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Guanidinium chloride induction of partial unfolding in amide proton exchange in RNase A

Mayo, Stephen L. and Baldwin, Robert L. (1993) Guanidinium chloride induction of partial unfolding in amide proton exchange in RNase A. Science, 262 (5135). pp. 873-876. ISSN 0036-8075. doi:10.1126/science.8235609.

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Amide (NH) proton exchange rates were measured in 0.0 to 0.7 M guanidinium chloride (GdmCl) for 23 slowly exchanging peptide NH protons of ribonuclease A (RNase A) at pH* 5.5 (uncorrected pH measured in D_2O), 34 °C. The purpose was to find out whether GdmCl induces exchange through binding to exchange intermediates that are partly or wholly unfolded. It was predicted that, when the logarithm of the exchange rate is plotted as a function of the molarity of GdmCl, the slope should be a measure of the amount of buried surface area exposed to GdmCl in the exchange intermediate. The results indicate that these concentrations of GdmCl do induce exchange by means of a partial unfolding mechanism for all 23 protons; this implies that exchange reactions can be used to study the unfolding and stability of local regions. Of the 23 protons, nine also show a second mechanism of exchange at lower concentrations of GdmCl, a mechanism that is nearly independent of GdmCl concentration and is termed "limited structural fluctuation."

Item Type:Article
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URLURL TypeDescription DOIArticle
Mayo, Stephen L.0000-0002-9785-5018
Additional Information:© 1993 American Association for the Advancement of Science. Received 25 March 1993; accepted 20 September 1993. We thank D. Barrick, S. W. Englander, T. Kiefhaber, D. Laurents, and A. Robertson for help and discussion. Supported by NIH grant GM 19988.
Funding AgencyGrant Number
NIHGM 19988
Subject Keywords:Magnetic Resonance Spectroscopy; Thermodynamics; Protein Denaturation; Guanidine; Mathematics; Protein Folding; Hydrogen-Ion Concentration; Hydrogen; Ribonuclease: Pancreatic; Protons; Guanidines; Temperature
Issue or Number:5135
Record Number:CaltechAUTHORS:20110620-160428244
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24093
Deposited By: Marie Ary
Deposited On:28 Sep 2011 21:29
Last Modified:01 Jun 2023 23:30

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