ANALYSIS OF THE 77-K FLUORESCENCE EMISSION AND EXCITATION-SPECTRA OF ISOLATED ETIOPLAST INNER MEMBRANES

Low-temperature fluorescence emission and excitation analyses revealed four discrete spectral forms of protochlorophyllide and/or protochlor ophyll in the etioplast inner membranes isolated from leaves of wheat (Triticum aestivum cv. Kosack). The emission spectra were recorded wit h various excitation wavelengths between 400 and 500 nm. The excitatio n spectra were recorded for fluorescence emitted at various wavelength s between 620 and 740 nm. The spectra were analysed by a combination o f various computer-aided methods including differential analysis, gaus sian resolution and topological plots. The four pigment forms can be c haracterized by their different excitation (Ex) and emission (Em) band s. Adding the satellite bands of the Qy(0-0) transitions, the emission vibrational (Emv) bands, with correlated amplitudes gave the followin g delineation: Ex436-Em633-Emv690, Ex443-Em645-Emv711, Ex451-Em657-Emv 727, and Ex463-Em671-Emv740. The differences in the spectral propertie s of the four pigment forms are discussed in relation to possible diff erences in their structural arrangement, association to NADPH-protochl orophyllide oxidoreductase and localization in prolamellar bodies and/ or prothylakoids.