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

Modig, Kristofer LU ; Kurian, E; Prendergast, F G and Halle, Bertil LU (2003) In Protein Science 12(12). p.2768-2781
Abstract
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 17O and 2H 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... (More)
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 17O and 2H 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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Protein Science
volume
12
issue
12
pages
2768 - 2781
publisher
The Protein Society
external identifiers
  • wos:000186764600011
  • pmid:14627737
  • scopus:0345708214
ISSN
1469-896X
DOI
10.1110/ps.03262603
language
English
LU publication?
yes
id
59acb7ca-28ae-4363-9570-dbb53cc35db5 (old id 128079)
date added to LUP
2007-06-29 14:00:07
date last changed
2018-01-07 06:22:16
@article{59acb7ca-28ae-4363-9570-dbb53cc35db5,
  abstract     = {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 17O and 2H 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 &gt;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 &lt;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.},
  author       = {Modig, Kristofer and Kurian, E and Prendergast, F G and Halle, Bertil},
  issn         = {1469-896X},
  language     = {eng},
  number       = {12},
  pages        = {2768--2781},
  publisher    = {The Protein Society},
  series       = {Protein Science},
  title        = {Water and urea interactions with the native and unfolded forms of a beta-barrel protein.},
  url          = {http://dx.doi.org/10.1110/ps.03262603},
  volume       = {12},
  year         = {2003},
}