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 protochlorophyll in the etioplast inner membranes isolated from leaves of wheat (Triticum aestivum cv. Kosack). The emission spectra were recorded with various excitation wavelengths between 400 and 500 nm. The excitation spectra were recorded for fluorescence emitted at various wavelengths between 620 and 740 nm. The spectra were analysed by a combination of various computer-aided methods including differential analysis, gaussian resolution and topological plots. The four pigment forms can be characterized by their different excitation (Ex) and emission (Em) bands. Adding the satellite bands of the Qy(0-0) transitions, the emission vibrational (Emv) bands, with correlated amplitudes gave the following delineation: Ex436-Em633-Emv690, Ex443-Em645-Emv711, Ex451-Em657-Emv727, and Ex463-Em671-Emv740. The differences in the spectral properties of the four pigment forms are discussed in relation to possible differences in their structural arrangement, association to NADPH-protochlorophyllide oxidoreductase and localization in prolamellar bodies and/or prothylakoids.