Syntheses of {delta}-aminolevulinic acid and chlorophyll during chloroplast formation in Chlorella protothecoides

Greening cells of Chlorella prolothecoides were assayed foractivity of the in vivo synthesis of ALA, which was markedlydeveloped during light-induced greening. Effects of CH on thesyntheses of ALA and chlorophyll were also examined. The resultsstrongly suggested that a labile enzyme is involved in ALA synthesis,and that continuous formation of the enzyme is required forthe greening of cells. However, the prompt suppression of chlorophyllsynthesis when CH was added to rapidly greening cells was foundto be attributable not to the blockage of ALA synthesis butto the suppression of some later process(es) in the course ofchlorophyll synthesis, under the conditions used. The valueof the Hill coefficient for the CH inhibition of chlorophyllsynthesis as well as the CH concentration which caused 50% inhibitionremained unaltered whether it was measured when the ALA synthesisactivity was greatly inhibited by CH or when the activity wasonly slightly suppressed. (Received November 11, 1974; )