Denatured states of ribonuclease A have compact dimensions and residual secondary structure. |
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Authors: | T R Sosnick J Trewhella |
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Institution: | Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545. |
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Abstract: | Using small-angle X-ray scattering and Fourier transform infrared spectroscopy, we have determined that the thermally denatured state of native ribonuclease A is on average a compact structure having residual secondary structure. Under strongly reducing conditions, the protein further unfolds into a looser structure with larger dimensions but still retains a comparable amount of secondary structure. The dimensions of the thermally and chemically denatured states of the reduced protein are different but both are more compact than is predicted for a random coil of the same length. These results demonstrate that thermal denaturation in ribonuclease A is not a simple two-state transition from a native to a completely disordered random coil state. |
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