Chlorophyll Formation in the YG-6 Mutant of Chlorella regularis: Accumulation of Protochlorophyllide and Protochlorophyll Esterified with Geranylgeraniol

A chlorophyll-less mutant, YG-6, was produced by UV treatmentof the wild strain of Chlorella regularis (S-50). Cells grownfor 3 days in darkness showed a red absorption maximum at 634nm and a shoulder near 650 nm, indicative of the accumulationof at least two spectral forms of protochlorophyll(ide). Protochlorophyllide(Pchlide), and one species only of Pchlide ester, protochlorophyllesterified with geranylgeraniol (Pchl GG) were separated, thelatter with absorption maxima in diethyl ether at 438, 574 and624 nm. Spectroscopically, Pchl GG was identical with divinyl-protochlorophyll.The content of Pchlide was 10 to 13 times that of Pchl GG. Bothpaper and high-performance liquid chromatography showed thephototransformation of Pchlide, but no Pchl GG was present.This suggests that Pchl GG is not a direct precursor of chlorophylla esterified with geranylgeraniol. (Received June 4, 1983; Accepted November 11, 1983)