Publication Date:
1993-11-05
Description:
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 D2O), 34 degrees 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."〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mayo, S L -- Baldwin, R L -- GM 19988/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1993 Nov 5;262(5135):873-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Stanford University School of Medicine 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8235609" target="_blank"〉PubMed〈/a〉
Keywords:
Guanidine
;
Guanidines/*pharmacology
;
Hydrogen/chemistry
;
Hydrogen-Ion Concentration
;
Magnetic Resonance Spectroscopy
;
Mathematics
;
Protein Denaturation
;
*Protein Folding
;
Protons
;
Ribonuclease, Pancreatic/*chemistry
;
Temperature
;
Thermodynamics
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
