| Two analytical methods were applied to photosynthetic materials for the first time. First, measurements of prompt and delayed fluorescence were used to quantify the amount of free energy available to photosystem-II in the alga Scenedesmus quadricauda during illumination, and to see how effectively it is stored afterwards. It was found that following illumination with light of physiological intensity, a potential of approximately 1.0 volt was maintained by components of the electron transport chain for about 1 second, after which it fell to 0.7 volts. This new potential appeared to be maintained indefinitely. It was also found that the potential during illumination was usually 0.13 volts higher in free energy than that immediately following illumination.;Second, factor analysis was used as a method to extract spectroscopic information about photosynthetic complexes. Isolated photosystem-I particles had a maximum of three independently absorbing and emitting species. Chloroplasts and whole algae exhibited only two. The emission spectrum attributed to photosystem-I in chloroplasts was noticably different from that of algae. In general, the results obtained seem consistent with what is known in the literature. The advantages of this method would be to limit the amount of purification necessary, which can introduce artifacts, to study systems which cannot be physically separated, and to avoid the use of liquid nitrogen temperatures. |
