Tryptophan Fluorescence Reveals the Presence of Long-Range Interactions in the Denatured State of Ribonuclease Sa
| Autor: | C. Nick Pace, Gerald R. Grimsley, J. Martin Scholtz, Roy W. Alston, Gregory D. Reinhart, Mauricio Lasagna |
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| Jazyk: | angličtina |
| Předmět: |
Time Factors
RNase P Molecular Sequence Data Iodide Molecular Conformation Biophysics Fluorescence 03 medical and health sciences chemistry.chemical_compound Ribonucleases Side chain Urea Amino Acid Sequence Disulfides Ribonuclease 030304 developmental biology chemistry.chemical_classification Acrylamide Acrylamides 0303 health sciences biology 030302 biochemistry & molecular biology Tryptophan Proteins Iodides Spectrometry Fluorescence chemistry Biochemistry Ribonuclease Sa biology.protein Protein folding Peptides |
| Zdroj: | Biophysical Journal. (6):2288-2296 |
| ISSN: | 0006-3495 |
| DOI: | 10.1529/biophysj.107.116954 |
| Popis: | Characterizing the denatured state ensemble is crucial to understanding protein stability and the mechanism of protein folding. The aim of this research was to see if fluorescence could be used to gain new information on the denatured state ensemble. Ribonuclease Sa (RNase Sa) contains no Trp residues. We made five variants of RNase Sa by adding Trp residues at locations where they are found in other members of the microbial ribonuclease family. To better understand the protein denatured state, we also studied the fluorescence properties of the following peptides: N-acetyl-Trp-amide (NATA), N-acetyl-Ala-Trp-Ala-amide (AWA), N-acetyl-Ala-Ala-Trp-Ala-Ala-amide (AAWAA), and the five pentapeptides with the same sequence as the Trp substitution sites in RNase Sa. The major conclusions are: 1), the wavelength of maximum fluorescence intensity, lambda(max), does not differ significantly for the peptides and the denatured proteins; 2), the fluorescence intensity at lambda(max), I(F), differs significantly for the five Trp containing variants of RNase Sa; 3), the I(F) differences for the denatured proteins are mirrored in the peptides, showing that the short-range effects giving rise to the I(F) differences in the peptides are also present in the proteins; 4) the I(F) values for the denatured proteins are more than 30% greater than for the peptides, showing the presence of long-range effects in the proteins; 5), fluorescence quenching of Trp by acrylamide and iodide is more than 50% greater in the peptides than in the denatured proteins, showing that long-range effects limit the accessibility of the quenchers to the Trp side chains in the proteins; and 6), these results show that nonlocal effects in the denatured states of proteins influence Trp fluorescence and accessibility significantly. |
| Databáze: | OpenAIRE |
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