Analysis of Fluorescence-Scattering Spectra for Certain Nucleoprotein - Terbium Chelate Complexes

摘要

Chemometrics gained in the last two decades a well defined place among the methods used to assess the quality of different materials,mainly in the cosmetics,pharmaceutical and food industry.These methods replace the classic,univariate way of measuring and interpreting the experimental data with a multivariate way of analysing experimental signals obtained nowadays by using instrumental methods (mainly spectroscopy and chromatography).Principal Component Analysis (PCA) is the mostly used multivariate statistical analysis used to limit to a suitable value the number of parameters further used in different pattern recognition type techniques.The purpose of the study was to use PCA and cluster analysis to emphasize differences between double- and single- stranded DNA by means of the Rayleigh scattering (RLS) and fluorescence resonance energy transfer (FRET) spectra of the complexes made between the nucleoprotein and the terbium chelate of the diethylentriaminopentaacetic acid (Tb-DTPA).Experiments have been performed on aqueous double- and single- stranded calf thymus DNA,having in view both the fluorescence and the scattering spectra.PCA permits to differentiate the denatured DNA molecule from the native one by using the RLS,FRET or combined RLS-FRET spectra,mainly when excited at 255 nm and 285 nm.Only the last two principal components have been used,as they gather more than 80% of the information contained in the spectra.PCA also permits to identify errors in the scanning process (e.g.errors of the instrumental parameters used).