Browsing by Author "Onogi, Chikao"

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In Vivo Resonance Raman Detection of Ferrous Cytochrome c from Mitochondria of Single Living Yeast Cells
(2010-03-05)
Onogi, Chikao
;
Hamaguchi, Hiro-o
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
Raman spectra of mitochondria in living budding yeast cells (zygote of Saccharonlyces cerevisiae and Saccharomyces bayanus) have been recorded with 532 nm excitation. Strong and sharp Raman bands are observed at 1584, 1315, 1129, 749, and 601 cm(-1), in addition to known phospholipid bands. These Raman bands are not observed in the corresponding Raman spectrum of mitochondria obtained with 632.8 nm excitation. Their peak positions and relative intensities agree excellently with the reported resonance-enhanced Raman bands of ferrous cylochrome c, which has a Q-band absorption at 520 nm. We have thus succeeded in detecting ferrous cytochrome c, one of the key intermediates in the electron-transport chain in mitochondria, in vivo without any pretreatment. In vivo resonance Raman detection of ferrous cytochrome c opens up new possibilities for real-time and quantitative tracing of respiration dynamics in mitochondria in a single living cell.
Photobleaching of the "Raman Spectroscopic Signature of Life" and Mitochondrial Activity in Rho(-) Budding Yeast Cells
(2009-08-06)
Onogi, Chikao
;
Hamaguchi, Hiro-O
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
Raman spectra of mitochondria in single living budding yeast (zygote of Saccharomyces cerevisiae and Saccharomyces bayanus) cells have been measured and compared for two types of tetraploid strains, the wild-type strain and the rho(-) strain. The "Raman spectroscopic signature of life", a strong Raman band at 1602 cm(-1) that sharply reflects the mitochondrial activity, has been found in both of the two strains with similar intensities. This signature showed photobleaching under irradiation of the 632.8 nm line of a He-Ne laser, only for the rho(-) strain. The photobleaching recovered by keeping the cell in the dark for two hours without laser irradiation. These findings indicate that the molecular species that gives rise to the 1602 cm(-1) band is an intermediate formed and accumulated during the metabolic cycle and that it absorbs at 632.8 nm to undergo photodecomposition. We also found a number of weak Raman bands in the 400-1200 cm(-1) region that show the same temporal behaviors as that of the 1602 cm(-1) band by an SVD analysis of time-resolved Raman spectra, Several new pieces of information oil the origin of the "Raman spectroscopic signature of life" have thus been obtained.
Raman Spectra of Isotope-substituted Mitochondria of Living Budding Yeast Cells: Possible Origin of the "Raman Spectroscopic Signature of Life"
(2009-09-05)
Onogi, Chikao
;
Torii, Hajime
;
Hamaguchi, Hiro-o
;
應用化學系
;
應用化學系分子科學碩博班
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(-1) that sharply reflects the metabolic activity of living yeast cells. The band shifts to 1542 cm(-1) with (13)C substitution and to 1599 cm(-1) with (2)H substitution. Normal mode analysis based oil 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(-1) band.