Int. J. Mol. Sci. 2014, 15(6), 10018-10033; doi:10.3390/ijms150610018
Article

A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy

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Received: 16 February 2014; in revised form: 26 May 2014 / Accepted: 27 May 2014 / Published: 4 June 2014
(This article belongs to the collection Proteins and Protein-Ligand Interactions)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Second derivative and Fourier self-deconvolution (FSD) are two commonly used techniques to resolve the overlapped component peaks from the often featureless amide I band in Fourier transform infrared (FTIR) curve-fitting approach for protein secondary structural analysis. Yet, the reliability of these two techniques is greatly affected by the omnipresent water vapor in the atmosphere. Several criteria are currently in use as quality controls to ensure the protein absorption spectrum is negligibly affected by water vapor interference. In this study, through a second derivative study of liquid water, we first argue that the previously established criteria cannot guarantee a reliable evaluation of water vapor interference due to a phenomenon that we refer to as sample’s absorbance-dependent water vapor interference. Then, through a comparative study of protein and liquid water, we show that a protein absorption spectrum can still be significantly affected by water vapor interference even though it satisfies the established criteria. At last, we propose to use the comparison between the second derivative spectra of protein and liquid water as a new criterion to better evaluate water vapor interference for more reliable second derivative and FSD treatments on the protein amide I band.
Keywords: FTIR spectroscopy; vibrational spectroscopy; protein secondary structure; second derivative; Fourier self-deconvolution
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MDPI and ACS Style

Zou, Y.; Ma, G. A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy. Int. J. Mol. Sci. 2014, 15, 10018-10033.

AMA Style

Zou Y, Ma G. A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy. International Journal of Molecular Sciences. 2014; 15(6):10018-10033.

Chicago/Turabian Style

Zou, Ye; Ma, Gang. 2014. "A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy." Int. J. Mol. Sci. 15, no. 6: 10018-10033.

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