvs134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Sashi P, Yasin UM, Bhuyan AK. Unfolding action of alcohols on a highly negatively charged state of cytochrome C. Biochemistry 2012; 51:3273-83. [PMID: 22439732 DOI: 10.1021/bi201716r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is well-known that hydrophobic effect play a major role in alcohol-protein interactions leading to structure unfolding. Studies with extremely alkaline cytochrome c (U(B) state, pH 13) in the presence of the first four alkyl alcohols suggests that the hydrophobic effect persistently overrides even though the protein carries a net charge of -17 under these conditions. Equilibrium unfolding of the U(B) state is accompanied by an unusual expansion of the chain involving an intermediate, I(alc), from which water is preferentially excluded, the extent of water exclusion being greater with the hydrocarbon content of the alcohol. The mobility and environmental averaging of side chains in the I(alc) state are generally constrained relative to those in the U(B) state. A few nuclear magnetic resonance-detected tertiary interactions are also found in the I(alc) state. The fact that the I(alc) state populates at low concentrations of methanol and ethanol and the fact that the extent of chain expansion in this state approaches that of the U(B) state indicate a definite influence of electrostatic repulsion severed by the low dielectric of the water/alcohol mixture. Interestingly, the U(B) ⇌ I(alc) segment of the U(B) ⇌ I(alc) ⇌ U equilibrium, where U is the unfolded state, accounts for roughly 85% of the total number of water molecules preferentially excluded in unfolding. Stopped-flow refolding results report on a submillisecond hydrophobic collapse during which almost the entire buried surface area associated with the U(B) state is recovered, suggesting the overwhelming influence of hydrophobic interaction over electrostatic repulsions.
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Affiliation(s)
- Pulikallu Sashi
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
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Nakamura S, Kidokoro SI. Volumetric Properties of the Molten Globule State of Cytochrome c in the Thermal Three-State Transition Evaluated by Pressure Perturbation Calorimetry. J Phys Chem B 2012; 116:1927-32. [DOI: 10.1021/jp209686e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
| | - Shun-ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
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17
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Nakamura S, Seki Y, Katoh E, Kidokoro SI. Thermodynamic and structural properties of the acid molten globule state of horse cytochrome C. Biochemistry 2011; 50:3116-26. [PMID: 21388230 DOI: 10.1021/bi101806b] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To understand the stabilization, folding, and functional mechanisms of proteins, it is very important to understand the structural and thermodynamic properties of the molten globule state. In this study, the global structure of the acid molten globule state, which we call MG1, of horse cytochrome c at low pH and high salt concentrations was evaluated by solution X-ray scattering (SXS), dynamic light scattering, and circular dichroism measurements. MG1 was globular and slightly (3%) larger than the native state, N. Calorimetric methods, such as differential scanning calorimetry and isothermal acid-titration calorimetry, were used to evaluate the thermodynamic parameters in the transitions of N to MG1 and MG1 to denatured state D of horse cytochrome c. The heat capacity change, ΔC(p), in the N-to-MG1 transition was determined to be 2.56 kJ K(-1) mol(-1), indicating the increase in the level of hydration in the MG1 state. Moreover, the intermediate state on the thermal N-to-D transition of horse cytochrome c at pH 4 under low-salt conditions showed the same structural and thermodynamic properties of the MG1 state in both SXS and calorimetric measurements. The Gibbs free energy changes (ΔG) for the N-to-MG1 and N-to-D transitions at 15 °C were 10.9 and 42.2 kJ mol(-1), respectively.
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Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
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18
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Khan MKA, Rahaman H, Ahmad F. Conformation and thermodynamic stability of pre-molten and molten globule states of mammalian cytochromes-c. Metallomics 2011; 3:327-38. [DOI: 10.1039/c0mt00078g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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