Controversy exists concerning the influence of experimental artifacts
on the number of component FTIR vibrational bands which may be resolve
d from the amide I and II envelopes of proteins in water. Whether thes
e 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. K
umosinski and J.J. Unruh, Talanta, 43 (1996) 199-219. The repeatabilit
y of the methodology and the apparent uniqueness of the nonlinear regr
ession fits are addressed in this study. We obtained a series of the s
pectra of lysozyme, and carried-out nonlinear regression analysis of e
ach spectrum. Coefficients of variation (COV) were calculated for the
wavenumber and area values of assigned component peaks obtained. Low C
OVs obtained attest to the precision of the methodology and the appare
nt uniqueness of the nonlinear regression fits. This methodology for a
cquisition and analysis of protein FTIR spectra yields results with go
od precision. (C) 1997 Elsevier Science B.V.