Cited by 85Protein Structure and DynamicsHemoglobin structure and functionAdvanced NMR Techniques and Applications

High Pressure NMR Reveals that Apomyoglobin is an Equilibrium Mixture from the Native to the Unfolded

Kitahara, Ryo, Yamada, Hiroaki, Akasaka, Kazuyuki, Wright, Peter E.·2002·Journal of Molecular Biology

Abstract

Pressure-induced reversible conformational changes of sperm whale apomyoglobin have been studied between 30 bar and 3000 bar on individual residue basis by utilizing 1H/15N hetero nuclear single-quantum coherence two-dimensional NMR spectroscopy at pH 6.0 and 35 degrees C. Apomyoglobin showed a series of pressure-dependent NMR spectra as a function of pressure, assignable to the native (N), intermediates (I), molten globule (MG) and unfolded (U) conformers. At 30 bar, the native fold (N) shows disorder only in the F helix. Between 500 bar and 1200 bar, a series of locally disordered conformers I are produced, in which local disorder occurs in the C helix, the CD loop, the G helix and part of the H helix. At 2000 bar, most cross-peaks exhibit severe line-broadening, suggesting the formation of a molten globule, but at 3000 bar all the cross-peaks reappear, showing that the molten globule turns into a well-hydrated, mobile unfolded conformation U. Since all the spectral changes were reversible with pressure, apomyoglobin is considered to exist as an equilibrium mixture of the N, I, MG and U conformers at all pressures. MG is situated at 2.4+/-(0.1) kcal/mol above N at 1 bar and the unfolding transition from the combined N-I state to MG is accompanied by a loss of partial molar volume by 75+/-(3) ml/mol. On the basis of these observations, we postulate a theorem that the partial molar volume of a protein decreases in parallel with the loss of its conformational order.

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Crossref · 10.1016/s0022-2836(02)00449-7

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Authors
Kitahara, R., Yamada, H., Akasaka, K., & Wright, P. E.
Affiliations
  • Kobe University (JP)
  • RIKEN (JP)
  • Scripps Research Institute (US)
Corresponding author
Akasaka, Kazuyuki
Venue
Journal of Molecular Biology
Publisher
Elsevier BV
Published
2002-07
Volume
320
Issue
2
Pages
311-319
ISSN
0022-2836 (ISSN-L)
OpenAlex
W1964038158
Cited by
85
References
51
Citations by year
2026: 2 · 2025: 2 · 2024: 2 · 2023: 5 · 2022: 1 · 2019: 4 · 2018: 2 · 2017: 5 · 2016: 3 · 2015: 6 · 2014: 4 · 2013: 5 · 2012: 7
FWCI
1.97
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Molecular Biology (publishedVersion)
  • PubMed (publishedVersion)
Funders
Ministry of Education, Culture, Sports, Science and Technology
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Structure and Dynamics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Hemoglobin structure and function
  • Physical Sciences › Chemistry › Spectroscopy › Advanced NMR Techniques and Applications
Keywords
apomyoglobin, sperm whale, high pressure, pressure-induced unfolding, molten globule, folding intermediates, conformational equilibrium, partial molar volume, protein hydration, line broadening, reversible conformational change
MeSH terms
Apoproteins, Escherichia coli, Models, Molecular, Myoglobin, Magnetic Resonance Spectroscopy, Protein Conformation, Thermodynamics, Protein Folding

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