Raman Spectra of Isotope-substituted Mitochondria of Living Budding Yeast Cells: Possible Origin of the “Raman Spectroscopic Signature of Life”

Abstract

The 13 C and 2 H isotope substitution effects have been examined for the ''Raman spectroscopic signature of life,'' a mitochondrial Raman band at 1602 cm À1 that sharply reflects the metabolic activity of living yeast cells. The band shifts to 1542 cm À1 with 13 C substitution and to 1599 cm À1 with 2 H substitution. Normal mode analysis based on a DFT calculation suggests that it originates from a C=C double bond having no hydrogen atoms attached to the carbon atoms. The in-phase C=C stretch mode of ubisemiquinone radicals (CoQ and/or CoQH ) emerges as a strong candidate for the origin of the 1602 cm À1 band.

Molecular component distribution imaging of living cells by multivariate curve resolution analysis of space-resolved Raman spectra

“…In the past two decades, a number of publications have shown the successful application of Raman microspectroscopy to label-free molecular-level analysis of living cells and to discrimination of cell types. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Although Raman spectra contain rich information on molecular structure, detailed interpretation of measured spectra is often difficult because of their complexity. Each Raman spectrum obtained from space-resolved mapping measurements is usually interpreted as a superposition of several spectral components of biomolecules, as well as a background and fluorescence.…”

Photobleaching of the resonance Raman lines of cytochromes in living yeast cells

“…The potential of Raman spectroscopy for characterization the cell activity was demonstrated recently by series of studies [20][21][22][23]. Another outstanding application of the Raman spectroscopy for cells is the studies of the Raman spectra of cytochromes [24][25][26][27][28][29][30][31][32][33].…”

The “Raman spectroscopic signature of life” is closely related to haem function in budding yeasts

“…Isotope substitution experiments also showed that the signal originates from a C=C double bond structure [15]. The information above has helped us to finally propose sev- eral specific candidates of the "Raman spectroscopic signature of life" and we hope that the true origin of the signal will be elucidated soon.…”