Irradiation of an etioplast inner membrane fraction caused the transformation of two photoactive spectroscopically different protochlorophyllide forms into two chlorophyllide forms. A weak light flash, 6% of a saturating Hash, preferentially caused the formation of a short wavelength chlorophyllide form absorbing at 672 nm and emitting at 676 nm. A saturating flash resulted in the formation of the 684 nm absorbing form of chlorophyllide with an emission maximum at 698 nm.The circular dichroism (CD) signals of the newly formed chlorophyllide forms indicated that thcy are pigment aggregates of different sizes. These aggregates are probably connected to protochlorophyllide reductase and NADPH or NADP. In the absence of NADPH a decomposition of the pigment aggregates took place as revealed by a decrease in the CD-signal. A model is suggested which describes the structural changes of the pigment-protein aggregates after irradiation.

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Protochlorophyll forms in roots of dark-grown plants. Protochlorophyll was found in roots of dark-grown piants of seven species investigated. It was identified by absorbance and fluorescence spectra of acetone and ether extracts. Chlorophyll was aiso found in roots of one pea species. The concentration of protochlorophyll was usually highest in young root tips and decreased upwards along the roots. The maxima of the in vivo absorbance spectra of the species studied varied hetween 634 and 638 nm. Low temperature in vivo fiuorescencc emission spectra had two maxima, one at ca 633 and the other at ca 642 nm, when the wavelengths of the excitation light were 440 and 460 nm, respectively. In vivo fluorescence excitation spectra displayed a shift of the excitation maximum from 438 to 445 nm, when emission varied from 620 to 647.5 nm. Deconvolutlon of these three types of spectra into Gaussian components made it possible to identify two spectral forms of protochlorophyll: protochlorophyH,,^,:, and protochlorophylljj,_Mi.

Leaves and chloroplast suspensions of severely and slightly iron deficient cucumber (Cucumis sativus L.) plants were characterized by low‐temperature fluorescence emission spectroscopy and Deriphat polyacrylamide gel electrophoresis. The emission spectra of the chloroplast suspensions were resolved into Gaussian components and those changes induced by iron deficiency were related to the variations in the chlorophyll‐protein pattern. The symptoms described with these methods were also correlated with the iron content of the leaves. It was concluded that the lack of physiologically active iron caused a relative decrease of photosystem I (PSI) and light harvesting complex I (LHCI), together with the long wavelength fluorescence, especially the 740 nm Gaussian component, and. to a much lesser extent, of the photosystem II (PSII) core complexes (relative increase of 685, 695 nm components). However, the relative decrease in the amount of light harvesting complex II (LHCII) was followed by a relative increase in its fluorescence band at 680 nm, showing that energy transfer from LHCII to core complex II (CCII) was partly disturbed. Thus iron deficiency affected the photosynthetic apparatus in a complex way: it decreased the synthesis of chlorophylls (Chls) and influenced the expression and assembly of Chl‐binding proteins.

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