Spectral forms of protochlorophyllide in prolamellar bodies and prothylakoids fractionated from wheat etioplasts

The relation between the different protochlorophyllide (PChlide) forms in isolated etioplast inner membranes was dependent on the concentration of sucrose and NADPH in the isolation media. Etioplasts were prepared from wheat ( Triticum aestivum L. cv. Starke II, Weibull) by differential centrifugation. The etioplasts were freed of envelope and stroma and the etioplast inner membranes were exposed to a concentration series of sucrose. Fluorescence emission spectra revealed a positive correlation between the emission ratio 657/633 nm and the sucrose concentration in which the membranes were suspended. Addition of NADPH prevented the degradation of 657 nm emission caused by low sucrose concentrations. PChlide already altered to PChide 628–632 could not re‐form PChlide 650–657 after the addition of NADPH in darkness. Prolamellar bodies and prothylakoids were separated in a bottom‐loaded sucrose density gradient in the presence of NADPH. The dominating PChlide‐protein complex in the prolamellar bodies was PClide 650–657 . Only minor amounts of PChlide 628–632 were found in these membranes. The prothylakoids had a higher content of PChlide 628–632 , relative to PChlide 650–657 , than the prolamellar bodies, as judged from absorption and fluorescence spectra. After phototransformation the fluorescence emission at 633 nm increased relative to the emission from phototransformed PChlide indicating an efficient energy transfer between PChlide 628–632 and PChlide 650–657 before irradiation.