ESSENTIAL QUALITY CONTROL INVESTIGATIONS OF CHIROPTICAL SPECTROSCOPY DATA OF BIOLOGICAL MOLECULES
Dhia Elhag*, Ali Aboel Dahab, Zuheir Osman
ABSTRACT
Circular Dichroism (CD) has become one of the most important techniques for the characterization of biomolecules, determination of absolute configuration and stereochemical analysis. However, literature lacks data related to quality assurance/control of factors affecting the reliability of chiroptical spectroscopic data. Therefore, it is important, prior to the analysis, to establish quality assurance for these factors affecting the reliability of the data, which is especially true when spectra are crucial evidence of the structure and stability of a protein component of a pharmaceutical product, but it is also important when spectra are to be reported for almost any purpose. Nevertheless, to ensure good circular dichroism data that are comparable between
instruments and between laboratories, there are several major factors in an optical spectrometer that need to be controlled including calibration (intensity and wavelength calibration), data resolution spectral bandwidth (SBW), time scale of measurements and scan mode. Moreover, signal and noise, post measurement smoothing, stray light, drift, performance characteristics and experimental factors. In this work, we have studied the effect of several factors on the quality of spectral data of proteins (IgG), amino acids (L-phenylalanine) and simulated spectra of nucleic acid. The results showed that increasing the wavelength stepsize distorts the spectrum and can produce a reduced peak height i.e. loss of fine structure. In terms of signal processing, the fewer the steps needed the longer is the time spent averaging the data at a particular wavelength and hence the lower the noise associated with the spectroscopic feature.
Keywords: Calibration; chiroptical spectroscopy; circular dichroism; quality control.
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