Solvent-exposed tryptophans probe the dynamics at protein surfaces

Lakshmikanth, G. S. ; Krishnamoorthy, Guruswamy (1999) Solvent-exposed tryptophans probe the dynamics at protein surfaces Biophysical Journal, 77 (2). pp. 1100-1106. ISSN 0006-3495

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The dynamics of single tryptophan (W) side chain of protease subtilisin Carlsberg (SC) and myelin basic protein (MBP) were used for probing the surface of these proteins. The W side chains are exposed to the solvent, as shown by the extent of quenching of their fluorescence by KI. Time-resolved fluorescence anisotropy measurements showed that the rotational motion of W is completely unhindered in the case of SC and partially hindered in the case of MBP. The rotational correlation time (Φ) associated with the fast local motion of W did not scale linearly with the bulk solvent viscosity (η) in glycerol-water mixtures. In contrast, Φ values of either W side chains in the denatured proteins or the free W scaled almost linearly with η, as expected by the Stokes-Einstein relationship. These results were interpreted as indicating specific partitioning of water at the surface of the proteins in glycerol-water mixtures.

Item Type:Article
Source:Copyright of this article belongs to Biophysical Society.
ID Code:17951
Deposited On:17 Nov 2010 13:27
Last Modified:17 May 2016 02:40

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