FLUORESCENCE RESPONSES OF CHLOROPHYLL IN VIVO TO TREATMENT WITH ACETONE.

Abstract

Fluorescence properties of isolated chloroplasts were studied in acetone-buffer mixtures of various concentration as well as during extraction. It was found that: When increasing the acetone concentration, the fluorescence band shifts to the short-wave side. Three concentration ranges are to be distinguished: the first one, 0–30%, causes only a slight shift, the second one, 30–50%, effects a considerable shift, whereas in the remaining range, the location of the band of dissolved chlorophyll is attained. The fluorescence yield depends on acetone concentration in a different way: in the 0–20% region it rises, then it drops around 30%, next it rises considerably until around 80% this yield reaches the value typical of dissolved chlorophyll. As evidenced by a shift of the fluorescence band to the long-wave side, reduction of an acetone concentration from 80% to 20% in the suspension medium of chloroplasts effects at least a partial recombination of chlorophyll and carrier. However, it is doubtful whether the produced complexes are identical with the naturally occurring ones. By means of a flow technique, the fluorescence time course was studied during chlorophyll removal from its carrier by 80% acetone. The results are in line with the earlier mentioned static data. Such a time course, however, differs markedly from that obtained with colloidal chlorophyll. Recombination experiments, performed with the flow technique, demonstrated that the fluorescence time course during formation of chlorophyll-carrier complexes follows a pattern different from the reverse of that of the just mentioned process. The results are discussed. They suggest that the structure of the naturally chlorophyll a types is rather specific.