Search results for "Cyclic compound"
showing 10 items of 819 documents
Recombinant water-soluble chlorophyll protein from Brassica oleracea var. Botrys binds various chlorophyll derivatives.
2003
A gene coding for water-soluble chlorophyll-binding protein (WSCP) from Brassica oleracea var. Botrys has been used to express the protein, extended by a hexahistidyl tag, in Escherichia coli. The protein has been refolded in vitro to study its pigment binding behavior. Recombinant WSCP was found to bind two chlorophylls (Chls) per tetrameric protein complex but no carotenoids in accordance with previous observations with the native protein [Satoh, H., Nakayama, K., Okada, M. (1998) J. Biol. Chem. 273, 30568-30575]. WSCP binds Chl a, Chl b, bacteriochlorophyll a, and the Zn derivative of Chl a but not pheophytin a, indicating that the central metal ion in Chl is essential for binding. WSCP …
The Existence of Chlorophyll c in the Chl b‐Containing, Light‐Harvesting Complex of the Green Alga Mantoniella squamata (Prasinophyceae)
1988
The prasinophycean alga Mantoniella contains, in addition to Chl a and b, at least a third green pigment which is functionally active in the light-harvesting antenna. This third Chl was isolated in order to elucidate its chemical structure. The absorption and fluorescence spectra were measured not only from the purified pigment but also from its pheophytin and its methylpheophorbide. The spectra were compared with those of authentic Chl c-1 and c-2, which were isolated from the diatom Nitzschia sp. and with Mg-DVPP (purified from Rhodobacter). The results show that the pigment from Mantoniella compares best with Chl c-1. In order to clarify the spectral data, Chl c-1 and c-2, Mg-DVPP, and t…
Epoxidation of benzo[a]pyrene-7,8-dihydrodiol by human CYP1A1 in reconstituted membranes. Effects of charge and nonbilayer phase propensity of the me…
2002
Human cytochrome P4501A1 (CYP1A1) is one of the key enzymes in the bioactivation of environmental pollutants such as benzo[a]pyrene (B[a]P) and other polycyclic aromatic hydrocarbons. To evaluate the effect of membrane properties and distinct phospholipids on the activity of human CYP1A1 purified insect cell-expressed human CYP1A1 and of human NADPH-P450 reductase were reconstituted into phospholipid vesicle membranes. Conversion rates of up to 36 pmol x min(-1) x pmol(-1) CYP1A1 of the enantiomeric promutagens (-)- and (+)-trans-7,8-dihydroxy-7,8-dihydro-B[a]P (7,8-diol) to the genotoxic diolepoxides were achieved. The highest rates were obtained when negatively charged lipids such as phos…
Contribution of Cholesterol and Oxysterols in the Physiopathology of Cataract: Implication for the Development of Pharmacological Treatments
2010
The development of cataract is associated with some lipid changes in human lens fibers, especially with increased accumulation and redistribution of cholesterol inside these cells. Some direct and indirect lines of evidence, also suggest an involvement of cholesterol oxide derivatives (also named oxysterols) in the development of cataract. Oxysterol formation can result either from nonenzymatic or enzymatic processes, and some oxysterols can induce a wide range of cytotoxic effects (overproduction of reactive oxygen species (ROS); phospholipidosis) which might contribute to the initiation and progression of cataract. Thus, the conception of molecules capable of regulating cholesterol homeos…
A quantitative method of photoadsorption determination for irradiated catalyst in liquid–solid system
2009
WOS: 000266963000002
Enhanced electron-transfer properties of cofacial porphyrin dimers through pi-pi interactions
2009
pi-pi assisted: Photoinduced electron transfer from cofacial porphyrin dimers to electron acceptors is prominently accelerated, whereas the back electron transfer is decelerated, relative to the corresponding porphyrin monomer (see figure).The radical cation of zinc tetrapentylporphyrin is dimerized with an excess of the neutral counterpart to form the dimer radical cation in which the unpaired electron is delocalized over both porphyrin rings. The dimeric radical cation exhibits an NIR absorption spectrum characteristic of weak pi-bond formation between the porphyrin rings. When cofacial porphyrin dimers, linked by different spacers, are oxidized such pi-bond formation between the porphyri…
Thylakoid Membrane Maturation and PSII Activation Are Linked in Greening Synechocystis sp. PCC 6803 Cells
2013
Abstract Thylakoid membranes are typical and essential features of both chloroplasts and cyanobacteria. While they are crucial for phototrophic growth of cyanobacterial cells, biogenesis of thylakoid membranes is not well understood yet. Dark-grown Synechocystis sp. PCC 6803 cells contain only rudimentary thylakoid membranes but still a relatively high amount of phycobilisomes, inactive photosystem II and active photosystem I centers. After shifting dark-grown Synechocystis sp. PCC 6803 cells into the light, “greening” of Synechocystis sp. PCC 6803 cells, i.e. thylakoid membrane formation and recovery of photosynthetic electron transport reactions, was monitored. Complete restoration of a t…
Chloroplast DNA evidence for introgression and long distance dispersal in the desert annualSenecio flavus (Asteraceae)
1995
Phylogenetic analysis of chloroplast DNA (cpDNA) restriction site variation supports a close genetic relationship between the Southwest AsianSenecio flavus subsp.breviflorus and the North AmericanS. mohavensis. The intercontinental disjunct distribution of these two desert annuals may have originated via long distance dispersal. The chloroplast genomes of the Southern and North AfricanS. flavus subsp.flavus and subsp.breviflorus differ by at least ten restriction sites, while at most two restriction sites differentiate the cpDNA genomes of subsp.breviflorus and the outgroupS. squalidus. This suggests that the cpDNA genome ofS. flavus subsp.breviflorus may have resulted from introgression an…
The fungal elicitor cryptogein is a sterol carrier protein
1997
AbstractCryptogein is a protein secreted by the phytopathogenic pseudo-fungus, Phytophthora cryptogea. It is a basic 10 kDa hydrophilic protein having a hydrophobic pocket and three disulfide bridges. These common features with sterol carrier proteins led us to investigate its possible sterol transfer activity using the fluorescent sterol, dehydroergosterol. The results show that cryptogein has one binding site with strong affinity for dehydroergosterol. Moreover, this protein catalyzes the transfer of sterols between phospholipidic artificial membranes. This is the first evidence for the existence of an extracellular sterol carrier protein and for a molecular activity of cryptogein. This p…
Gas—liquid chromatographic analyses
1989
Abstract The retention (I), dispersion (IM) and selectivity (I*) indices of sixteen polychlorinated dibenzo-p-dioxins and fourteen polychlorinated dibenzofurans were determined on a low-polarity HP-5 capillary column using a gas chromatograph connected with an ion-selective detector. IM and I* values were also calculated for all 73 dibenzo-p-dioxins from the di- to the octachloro isomer and for all possible 135 chlorinated dibenzofurans based on the predicted retention index data reported earlier. The effect of the position of chlorination is shown and the results are compared with those for several series of chlorinated aromatics.