Protein stability: urea-induced versus guanidine-induced unfolding of metmyoglobin.


We have studied the denaturation of metmyoglobin at pH 6.0 and 25 degrees C by urea and guanidine hydrochloride (GdnHCl) which are known to unfold the protein to the same extent. It has been observed that estimates of protein stability (delta G0N-U) from urea-induced and GdnHCl-induced denaturations do not agree with one another; the linear extrapolation method gave delta G0N-U values of 7.59 +/- 0.33 and 5.35 +/- 0.10 kcal mol-1 for urea and GdnHCl denaturations, respectively. Measurements of the effect of the addition of KCl in the concentration range 0.1-1.0 M to urea denaturation have suggested that this disagreement is not due to the nonionic and ionic characters of urea and GdnHCl, respectively. The functional dependence of the free energy change of unfolding (delta GN-U) on [denaturant], the molar concentration of the denaturant, has been investigated for understanding the cause(s) of the disagreement between the two estimates of delta G0N-U of metmyoglobin. For this purpose, we have studied the GdnHCl-induced denaturation of the protein in the presence of different urea concentrations at pH 6.0 and 25 degrees C and vice versa. These measurements yield delta GN-U values in the full concentration range [Ahmad et al. (1994) J. Biochem. 115, 322-327], and these results provide strong evidence that the delta GN-U dependence on [urea] is linear (linear free energy model of denaturation) and the relation between delta GN-U and [GdnHCl] is curved (binding model of denaturation). It has been observed that the extrapolated value of delta GN-U in urea using the linear free energy model becomes identical to the extrapolated value of delta GN-U in GdnHCl using the binding model. Study holds ProTherm entries: 4883, 4884 Extra Details: ionic characters; concentration range; linear free energy model;,binding model

Submission Details

ID: LnrgYM5R3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:27 p.m.

Version: 1

Publication Details
Gupta R;Yadav S;Ahmad F,Biochemistry (1996) Protein stability: urea-induced versus guanidine-induced unfolding of metmyoglobin. PMID:8794776
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Myoglobin P68083 MYG_EQUBU
100.0 Myoglobin P68082 MYG_HORSE
91.6 Myoglobin P02181 MYG_INIGE
92.2 Myoglobin P02169 MYG_LEPMU
90.9 Myoglobin P02166 MYG_PERPO
90.8 Myoglobin Q0KIY1 MYG_BALBO
90.8 Myoglobin Q0KIY2 MYG_BALED
90.8 Myoglobin P02177 MYG_ESCRO
90.9 Myoglobin P02189 MYG_PIG
90.1 Myoglobin P02178 MYG_MEGNO
90.3 Myoglobin P02183 MYG_MESCA
90.3 Myoglobin Q0KIY0 MYG_MESST
90.3 Myoglobin P02167 MYG_NYCCO
90.3 Myoglobin P02165 MYG_TUPGL
90.9 Myoglobin P11343 MYG_LUTLU
90.3 Myoglobin P02163 MYG_ROUAE