Porphyrin Derivatives
Mostrando 13-21 de 21 artigos, teses e dissertações.
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13. Sequence-targeted chemical modifications of nucleic acids by complementary oligonucleotides covalently linked to porphyrins.
Oligo-heptathymidylates covalently linked to porphyrins bind to complementary sequences and can induce local damages on the target molecule. In dark reactions, iron porphyrin derivatives exhibited various chemical reactivities resulting in base oxidation, crosslinking and chain scission reactions. Reactions induced by reductants, such as ascorbic acid, dithi
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14. Rotational barrier of a molybdenum-molybdenum quadruple bond
The synthesis and characterization of molybdenum(II) porphyrin dimers containing unbridged metal-metal quadruple bonds are presented. Variable temperature 300 MHz 1H NMR studies of meso-substituted derivatives provide novel solution evidence for both the existence of quadruple bonds and for a barrier to rotation about the metal-metal bonds in these complexes
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15. Arabidopsis alternative oxidase sustains Escherichia coli respiration.
Glutamyl-tRNA reductase, encoded by the hemA gene, is the first enzyme in porphyrin biosynthesis in many organisms. Hemes, important porphyrin derivatives, are essential components of redox enzymes, such as cytochromes. Thus a hemA Escherichia coli strain (SASX41B) is deficient in cytochrome-mediated aerobic respiration. Upon complementation of this strain w
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16. Metabolism of δ-Aminolevulinic Acid in Red and Blue-Green Algae 1
δ-Aminolevulinic acid was incorporated in vivo into C-phycocyanin and B-phycoerythrin in two species of the Rhodophyta (Cyanidium caldarium, Porphyridium cruentum) and three species of the Cyanophyta (Anacystis nidulans, Plectonema boryanum, Phormidium luridum). Amino acid analysis of phycocyanin-14C from C. caldarium cells which had been incubated with δ-
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17. Binding Specificity of the Porphyromonas gingivalis Heme and Hemoglobin Receptor HmuR, Gingipain K, and Gingipain R1 for Heme, Porphyrins, and Metalloporphyrins
Previous genetic and biochemical studies have confirmed that hemoglobin and hemin utilization in Porphyromonas gingivalis is mediated by the outer membrane hemoglobin and heme receptor HmuR, as well as gingipain K (Kgp), a lysine-specific cysteine protease, and gingipain R1 (HRgpA), one of two arginine-specific cysteine proteases. In this study we report on
American Society for Microbiology.
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18. Peroxynitrite decomposition catalysts: Therapeutics for peroxynitrite-mediated pathology
Inflamed tissue is often characterized by the production of NO and superoxide. These radicals react at diffusion-limited rates to form the powerful oxidant peroxynitrite (PN). When protonated, PN decomposes into either nitrate or reactive intermediates capable of mediating tissue damage by oxidation of protein, lipid, and nucleic acid. We recently have ident
The National Academy of Sciences.
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19. "Tension" on heme by the proximal base and ligand reactivity: conclusions drawn from model compounds for the reaction of hemoglobin.
The kinetic data on model compounds of hemoglobin indicate that in oxyderivatives ligand dissociation rates are sensitive to the "tension" exerted by the proximal base on the metal-to-ligand bond; the corresponding rates for carboxy derivatives are not sensitive to the tension. It is suggested that the metal-to-ligand bond becomes weaker with increased "pull
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20. Mechanism of DNA cleavage by cationic manganese porphyrins: hydroxylations at the 1'-carbon and 5'-carbon atoms of deoxyriboses as initial damages.
Cationic manganese-porphyrin complexes, free or targetted with an intercalating agent, are able to cleave DNA using oxygen atom donors like potassium monopersulfate or magnesium monoperphthalate as coreactants. Detailed studies of the cleavage of calf thymus DNA, before and after a heating step, show that free bases and 5-methylene-2-furanone are the main re
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21. Specific inhibition of antenna bacteriochlorophyll synthesis in Chlorobium vibrioforme by anesthetic gases.
The green sulfur bacterium Chlorobium vibrioforme contains two types of bacteriochlorophyll (Bchl). The minor pigment, Bchl a, is associated primarily with the cell membrane and its reaction centers; and the major light-harvesting antenna pigment, Bchl d, is found primarily in the chlorosomes, which are attached to the inner surface of the cell membrane. Ane