The chlorophylls in vivo and in vitro

Abstract

This chapter presents the distribution of the chlorophylls. The distribution of the different chlorophylls among the various divisions of organisms that carry out photosynthesis with evolution of oxygen follows a regular and evolutionary conservative pattern that, with a few exceptions, corresponds to that found in the classification of these organisms by other taxonomic criteria. By contrast, the photosynthetic bacteria have a much more irregular pattern of chlorophyll distribution. Different chlorophylls may even be found in different isolates of what has been considered the same species. The principal problem at present in studies of chlorophyll distribution, both in bacteria and in higher organisms, appears to be the relation of the various isomeric forms of the chlorophylls, and of the chlorophyll derivatives, found in extracts to the functional pigments of the living cell. As there are pronounced variations in the absorption bands of the chlorophylls in different organisms, careful comparative studies should make it possible to decide whether these isomers and derivatives are responsible for the variations in chlorophyll absorbance in vivo and for some of the functionally different chlorophyll complexes of photosynthetic organisms.