311
11 Structural and Spatial Analysis of Carotenoids in a Single Cell monitored …
carotenoids of similar vibrational signature [19], distinguish cells grown in different
environmental conditions [13–15], and find differences between carotenoid composition in different species [15]. Possibility of the application of Raman microspectroscopy to study a single cell rather than bulk sample is of high importance due to
observed heterogeneity of cellular populations in unicellular species [20, 21].
Quantum-chemical calculations have been formerly applied to solve various
structure-related problems related to carotenoids, such as reaction dynamics of
carotenoids as antioxidants [22], various aspects of carotenoid reactivity in light
harvesting complexes [23–26], or a batochromic shift of protein-bound carotenoid
astaxanthin [27, 28]. It is, however, necessary to underline that carotenoids, 40 carbon atoms molecules, are computationally demanding even with the application
of powerful computing resources and fast dFt algorithms. the additional complication, difficult to account for in computations, is a significant change of pigment structures in biological environment as demonstrated for instance by abovementioned significant batochromic shift of protein-bound astaxanthin compared
to a non-bonded standard [27, 28]. therefore, the quantum-chemical modeling of
carotenoids in the biological context, including cells and tissues, is rather scarce.
Examples of such studies, illustrating the potential of quantum-chemical methods
to successfully solve structural problems of bound-carotenoids, are investigations
of the structure and distribution of astaxanthin in a unicellular alga Haematococcus
Pluvialis, also upon the temperature stress [29, 30].
the chapter is divided in three parts. the first section is devoted to studies of
structure and cellular distribution of carotenoids in unicellular organisms, producing these pigments de novo. the second section covers works related to the application of Raman spectroscopy to study carotenoids in plant and animal (non-human)
cells and finally, the third section reviews research in which Raman spectroscopy
and imaging were used to analyze these pigments in human healthy and pathogenic
cells.
11.2 Raman Imaging of Unicellular Organisms
Considerable attention has been focused on carotenoids in unicellular organisms
producing these pigments de novo with Raman microspectroscopy and microimaging being very effective methods to study these micro-scale systems. Some of the
works in this area are purely experimental and they will be referred briefly below.
Examples of the successful match between experimental and computational (both in
the sense of the application of quantum-chemical and chemometric methods) strategies in the studies of unicellular organisms are described at the end of the chapter.
Kubo et al. [31] applied Raman mapping and polarized Raman spectroscopy to
determine distribution of pigment molecules and their orientation, respectively, in a
single cell of Euglena gracilis and Chlamydomonas reinhardtii. the observed Raman signal was derived solely from carotenoids, although the pigment(s) were not
specified. Integration of the marker band at 1530 cm
−1
allowed for localization of
11 Structural and Spatial Analysis of Carotenoids in a Single Cell monitored …
carotenoids of similar vibrational signature [19], distinguish cells grown in different
environmental conditions [13–15], and find differences between carotenoid composition in different species [15]. Possibility of the application of Raman microspectroscopy to study a single cell rather than bulk sample is of high importance due to
observed heterogeneity of cellular populations in unicellular species [20, 21].
Quantum-chemical calculations have been formerly applied to solve various
structure-related problems related to carotenoids, such as reaction dynamics of
carotenoids as antioxidants [22], various aspects of carotenoid reactivity in light
harvesting complexes [23–26], or a batochromic shift of protein-bound carotenoid
astaxanthin [27, 28]. It is, however, necessary to underline that carotenoids, 40 carbon atoms molecules, are computationally demanding even with the application
of powerful computing resources and fast dFt algorithms. the additional complication, difficult to account for in computations, is a significant change of pigment structures in biological environment as demonstrated for instance by abovementioned significant batochromic shift of protein-bound astaxanthin compared
to a non-bonded standard [27, 28]. therefore, the quantum-chemical modeling of
carotenoids in the biological context, including cells and tissues, is rather scarce.
Examples of such studies, illustrating the potential of quantum-chemical methods
to successfully solve structural problems of bound-carotenoids, are investigations
of the structure and distribution of astaxanthin in a unicellular alga Haematococcus
Pluvialis, also upon the temperature stress [29, 30].
the chapter is divided in three parts. the first section is devoted to studies of
structure and cellular distribution of carotenoids in unicellular organisms, producing these pigments de novo. the second section covers works related to the application of Raman spectroscopy to study carotenoids in plant and animal (non-human)
cells and finally, the third section reviews research in which Raman spectroscopy
and imaging were used to analyze these pigments in human healthy and pathogenic
cells.
11.2 Raman Imaging of Unicellular Organisms
Considerable attention has been focused on carotenoids in unicellular organisms
producing these pigments de novo with Raman microspectroscopy and microimaging being very effective methods to study these micro-scale systems. Some of the
works in this area are purely experimental and they will be referred briefly below.
Examples of the successful match between experimental and computational (both in
the sense of the application of quantum-chemical and chemometric methods) strategies in the studies of unicellular organisms are described at the end of the chapter.
Kubo et al. [31] applied Raman mapping and polarized Raman spectroscopy to
determine distribution of pigment molecules and their orientation, respectively, in a
single cell of Euglena gracilis and Chlamydomonas reinhardtii. the observed Raman signal was derived solely from carotenoids, although the pigment(s) were not
specified. Integration of the marker band at 1530 cm
−1
allowed for localization of