Protochlorophyllide Reduction and Greening

This book gathers contributions presented during an In ternational meeting organized by the Laboratory of Photobio logy of the University of Liege, Belgium, on 8 and 9 August 1983. The general topic of the discussions was protochlorophyl lide reduction and greening. Among the reasons for choosing this topic were the recent advances in the field. These ad vances deal with: (1) The characterization of the basic constituents of the photoenzymatic complex responsible for protochlorophylli de reduction. This complex is known to be ternary, comprising the pigment: protochlorophyllide, NADPH and the enzyme proto chlorophyllide oxidoreductase. (2) The discovery of short-lived intermediates in the photoreduction process, and in particular, the recent findings resulting from the proqresses of the picosecond and nanosecond spectrometry. (3) The obtention of new data on the components of the plastids, on the changes they undergo during the first steps of greening, and on the distribution of the pigment-protein complexes between the various substructures of the etioplast. (4) The detection of early photoactivities apart from protochlorophyllide reduction. These subjects have ~cen extensively discussed during the meeting and several sections of this book are devoted to the presentation of the new data.

Proceedings of a Meeting held at the University of Liège, Belgium, 8-9 August 1983

Texte du rabat

This book gathers contributions presented during an In­ ternational meeting organized by the Laboratory of Photobio­ logy of the University of Liege, Belgium, on 8 and 9 August 1983. The general topic of the discussions was protochlorophyl­ lide reduction and greening. Among the reasons for choosing this topic were the recent advances in the field. These ad­ vances deal with: (1) The characterization of the basic constituents of the photoenzymatic complex responsible for protochlorophylli­ de reduction. This complex is known to be ternary, comprising the pigment: protochlorophyllide, NADPH and the enzyme proto­ chlorophyllide oxidoreductase. (2) The discovery of short-lived intermediates in the photoreduction process, and in particular, the recent findings resulting from the proqresses of the picosecond and nanosecond spectrometry. (3) The obtention of new data on the components of the plastids, on the changes they undergo during the first steps of greening, and on the distribution of the pigment-protein complexes between the various substructures of the etioplast. (4) The detection of early photoactivities apart from protochlorophyllide reduction. These subjects have ~cen extensively discussed during the meeting and several sections of this book are devoted to the presentation of the new data.

Contenu
Preface.- Section 1: Protochlorophyllide Photooxidoreductase Properties and Localisation.- A critical appraisal of the role and regulation of NADPH-protochlorophyllide oxidoreductase in greening plants.- Changes in the properties of protochlorophyllide reductase during early greening of etiolated squash cotyledons.- Proteolytic effects on the protochlorophyllide-oxidoreductase in oat.- Characterization of PChlide-protein complexes in PT and PLB enriched fractions of bean etioplasts. Effects of NADPH.- Protochlorophyll (ide) and chlorophyll (ide) in isolated original and reformed prolamellar bodies.- Section 2: Intermediates in Protochlorophyllide Photo-Reduction.- The long-wavelength-absorbing quenchers formed during illumination of protochlorophyllide-proteins.- Early processes of protochlorophyllide photoreduction as measured by nanosecond and picosecond spectrophotometry.- The primary reaction in the photoreduction of protochlorophyllide. A nanosecond fluorescence study.- Section 3: Protochlorophyllide and Chlorophyllide forms.- Protochlorophyllide and chlorophyllide-protein complexes during greening.- Fluorescence emission spectra of etiolated leaves measured at 296 and 77K during the first seconds of continuous illumination.- The regulatory effect of the cysteine/cystine redox couple on protochlorophyllide photoreduction in etioplasts.- The influence of the NADPH/NADP+ redox couple on the photoreduction of protochlorophyllide and on the spectral characteristics of the chlorophyllide-proteins in etioplasts.- The photoreduction of Zinc-protochlorophyllide by isolated etioplast lamellae.- A model for the reduction of protochlorophyll (ide) containing three different forms of photoactive protochlorophyll (ide).- Section 4: The First Photoactivities Apart from Protochlorophyllide Photoreduction.- The Franck-Inoue chlorophyllide micro-cycle II in vivo and in vitro.- Extension of the experiment by J.H.C. Smith on the onset of the oxygen evolution in etiolated bean leaves.- Thermoluminescence in etiolated bean leaves.- Section 5: Membrane Development and Pigment Composition.- Biosynthesis of the pigment-protein complexes.- Low temperature fluorescence spectra of Phaseolus vulgaris plastids durinq development in periodic or continuous light in the presence of the internal fluorescence standard Phycocyanin.- The composition of stroma and grana thylakoid pigment-protein complexes.- Effect of light and protein crosslinkers on the ultrastructure of isolated etioplast membranes.- Section 6: Energy Migration.- The energy migration in pigment assembly in relation to the chlorophyll biosynthesis.- The bioenergetic description of light energy migration in photoactive membranes; equivalence between the theory of the energy fluxes and the theory of the proportion of pigment forms to total pigments.- The dynamics of the photoreduction of protochlorophyll (ide) into chlorophyll (ide).- Section 7: Models.- Photochemical reduction of protochlorophyllide in detergent micelles with the final chlorophyllide formation.- Molecular structure of protochlorophyll forms.- Section 8: Special Topics.- Dark synthesis of chlorophyll in vivo and dark reduction of protochlorophyllide in vitro by pea chloroplasts.- Effect of leaf age on protochlorophyllide and chlorophyllide formation (a review).- Author index.