Evidence for involvement of proline cis-trans isomerization in the slow unfolding reaction of RNase A.
- 1 February 1980
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 77 (2), 795-798
- https://doi.org/10.1073/pnas.77.2.795
Abstract
The 3 exposed tyrosines of RNase A were converted to nitrotyrosines by reaction with tetranitromethane, and the changes in the ionization properties of these nitrotyrosines were used to follow the kinetics of unfolding of the nitrated protein. The nitrotyrosines not only are sensitive to the overall disruption of the protein structure, which occurs in a faster reaction, but also serve as reporter groups for the slower reaction which takes place in the unfolded state. This slower reaction corresponds to the formation of the slow-refolding species of the unfolded protein. The kinetic properties of the slower reaction, guanidine-dependence of the rate and activation enthalpy, are similar to those of the proline cis-trans isomerization in a model peptide determined in the same conditions. Proline cis-trans isomerization is indeed the rate-limiting factor for the formation of the slow-refolding species. Because the influence of proline cis-trans isomerization on the properties of the nitrotyrosines in the unfolded protein is probably due to a local effect, most of the optical changes observed during this slow unfolding reaction may arise from the effect of the cis-trans isomerization of the Asn113-Pro114 bond on the properties of nitrotyrosine 115.This publication has 16 references indexed in Scilit:
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