Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-8675
Kozinski, M; Garrett-Roe, S; Hamm, P (2008). 2D-IR spectroscopy of the sulfhydryl band of cysteines in the hydrophobic core of proteins. Journal of Physical Chemistry. B, 112(25):7645-7650.
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We investigate the sulfhydryl band of cysteines as a new chromophore for two-dimensional IR (2D-IR) studies of the structure and dynamics of proteins. Cysteines can be put at almost any position in a protein by standard methods of site-directed mutagenesis and, hence, have the potential to be an extremely versatile local probe. Although being a very weak absorber in aqueous environment, the sulfhydryl group gets strongly polarized when situated in an alpha-helix inside the hydrophobic core of a protein because of a strong hydrogen bond to the backbone carbonyl group. The extinction coefficient (epsilon = 150 M-1 cm(-1)) then is sufficiently high to perform detailed 2D-IR studies even at low millimolar concentrations. Using porcine (carbonmonoxy)hemoglobin as an example, which contains two such cysteines in its wild-type form, we demonstrate that spectral diffusion deduced from the 2D-IR line shapes reports on the overall-breathing of the corresponding (x-helix. The vibrational lifetime of the sulfhydryl group (T-1 approximate to 6 ps) is considerably longer than that of the much more commonly used amide I mode (approximate to 1.0 ps), thereby significantly extending the time window in which spectral diffusion processes can be observed. The experiments are accompanied by molecular dynamics simulations revealing a good overall agreement.
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|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||07 Faculty of Science > Department of Chemistry|
|Dewey Decimal Classification:||540 Chemistry|
|Date:||26 June 2008|
|Deposited On:||15 Jan 2009 11:40|
|Last Modified:||05 Apr 2016 12:44|
|Publisher:||American Chemical Society|
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