Chlorophyll Biosynthesis And Technological Applications

Heme and chlorophyll (Chl) are porphyrins. Porphyrins (also referred to as tetrapyrroles) are essential for life in the biosphere. Chlorophyll catalyzes the conversion of solar energy to chemical energy via the process of photosynthesis. Organic life in the biosphere is made possible by consumption of the chemical energy generated by photosynthesis. Hemes are the prosthetic groups of cytochromes which are involved in electron transport during oxidative phosphorylation and photosynthetic phosphorylation which generate ATP and NADPH. The latter are essential for many cellular functions. Chlorophyll on the other hands catalyzes the process of photosynthesis. Indeed, life in the biosphere depends on the process of photosynthesis which converts light energy, carbon dioxide and water into the chemical energy, required for the formation of food and fiber. Photosynthetic efficiency is controlled by extrinsic factors such as the availability of water, CO2, inorganic nutrients, ambient temperature and the metabolic and developmental state of the plant, as well as by intrinsic factors (Lien and San Pietro, 1975). The most important intrinsic factor is the efficiency of the photosynthetic electron transport system (PETS). Conventional agriculture is one of the few human activities that have not undergone a revolution to join other activities such as overcoming gravity by flying, and landing on the moon, crossing underwater the polar cap, and communicating wirelessly over long distances via electromagnetic waves. We now feel that enough biochemical and molecular biological knowledge has accumulated to render this dream amenable to experimentation. We believe that the time has come to bioengineer chloroplasts capable of synthesizing a short chain carbohydrate such as glycerol at rates that approach the upper theoretical limits of photosynthesis [Rebeiz, C. A. (2010) Investigations of possible relationships between the chlorophyll biosynthetic pathway and the assembly of chlorophyll-protein complexes and photosynthetic efficiency. In: Rebeiz, C. A. Benning, C., Bohnert, H.J., Daniell, H., Hoober J. K., Lichtenthaler, H. K., Portis , A. R., and Tripathy, B. C. eds. The chloroplast: Basics and Applications. Springer. The Netherlands, p 1-24]. In order to achieve this goal a thorough knowledge of the Chl biosynthetic pathway is needed along with knowledge in other domains (Rebeiz 2010). In this context, this monograph is devoted to an in depth discussion of our present knowledge of the Chl biosynthetic pathway. The complexity and biochemical heterogeneity of the Chl biosynthetic pathway and the relationship of this complexity to the structural and biosynthetic complexity of photosynthetic membranes will be emphasized. We will also emphasize in historical perspective, key stages in our understanding of the Chl biosynthetic heterogeneity. The reader should keep in mind that a complex biosynthetic process is only fully understood when it becomes possible to reconstitute in vitro every step of the process. We are not yet at this stage of understanding of thylakoid membrane biogenesis. Considerable progress has been achieved however, in the understanding of numerous facets of the Chl biosynthetic pathway, namely (a) detection and identification of various major and minor metabolic intermediates (b) precursor-product relationships between various intermediates, (c) structure and regulation of many enzymes of the pathway, and (d) the relationship of the Chl biosynthetic heterogeneity to the structural and functional heterogeneity of thylakoid membranes. In addition topics related to the development of Analytical techniques, Cell-free systems, Herbicides, Insecticides, and Cancericides are also discussed.

The first dedicated new work since 1991, this book reviews recent progress and current studies in the chemistry, metabolism and spectroscopy of chlorophylls, bacteriochlorophylls and their protein complexes. Also discussed is progress on the applications of chlorophylls as photosensitizers in photodynamic therapy of cancerous tumours, and as molecular probes in biochemistry, medicine, plant physiology, ecology and geochemistry. Each section offers an introductory overview followed by concise, focused and fully-referenced chapters written by experts.

Chlorophyll is a green pigment found in almost all plants, algae and cyanobacteria, and is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light. In this book, the authors present current research in the study of the structure, production and medicinal uses of chlorophyll. Topics discussed include the impact of molecular organisation on UV-irradiation effects to chlorophyll stability and biomedical applications; chlorophyll biosynthesis; genomics and phenomics of chlorophyll associated traits in abiotic stress tolerance breeding; chlorophyll fluorescence emission spectra in photosynthetic organisms and traditional medicinal uses of chlorophyll.

Metabolism, Structure and Function of Plant Tetrapyrroles, Volume 91, the latest release in the Advances in Botanical Research series is a compilation of the current state-of-the-art on the topic. Chapters in this new release cover Tetrapyrrole Pigments of Photosynthetic Antennae and Reaction Centers of Higher Plants: Biochemistry, Biophysics, Functions, Molecular Mechanism of Antenna Regulation, Applications, Chlorophyll c: Synthesis, Occurrence, Light-Harvesting, Absorbance, Excitation Properties, Pigment Organization in Chlorophyll-Binding Proteins (FCP), Chlorophyll d and f: Synthesis, Occurrence, Light-harvesting, Absorbance, Excitation Properties, Pigment Organization in Chlorophyll-Binding Protein Complexes, Analysis of Chlorophyll, Precursors and Derivatives by New High-Performance Liquid Chromatography and Mass Spectrometry, and much more. Presents the latest release in the Advances in Botanical Research series Provides an Ideal resource for post-graduates and researchers in the plant sciences, including botany, plant biochemistry, plant pathology and plant physiology Contains contributions from internationally recognized authorities in their respective fields

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Mg-chelatase catalyzes the insertion of Mg2+ into protoporphyrin-IX (Proto) in the chlorophyll biosynthetic pathway. This is the first step unique to the chlorophyll pathway and is at the branchpoint between heme and chlorophyll biosynthesis. Previous work from our laboratory has shown that the enzyme from pea chloroplasts requires three distinct protein fractions (now known to contain the D, I and H subunits). The reaction requires ATP in two distinct steps: activation requiring two of the fractions (I and D) and metal ion insertion, requiring all three fractions. Work covered in this granting period includes the cloning and expression of the active form of one of the pea subunits and demonstration of the change in chromatographic behavior of the subunits upon activation with ATP.

Chloroplasts are vital for life as we know it. At the leaf cell level, it is common knowledge that a chloroplast interacts with its surroundings – but this knowledge is often limited to the benefits of oxygenic photosynthesis and that chloroplasts provide reduced carbon, nitrogen and sulphur. This book presents the intricate interplay between chloroplasts and their immediate and more distant environments. The topic is explored in chapters covering aspects of evolution, the chloroplast/cytoplasm barrier, transport, division, motility and bidirectional signalling. Taken together, the contributed chapters provide an exciting insight into the complexity of how chloroplast functions are related to cellular and plant-level functions. The recent rapid advances in the presented research areas, largely made possible by the development of molecular techniques and genetic screens of an increasing number of plant model systems, make this interaction a topical issue.

“Photosynthesis: Plastid Biology, Energy Conversion and Carbon Assimilation” was conceived as a comprehensive treatment touching on most of the processes important for photosynthesis. Most of the chapters provide a broad coverage that, it is hoped, will be accessible to advanced undergraduates, graduate students, and researchers looking to broaden their knowledge of photosynthesis. For biologists, biochemists, and biophysicists, this volume will provide quick background understanding for the breadth of issues in photosynthesis that are important in research and instructional settings. This volume will be of interest to advanced undergraduates in plant biology, and plant biochemistry and to graduate students and instructors wanting a single reference volume on the latest understanding of the critical components of photosynthesis.