Protochlorophyllide: A photo-active pigment localized in prolamellar bodies occurring within the proplastids of dark-grown bean leaves. In the process of photoconversion, the highly fluorescent protochlorophyllide is converted to chlorophyll.Oxidoreductases Acting on CH-CH Group Donors: A subclass of enzymes which includes all dehydrogenases acting on carbon-carbon bonds. This enzyme group includes all the enzymes that introduce double bonds into substrates by direct dehydrogenation of carbon-carbon single bonds.Chlorophyllides: Products of the hydrolysis of chlorophylls in which the phytic acid side chain has been removed and the carboxylic acids saponified.Chlorophyll: Porphyrin derivatives containing magnesium that act to convert light energy in photosynthetic organisms.Oxidoreductases: The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)Rhodobacter capsulatus: Non-pathogenic ovoid to rod-shaped bacteria that are widely distributed and found in fresh water as well as marine and hypersaline habitats.Hordeum: A plant genus of the family POACEAE. The EDIBLE GRAIN, barley, is widely used as food.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Prochlorococcus: A genus of marine planktonic CYANOBACTERIA in the order PROCHLOROPHYTES. They lack PHYCOBILISOMES and contain divinyl CHLOROPHYLL, a and b.Chloroplasts: Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.Bacteriochlorophylls: Pyrrole containing pigments found in photosynthetic bacteria.Plastids: Self-replicating cytoplasmic organelles of plant and algal cells that contain pigments and may synthesize and accumulate various substances. PLASTID GENOMES are used in phylogenetic studies.Darkness: The absence of light.PhotochemistryAvena sativa: A plant species of the family POACEAE that is widely cultivated for its edible seeds.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Dithionite: Dithionite. The dithionous acid ion and its salts.Tetrapyrroles: Four PYRROLES joined by one-carbon units linking position 2 of one to position 5 of the next. The conjugated bond system results in PIGMENTATION.Cyanobacteria: A phylum of oxygenic photosynthetic bacteria comprised of unicellular to multicellular bacteria possessing CHLOROPHYLL a and carrying out oxygenic PHOTOSYNTHESIS. Cyanobacteria are the only known organisms capable of fixing both CARBON DIOXIDE (in the presence of light) and NITROGEN. Cell morphology can include nitrogen-fixing heterocysts and/or resting cells called akinetes. Formerly called blue-green algae, cyanobacteria were traditionally treated as ALGAE.Reducing Agents: Materials that add an electron to an element or compound, that is, decrease the positiveness of its valence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Chlorobium: A genus of phototrophic, obligately anaerobic bacteria in the family Chlorobiaceae. They are found in hydrogen sulfide-containing mud and water environments.Nitrogenase: An enzyme system that catalyzes the fixing of nitrogen in soil bacteria and blue-green algae (CYANOBACTERIA). EC 1.18.6.1.Aminolevulinic Acid: A compound produced from succinyl-CoA and GLYCINE as an intermediate in heme synthesis. It is used as a PHOTOCHEMOTHERAPY for actinic KERATOSIS.Thuja: A plant genus of the family CUPRESSACEAE.Levulinic Acids: Keto acids that are derivatives of 4-oxopentanoic acids (levulinic acid).NADP: Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)Protoporphyrins: Porphyrins with four methyl, two vinyl, and two propionic acid side chains attached to the pyrrole rings. Protoporphyrin IX occurs in hemoglobin, myoglobin, and most of the cytochromes.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Phytochrome: A blue-green biliprotein widely distributed in the plant kingdom.Triticum: A plant genus of the family POACEAE that is the source of EDIBLE GRAIN. A hybrid with rye (SECALE CEREALE) is called TRITICALE. The seed is ground into FLOUR and used to make BREAD, and is the source of WHEAT GERM AGGLUTININS.Seedling: Very young plant after GERMINATION of SEEDS.Porphyrins: A group of compounds containing the porphin structure, four pyrrole rings connected by methine bridges in a cyclic configuration to which a variety of side chains are attached. The nature of the side chain is indicated by a prefix, as uroporphyrin, hematoporphyrin, etc. The porphyrins, in combination with iron, form the heme component in biologically significant compounds such as hemoglobin and myoglobin.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Singlet Oxygen: An excited state of molecular oxygen generated photochemically or chemically. Singlet oxygen reacts with a variety of biological molecules such as NUCLEIC ACIDS; PROTEINS; and LIPIDS; causing oxidative damages.Cereals: Seeds from grasses (POACEAE) which are important in the diet.Spectrophotometry: The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.Spectrum Analysis: The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Peas: A variable annual leguminous vine (Pisum sativum) that is cultivated for its rounded smooth or wrinkled edible protein-rich seeds, the seed of the pea, and the immature pods with their included seeds. (From Webster's New Collegiate Dictionary, 1973)