Denatured protein

From Wikipedia, the free encyclopedia

The introduction to this article provides insufficient context for those unfamiliar with the subject matter.
Please help improve the introduction to meet Wikipedia's layout standards. You can discuss the issue on the talk page.

A denatured protein is one which has been denatured and thus has lost its functional conformation. Random coil scaling of the radius of gyration of unfolded proteins with the size has been reported.^[1] But, it need not be a totally random conformation as evidenced by the above scaling. Significant degree of structure in the unfolded state has also been experimentally observed.^[2] These seemingly contradictory observations point to rather protein-specific and denaturant-specific effects which cannot be generalized. Interestingly, a model which takes both these into account has been proposed by Sosnick and co-workers^[3]

Once denatured, a protein loses most, if not all of its biological activity. A protein can be denatured through various means including exposure to extremes of heat, pH, salt concentration, denaturing agents like urea/guanidine chloride and use of detergents. Chaperonins are able to denature proteins transiently in order to force them to refold into their correct native conformation. During digestion, proteins are denatured by stomach acid allowing them to be degraded by proteolytic enzymes to their amino acid components.

When a protein is denatured, the secondary and tertiary structures are altered but the peptide bonds between the amino acids are left intact. Since the structure of the protein determines its function, the protein can no longer perform its function once it has been denatured. This is in contrast to intrinsically unstructured proteins, that are unfolded in their native state, but still functionally active.

[edit] References

^ Kohn JE, Millett IS, Jacob J, Zagrovic B, Dillon TM, Cingel N, Dothager RS, Seifert S, Thiyagarajan P, Sosnick TR, Hasan MZ, Pande VS, Ruczinski I, Doniach S, Plaxco KW. (2004). Random-coil behavior and the dimensions of chemically unfolded proteins. Proc. Natl. Acad. Sci. USA 101:12491-12496 PMID 15314214
^ Shortle D & Ackerman MS. (2001). Persistence of native-like topology in a denatured protein in 8 M urea. Science 293:487-489 PMID 11463915
^ Jha A, Colubri A, Freed KF & Sosnick TR. (2005). Statistical coil model of the unfolded state:Resolving the reconciliation problem. Proc. Natl. Acad. Sci. USA 102:13099-13104 PMID 16131545