Considerations of Noise and Measurement Reproducibility of Circular Dichroism Measurements Using Na[Co^III(EDDS)]

Abstract

Although circular dichroism (CD) spectroscopy has become ubiquitous in biological, chemical, and pharmacological laboratories, several issues with instrument calibration and standardization, measurements quality, and reproducibility still remain. In the context of validating and developing a wide-wavelength-range stable standard for CD that is available in both enantiomeric forms, (R,R)- and (S,S)-Na[Co(III)(EDDS)] (where EDDS is ethylenediaminedisuccinato), we have become aware of sources of error in CD spectroscopy in addition to instrument calibration and user issues. This article summarizes those errors and suggests procedures for minimizing them by averaging over sufficient independent data accumulations with appropriate parameters.

Bayesian inference assessment of protein secondary structure analysis using circular dichroism data – how much structural information is contained in protein circular dichroism spectra?

“…There are a few exceptions, such as neural network model approaches, [15][16][17] though the self-organising map neural network approaches also involve finding a best match combination of spectra and assigning secondary structures from them. The implicit assumption behind a linear model is that the errors at each wavelength are uncorrelated and have equal variance, even though evidence for a more complicated error structure has been recently pointed out, 18 with variance depending on the wavelength. There are also significant amounts of correlation within some parts of the spectrum.…”