Selective Observation of Chlorophyll c in Whole Cells of Diatoms by Resonant Raman Spectroscopy

Abstract

A surface scanning technique was used to obtain resonant Raman spectra from chlorophylls in solution and in whole cells of diatoms at 80 K. When in vivo samples are excited at 457.9 nm, chlorophyll c becomes observable in the recorded Raman spectra, as shown by comparison with in vitro measurements. In the field of photosynthetic research this becomes Interesting, as chlorophyll c can hardly be detected in electronic absorption spectra from whole cells, even at low temperatures, because of its weak Q bands compared with other plant chlorophylls. Chl a spectra were obtained with the use of 441.6-nm excitation. Working with two-channel recording, we eliminated the solvent contribution from the Raman spectra of pigments in vitro. Moreover, the technique facilitates detection of Raman excitation profiles from pigment lines in vivo at low temperatures by use of a nonresonating reference in the second sample chamber.

Carotenoid Structures and Environments in Trimeric and Oligomeric Fucoxanthin Chlorophyll a/c2Proteins from Resonance Raman Spectroscopy

“…In IR spectra, where carbonyl bands are much stronger, the unconjugated acetate CdO is at 1732 cm -1 whereas the C8dO group of Fx is at 1654 cm -1 . 29 In the RR spectra, the weak band at 1630-1660 cm -1 (Figure 2) is also attributed to the C8 carbonyl, 27,30,31 which, moreover, exhibits a downshift in a polar (protic) solvent versus a nonpolar (toluene) solvent. The broader carbonyl band in Fx Acn and Fx MeOH , relative to Fx Tol , could be attributed to greater inhomogeneous broadening in polar environments.…”

Raman Spectroscopy of Algae: A Review

“…Algae cell contains mainly five types of biomolecules: proteins, carbohydrates, lipids, nucleic acids and pigments [18]. Raman spectroscopy has been used to find the molecular structure of the biomolecules [34][35][36][37][38][39][40][41][42][43] and to analyze other properties such as the location of biomolecules in the cell [16,[44][45][46][47][48][49][50][51][52]. Various methods are used to predict the molecular structure of biomolecules using Raman spectroscopy.…”

Modelling heme d1

“…The latter, known to be conjugated as judged from electronic absorption spectra [19], introduces both ester and olefin modes. An acrylate is not a common substituent of biological tetrapyrroles; its only other occurrence is on the D-ring of chlorophylls c [20].…”