Mg2+ Induced Fluorescence Change in Relation to Thylakoid Surface Electric Charge in Two Varieties of Soybean Chloroplasts

The effects of Mg2+ concentration on chlorophyll a light-in-duced variable fluorescence and eleetrophoretie velocity of chloroplasts obtained from two varieties of soybean (Ji-Pei No. 1 and Feng-Shou Yellow) were recorded. The light induced variable fluorescence yield and the eleetrophoretie mobility of two kinds of ehloroplasts in the suspending medium containing low level of salt differs from each other. But, the fluorescence yield of chloroplast membranes from two varieties of soybean is relative to that of eleetrophoretic mobility. The pattern of kinetic change of Mg2+ induced variable fluorescence intensity is similar to that of eleetrophoretie mobility. The optimum concentrations of Mg2+ required for the effect on chlorophyll fluorescence and the electrophoretie velocity change are also similar These results indicate that Mg2+ induced excitation energy distribution change between the two photosystems is intimately related to Mg2+-indueed alteration of thylakoil membrane surface eleetrostat.ie property. The possible role of earboxyl group of proteins on Mg2+ induced effects has been discussed in this paper.