Noncooperative temperature melting of a globular protein without specific tertiary structure: Acid form of bovine carbonic anhydrase B
✍ Scribed by E. V. Brazhnikov; Yu. N. Chirgadze; D. A. Dolgikh; O. B. Ptitsyn
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1985
- Tongue
- English
- Weight
- 493 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Heat denaturation of native globular proteins is a cooperative process usually connected with the melting of the main part of their regular secondary structure. In this paper, a noncooperative temperature-induced melting of the regular secondary structure in the carbonic anhydrase B at pH 2.6 in heavy water is observed by ir spectroscopy. The molecules of carbonic anhydrase B in an acid medium, unlike the native ones, do not have a specific tertiary structure. Nevertheless, the p-structure content is about the same in both of these states. A temperature-induced noncooperative melting process takes place from 10 to 67°C with a decrease of the antiparallel p-form content by about one third. The remaining part of the p-form melts with a more intensive heat absorption, with a maximum at 87°C. The whole melting process is practically reversible. We assume that the observed noncooperative process displays a general property of a new type of structural state of the globular protein-the "molten globule state.