Water and urea interactions with the native and unfolded forms of a beta-barrel protein.


A fundamental understanding of protein stability and the mechanism of denaturant action must ultimately rest on detailed knowledge about the structure, solvation, and energetics of the denatured state. Here, we use (17)O and (2)H magnetic relaxation dispersion (MRD) to study urea-induced denaturation of intestinal fatty acid-binding protein (I-FABP). MRD is among the few methods that can provide molecular-level information about protein solvation in native as well as denatured states, and it is used here to simultaneously monitor the interactions of urea and water with the unfolding protein. Whereas CD shows an apparently two-state transition, MRD reveals a more complex process involving at least two intermediates. At least one water molecule binds persistently (with residence time >10 nsec) to the protein even in 7.5 M urea, where the large internal binding cavity is disrupted and CD indicates a fully denatured protein. This may be the water molecule buried near the small hydrophobic folding core at the D-E turn in the native protein. The MRD data also provide insights about transient (residence time <1 nsec) interactions of urea and water with the native and denatured protein. In the denatured state, both water and urea rotation is much more retarded than for a fully solvated polypeptide. The MRD results support a picture of the denatured state where solvent penetrates relatively compact clusters of polypeptide segments. Study holds ProTherm entries: 17312, 17313 Extra Details: Protein denaturation; fatty acid-binding protein; urea; solvent exchange; magnetic relaxation dispersion

Submission Details

ID: zeBciEfR

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:49 p.m.

Version: 1

Publication Details
Modig K;Kurian E;Prendergast FG;Halle B,Protein Sci. (2003) Water and urea interactions with the native and unfolded forms of a beta-barrel protein. PMID:14627737
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 Fatty acid-binding protein, brain P55051 FABP7_RAT
97.0 Fatty acid-binding protein, brain P51880 FABP7_MOUSE
100.0 Fatty acid-binding protein, intestinal P02693 FABPI_RAT
92.4 Fatty acid-binding protein, intestinal P55050 FABPI_MOUSE