Continuous dissolution of structure during the unfolding of a small protein

Jha, Santosh Kumar ; Dhar, Deepak ; Krishnamoorthy, Guruswamy ; Udgaonkar, Jayant B. (2009) Continuous dissolution of structure during the unfolding of a small protein Proceedings of the National Academy of Sciences of the United States of America, 106 (27). pp. 11113-11118. ISSN 0027-8424

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The unfolding kinetics of many small proteins appears to be first order, when measured by ensemble-averaging probes such as fluorescence and circular dichroism. For one such protein, monellin, it is shown here that hidden behind this deceptive simplicity is a complexity that becomes evident with the use of experimental probes that are able to discriminate between different conformations in an ensemble of structures. In this study, the unfolding of monellin has been probed by measurement of the changes in the distributions of 4 different intramolecular distances, using a multisite, time-resolved fluorescence resonance energy transfer methodology. During the course of unfolding, the protein molecules are seen to undergo slow and continuous, diffusive swelling. The swelling process can be modeled as the slow diffusive swelling of a Rouse-like chain with some additional noncovalent, intramolecular interactions. Here, we show that specific structure is lost during the swelling process gradually, and not in an all-or-none manner, during unfolding.

Item Type:Article
Source:Copyright of this article belongs to National Academy of Sciences, USA.
Keywords:Diffusive Swelling; Distance Distribution; Gradual Unfolding; Rouse Model; Time-resolved FRET
ID Code:9279
Deposited On:29 Oct 2010 11:58
Last Modified:16 May 2016 19:06

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