Nonpigment components of the protochlorophyllide photoactive complex: Studies of low-temperature blue-green fluorescence spectra

Comparative investigation of fluorescence spectra in the blue-green region and excitation fluorescence spectra of green wheat leaves, etiolated wheat leaves and isolated inner etioplast membranes (prolamellar bodies and proth ylakoids) was carried out to specify the structure of active protochlorophy llide pigment-protein complex of the inner etioplast membranes. Three bands were found (in the blue region) of the spectra at 420, 443 and 470 nm and a broader green band at 525 nm. Comparison of the emission and excitation s pectra allows us to suggest that the main compounds responsible for the blu e fluorescence of the etioplast inner membranes are pyridinenucleotides and pterins. The green fluorescence (525 nm) excitation spectra of etiolated s amples were identical to the excitation spectrum of the flavins fluorescenc e. The fact confirms the suggesition that flavins are the constituents of t he active protochlorophyllide-protein complex.