Abstract
The paper presents the results of a chemometric analysis with the aim of highlighting the differences between the double- and single stranded DNA by using Rayleigh Light Scattering (RLS) spectra.
The spectra were obtained by exciting the aqueous solutions of calf thymus DNA in the presence of a molecular probe (the Terbium chelate of the diethylenetriaminopentaacetic acid – Tb-DTPA). Each spectrum consisted in 400 points representing the measured intensities in the range 200-400 nm, with a 0.5 nm step.
The paper presents two kinds of chemometric analysis: Principal Component Analysis (PCA) and Independent Component Analysis (ICA). PCA is well known for its ability in confining the information in a reduced number of uncorrelated coefficients, whilst ACI – lesser used in chemometrics – refines the analysis by imposing the condition of statistically independent components. Both PCA and ICA were used to reduce the dimension of each spectrum to two components. The two-dimensional representation of these components puts a into evidence a clusterisation of the spectra following the excitation wavelength and, for the same excitation wavelength, a separation tendency between spectra belonging to a different kind of DNA (single-stranded and double-stranded).