Fluorescence Spectrophotometry 

 of Photosynthetic Pigments 



C. Stacy French 

 Department of Plant Biology, Carnegie Institution of Washington, 



Stanford, California 



Absorption spectrophotometry has played a large part in the develop- 

 ment of modern biochemistry. Fluorescence spectrophotometry, on 

 the other hand, has not been used as widely because there are many 

 more substances that can absorb light than can reemit fluorescent 

 light; furthermore, the measurements are somewhat more difficult to 

 make. However, in suitable cases the value of fluorescence spectro- 

 photometry equals or exceeds that of absorption spectrophotometry 

 for pigment identification in live cells and in extracts and for quanti- 

 tative analysis. Also, it is ideally suited to the study of energy transfer 

 between pigments. 



During the course of an investigation on energy transfer between 

 the pigments of red algae it became apparent that the basic data avail- 

 able on the fluorescence spectrophotometry of photosynthetic organ- 

 isms and of their purified pigments is very meager. The spectrophoto- 

 graphic location of fluorescence peaks determined largely by Dhere 

 has been reviewed by Rabinowitch (1951). Vermeulen, Wassink, and 

 Reman ( 1937 ) measured the fluorescence energy distribution curves 

 of Clilorella, the purple bacterium Chromatium, a plant extract con- 

 taining chlorophyll a and b and an extract of purple bacteria con- 

 taining bacteriochlorophyll. Zscheile and Harris ( 1943 ) made precise 

 measurements of the fluorescence spectra of pure chlorophylls a and 

 b in various solvents. Van Norman, French, and Macdowall ( 1948 ) 

 measured the fluorescence curves of two red marine algae and of a 

 water extract from one of them. Duysens (1951) published the 



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