Of photosynthetic pigments

The isoprenoid hycrocarbons pristane and phytane (derived from the phytol side chain of chlorophyll), as well as porphyrins, have been detected in organic extracts of the Nonesuch Shale of 1.1 billion year age [23]. Their presence points to the existence of photosynthetic pigments in the Precambrian era, but it is also possible that these extractable substances could have been contributed to the rock at a later time. However, in this instance contamination appears to be less likely on account of the large abundance of organic material in this shale. 

R. Boyer, Biocbem. Educ. 18, 203-206 (1990), Isolation and Spectrophotometric Characterization of Photosynthetic Pigments. ... 

The transfer of photosynthetic pigments from a larger extract in an aqueous organic solvent by a small amount of a hydrophobic organic solvent concentrates the pigments. 

For comparison with other plant samples, take 0.05 or 0.1 ml of this concentrated pigment extract, dilute to 5 ml with 100% acetone or diethyl ether, and determine the amount of photosynthetic pigments using the absorption coefficients and equations given in UNITF4.3. 

Extraction of photosynthetic pigments can be carried out using a mortar and pestle or a... 

Jeffrey, S.W. (1974) Profiles of photosynthetic pigments in the ocean using thin-layer chromatography. Mar. Biol. 26, 101-110. 

Kennicutt II, M.C., Bidigare, R.R., Macko, S.A., and Keeney-Kennicutt, W.L. (1992) The stable isotopic composition of photosynthetic pigments and related biochemicals. Chem. Geol. 101, 235-245. 

Interestingly, only two types of pigments appear to be involved in all known photochemical reactions in plants and algae. These are the carotenoids and the tetrapyrroles, the latter class including the chlorophylls, the phycobilins, and phytochrome. The maximum absorption coefficients for the most intense absorption bands are slightly over 104 m2 mol-1 in each case, with 7 to 12 double bonds in the main conjugated system. Cytochromes, which are involved in the electron transport reactions in chloroplasts and mitochondria, are also tetrapyrroles (considered later in this chapter). Table 5-1 summarizes the relative frequency of the main types of photosynthetic pigments. 

The first step in photosynthesis is light absorption by one of the pigments. The absorption event (discussed in Chapter 4, e.g., Section 4.2E) for the various types of photosynthetic pigments described in this chapter can be represented as follows ... 

Table 3 Ground and excited singlet state redox potentials of photosynthetic pigments in vitro and in vivo ...

Historically the first X-ray structure [43-45] to undergo exciton analysis was that of the water-soluble BChl a-protein from the green photosynthetic bacterium Prosthecochloris aestuarii. The analysis [16] raised questions, and controversies, that remain unresolved after a decade. It is reviewed again here to emphasize these difficulties, to correct some misconceptions in the literature [4,46,47] regarding possible sources of the difficulties, and to discuss more recent developments. Exciton analysis of photosynthetic pigment-protein complexes is iipt likely to become a truly useful procedure until it produces results that agree with all relevant spectra of this particular complex. 

Hanson LK. Theoretical calculations of photosynthetic pigments. Photochem. Photobiol. 1988 47 903-921. 

Beaumont V. I., Jahnke L. L., and Des Marais D. J. (2000) Nitrogen isotopic fractionation in the synthesis of photosynthetic pigments in Rhodobacter capsulatus and Anabaena cylindrica. Org. Geochem. 31(11), 1075-1085. 

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