Abstract
The high resolution dielectric spectra of semidilute solutions of apomyoglobin in native (N, pH = 5), acid-induced molten globule (A, pH = 4), and unfolded (U(A), pH = 3) states have been measured in the range from 0.2 to 20 GHz. Based on a two-component mixture theory, we obtained the following hydration numbers per protein molecule: 590 +/- 65 for N, 630 +/- 73 for A, and 1110 +/- 67 for U(A). There was no clear difference between N and A states in contrast to the 25% reduction of helix content and the 50% reduction of heat capacity change upon unfolding. This suggests that the association of hydrophobic moieties might follow the disruption of secondary structures from N to A states. The measured hydration number of U(A) was close to that of the accessible water number (1340) of a protein molecule calculated for a fully extended structure, indicating that the structure of U(A) is extended but somewhat more compact than that of a fully extended state.
Full Text
The Full Text of this article is available as a PDF (164.1 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Goto Y., Fink A. L. Phase diagram for acidic conformational states of apomyoglobin. J Mol Biol. 1990 Aug 20;214(4):803–805. doi: 10.1016/0022-2836(90)90334-I. [DOI] [PubMed] [Google Scholar]
- Griko Y. V., Privalov P. L. Thermodynamic puzzle of apomyoglobin unfolding. J Mol Biol. 1994 Jan 28;235(4):1318–1325. doi: 10.1006/jmbi.1994.1085. [DOI] [PubMed] [Google Scholar]
- Griko Y. V., Privalov P. L., Venyaminov S. Y., Kutyshenko V. P. Thermodynamic study of the apomyoglobin structure. J Mol Biol. 1988 Jul 5;202(1):127–138. doi: 10.1016/0022-2836(88)90525-6. [DOI] [PubMed] [Google Scholar]
- Hapner K. D., Bradshaw R. A., Hartzell C. R., Gurd F. R. Comparison of myoglobins from harbor seal, porpoise, and sperm whale. I. Preparation and characterization. J Biol Chem. 1968 Feb 25;243(4):683–689. [PubMed] [Google Scholar]
- Kataoka M., Nishii I., Fujisawa T., Ueki T., Tokunaga F., Goto Y. Structural characterization of the molten globule and native states of apomyoglobin by solution X-ray scattering. J Mol Biol. 1995 May 26;249(1):215–228. doi: 10.1006/jmbi.1995.0290. [DOI] [PubMed] [Google Scholar]
- Nishii I., Kataoka M., Goto Y. Thermodynamic stability of the molten globule states of apomyoglobin. J Mol Biol. 1995 Jul 7;250(2):223–238. doi: 10.1006/jmbi.1995.0373. [DOI] [PubMed] [Google Scholar]
- Nishii I., Kataoka M., Tokunaga F., Goto Y. Cold denaturation of the molten globule states of apomyoglobin and a profile for protein folding. Biochemistry. 1994 Apr 26;33(16):4903–4909. doi: 10.1021/bi00182a019. [DOI] [PubMed] [Google Scholar]
- Pennock B. E., Schwan H. P. Further observations on the electrical properties of hemoglobin-bound water. J Phys Chem. 1969 Aug;73(8):2600–2610. doi: 10.1021/j100842a024. [DOI] [PubMed] [Google Scholar]
- Suzuki M., Shigematsu J., Fukunishi Y., Harada Y., Yanagida T., Kodama T. Coupling of protein surface hydrophobicity change to ATP hydrolysis by myosin motor domain. Biophys J. 1997 Jan;72(1):18–23. doi: 10.1016/S0006-3495(97)78643-0. [DOI] [PMC free article] [PubMed] [Google Scholar]