Reproducibility of the nonlinear regression fit to the FTIR spectra of lysozyme.
Controversy exists concerning the influence of experimental artifacts on the number of component FTIR vibrational bands which may be resolved from the amide I and II envelopes of proteins in water. Whether these bands represent unique populations of vibrating protein groups in a particular global 2 degrees structure or whether the bands are due to instrumental and environmental fluctuations has been addressed, T.F. Kumosinski and J.J. Unruh, Talanta, 43 (1996) 199-219. The repeatability of the methodology and the apparent uniqueness of the nonlinear regression fits are addressed in this study. We obtained a series of the spectra of lysozyme, and carried-out nonlinear regression analysis of each spectrum. Coefficients of variation (COV) were calculated for the wavenumber and area values of assigned component peaks obtained. Low COVs obtained attest to the precision of the methodology and the apparent uniqueness of the nonlinear regression fits. This methodology for acquisition and analysis of protein FTIR spectra yields results with good precision.
Kumosinski
T F
TF
U.S. Department of Agriculture, ARS, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
Unruh
J J
JJ
Farrell
H F
HF