Raman optical activity applied to biological systems

Abstract

Introduction Raman Optical Activity (ROA) provides information about of chirality in molecules with high relevance for health area. In the present work, we implemented new technique to measure the ROA spectra of chiral molecules per Raman Spectroscopy by Ellipsometry (RaSE). ROA quantifies the small difference in the intensity of Raman scattering for chiral molecules in incidence of polarized circularly laser light and RaSE measures the Raman scattering by Stokes parameters, which describe the polarization state of light. Purpose Study of L. infantum parasite the etiological agent of Visceral Leishmaniasis by RaSE technique. Materials and methods DNA sample of L. infantum was extracted of a crop from parasite in the promastigote phase in according to the manual procedure of extraction kit user NucleoSpin® Tissue – Genomic DNA from Tissue, Chapter. 5: Standard protocol for human or animal tissue and cultured cells. This procedure provided us a DNA concentration S = 17,5 ng/μL and V = 50 μL. RaSE spectra were obtained as excitation light linear in polarization set up that can be decomposed in two circular polarization to obtain Stokes parameters that describes the signal ROA. Results Raman spectra showed vibration bands in the range of 400–1700 cm−1 corresponding to DNA constituents. S3 Stokes parameter indicated a chirality preponderance of LCP light over RCP light. Conclusion Raman spectra assigned vibration mode of DNA and indicated a chirality preponderance. We will study L. infantum by RaSE-ROA in order to obtain information on the structure that is lost with the use of other techniques.