Abstract
Using measurements of quasi-elastic light scattering spectra, we have investigated diffusional fluctuations of RNase. The diffusion coefficient for individual protein molecules, together with the corresponding calculated effective molecular radius Reff, were determined. Between room temperature and the point of irreversible denaturation at 63.5°C, Reff increased from 20-250 A. This is comparable to the plateau in Reff of 300 A reached after about 200 min following chemical denaturation in 10 M urea. The measurements indicated the presence of a large size component even in the freshly prepared and chromatographically purified solutions. From the diffusion constants deduced for this large component we obtained effective sizes from 1000-5000 A. Concentration and temperature dependent measurements exclude the possibility that these large particles are impurities and indicate that they are the result of aggregations of RNase molecules.
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Selected References
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- Brandts J. F., Hunt L. The thermodynamics of protein denaturation. 3. The denaturation of ribonuclease in water and in aqueous urea and aqueous ethanol mixtures. J Am Chem Soc. 1967 Sep 13;89(19):4826–4838. doi: 10.1021/ja00995a002. [DOI] [PubMed] [Google Scholar]
- CRESTFIELD A. M., STEIN W. H., MOORE S. On the aggregation of bovine pancreatic ribonuclease. Arch Biochem Biophys. 1962 Sep;Suppl 1:217–222. [PubMed] [Google Scholar]
- Dubin S. B., Lunacek J. H., Benedek G. B. Observation of the spectrum of light scattered by solutions of biological macromolecules. Proc Natl Acad Sci U S A. 1967 May;57(5):1164–1171. doi: 10.1073/pnas.57.5.1164. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HARRINGTON W. F., SCHELLMAN J. A. Evidence for the instability of hydrogen-bonded peptide structures in water, based on studies of ribonuclease and oxidized ribonuclease. C R Trav Lab Carlsberg Chim. 1956;30(3):21–43. [PubMed] [Google Scholar]