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Replacement of bacteriopheophytin in reaction centers from Rhodobacter sphaeroides RS601 with plant pheophytin

Science China(Life Sciences) 2000年第1期43卷 21-29页

作者：曾小华吴永强沈允钢徐春和 Shanghai Institute of Plant Physiology Chinese Academy of Sciences Shanghai 200032 China

In the presence of acetone and an excess of exogenous plant pheophytins, bacterio-pheophytins in the reaction centers from Rhodobacter sphaeroides RS601 were replaced by pheophytins at sites HA and HB, when incubated at 43.5℃ for more than 15 min. The substitution of bacteriopheophytins in the reaction centers was 50% and 71% with incubation of 15 and 60 min, respectively. In the absorption spectra of pheophytin-replaced reaction centers (Phe RCs), bands assigned to the transition moments Qx (537 nm) and QY (758 nm) of bacteriopheophytin disappeared, and three distinct bands assigned to the transition moments Qx (509/542 nm) and QY (674 nm) of pheophytin appeared instead. Compared to that of the control reaction centers, the photochemical activities of Phe RCs are 78% and 71% of control, with the incubation time of 15 and 60 min. Differences might exist between the redox properties of Phe RC and of native reaction centers, but the substitution is significant, and the new system is available for further studies.

关键词： bacterial-photosynthetic reaction center pheophytin pigment replacement activity of light-induced electron transfer.

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ENERGY TRANSFER BETWEEN CHLOROPHYLL AND pheophytin

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Chinese Science Bulletin 1988年第14期33卷 1215-1218页

作者：杨善元 Shanghai Institute of Plant Physiology Academia Stnica

Although it is well known that there are two photosystems catalyzing different photochemical reactions in the chloroplast thylakoid membrane of higher plants, yet the components of these systems are not so clear. In 1977, Klimov, according to the light-dark differential spectrum of photosystem Ⅱ particles and the kinetic behavior of absorption and of fluorescence intensity change at 685 nm, concluded that pheo- phytin (Pheo) was the primary electron acceptor of photosystem Ⅱ. This report attracts much interest of workers to search the evidence of pheophytin as primary elec- tron acceptor in photosynthetic process.

关键词： chlorophyll pheophytin delayed light emission enery transfer

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The Antioxidant and Free Radical Scavenging Activities of Chlorophylls and pheophytins

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Food and Nutrition Sciences 2013年第8期4卷 1-8页

作者： Ching-Yun Hsu Pi-Yu Chao Shene-Pin Hu Chi-Ming Yang Biodiversity Research Center Academia Sinica Taipei Taiwan Department of Food and Nutrition Chinese Culture University Taipei Taiwan Department of Nutrition and Health Sciences Chang Gung University of Science and Technology Taoyuan Taiwan School of Nutrition and Health Science Taipei Medical University Taipei Taiwan

Chlorophylls are important antioxidants found in foods. We explored the mechanisms through which the a and b forms of chlorophyll and of pheophytin (the Mg-chelated form of chlorophyll) reduce oxidation: we used comet assay to measure prevention of H2O2 DNA damage;we tested for quenching of 1,1-diphenyl-2-picrylhydrazyl (DPPH);we measured the ability to chelate Fe(II);and, we tested their ability to prevent formation of thiobarbituric acid reactive substances (TBARS) during Cu-mediated peroxidation of low density lipoprotein (LDL) in a chemical assay. All chlorophylls and pheophytins showed significant dose-dependent activity in the assays, with the pheophytins being the strongest antioxidants. Thus, these chemicals can prevent oxidative DNA damage and lipid peroxidation both by reducing reactive oxygen species, such as DPPH, and by chelation of metal ions, such as Fe(II), which can form reactive oxygen species.

关键词： Chlorophyll pheophytin Comet Assay Antioxidation

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