Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cytochrome-enriched fraction obtained from chloroplasts after treatment with the detergent digitonin contained cytochromes f, b-559LP and b-563 in the approximate proportions 1:1:2, close to those observed in unfractionated chloroplasts. The spectrum of cytochrome b-563 at temperature of liquid N2 showed a single asymmetrical alpha-band with a maximum at 561 nm.
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PMID:Composition and spectral properties of a cytochrome-enriched fraction obtained from chloroplasts by digitonin treatment. 50 3

A photosystem II complex containing the reaction center proteins D1 and D2, a 47-kDa chlorophyll-binding protein (CP47), and cytochrome b-559 was isolated with high yield, purity, and homogeneity; small but well-ordered two-dimensional crystals were prepared from the particles. The crystals and the isolated particles were analyzed by electron microscopy using negatively stained specimens. The information of 20 different digitized crystals was combined by alignment programs based on correlation methods to obtain a final average. The calculated diffraction pattern, with spots up to a resolution of 2.5 nm, and the optical diffraction pattern of a single crystal indicate that the plane group is p22121 (also called p2gg) and that the unit cell is rectangular with parameters of 23.5 x 16.0 nm, containing four stain-excluding monomers (two face-up and two face-down). In projection, the monomers have an asymmetrical shape with a length of 10 nm, a maximal width of 7.5 nm, and a height of 6 nm; their molecular mass is 175 +/- 40 kDa.
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PMID:Characterization by electron microscopy of isolated particles and two-dimensional crystals of the CP47-D1-D2-cytochrome b-559 complex of photosystem II. 218 33

Bacillus subtilis cytoplasmic membranes contain several cytochromes which are linked to the respiratory chain. At least six different cytochromes have been separated and identified by ammonium sulphate fractionation and ion-exchange chromatography. They include two terminal oxidases with CO-binding properties and cyanide sensitivity. One of these is an aa3-type cytochrome c oxidase which has characteristic absorption maxima in the reduced-oxidized difference spectrum at 601 nm in the alpha-band and at 443 nm in the Soret band regions. In the alpha-band two separate electron transitions with Em = +205 mV and Em = +335 mV can be discriminated by redox potentiometric titration. The other CO-binding cytochrome c oxidase contains two cytochrome b components with alpha-band maxima at 556 nm and 559 nm. Cytochrome b556 can be reduced by ascorbate and has an Em + +215 mV, whereas cytochrome b559 has an Em = +140 mV. Furthermore a complex consisting of a cytochrome b564 (Em = +140 mV) associated with a cytochrome c554 (Em = +250 mV) was found. This cytochrome c554, which can be reduced by ascorbate, appears to have an asymmetrical alpha-peak and stains for heme-catalyzed peroxidase activity on SDS-containing polyacrylamide gels. A protein with a molecular mass of about 30 kDa is responsible for this activity. A cytochrome b559 (Em = +65 mV) appears to be an essential part of succinate dehydrogenase. Finally a cytochrome c550 component with an apparent mid-point potential of Em = +195 mV has been detected.
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PMID:Spectral and potentiometric analysis of cytochromes from Bacillus subtilis. 311 50

bI1 RNA (excised from the first intron of the long form of the cytochrome b gene of Saccharomyces cerevisiae mitochondria) hybridizes with the two strands of a Bg/II-MboI DNA segment from this region. This fraction is resistant to digestions by DNase I and RNase T1 and disappears completely upon alkali hydrolysis. Strand-specific labeling of an intronic DNA fragment, cloned in pBR322 plasmid, was accomplished through the use of a T4 DNA polymerase. The purity of the probes was demonstrated by cloning an exon-intron fragment and labeling it by the same procedure; mRNA and pre-mRNA bands hybridized only with the transcribed DNA strand whereas bI1 RNA hybridized with the two strands under the stringent washing conditions employed (tm + 20 degrees C). Several experimental results argue against the possibility that the observation of two complementary bI1 RNA strands results from a partial self-complementarity of the RNA. A pre-mRNA intermediate from a box8 (G5046) mutant, still containing this intron, hybridizes only with the transcribed DNA strand of the pure intronic probe. The amount of the non-sense bI1 RNA strand is very low, in cells from two wild-type strains, relative to the sense RNA strand during the early stages of growth on glucose. It increases as the cells are released from glucose repression. bI1 RNA is resistant to RNase. Very little self-complementarity is seen by computer analysis of the sequence. Purified bI1 RNA is seen by electron microscopy under non-denaturing conditions as a mixture of double-stranded circular and linear molecules thus confirming the existence of the two complementary strands. The disappearance of all material following alkali hydrolysis demonstrates that these are indeed two RNA strands. Under fully denaturing conditions a mixture of single-stranded circular and linear molecules is seen as reported previously (Cell, 19, 321-329, 1980). We conclude that yeast mitochondria contain the two complementary bI1 RNA strands, one circular and the other linear. Considering a largely asymmetrical transcription of the mitochondrial genome in yeast and assuming that circularization of some intronic RNAs is part of RNA processing, we do not believe that the two strands are each a mixture of linear and circular molecules. The ratio of non-sense to sense bI1 RNA in a cytoplasmic petite mutant, A1B1, also varies according to growth conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Yeast mitochondria contain a linear RNA strand complementary to the circular intronic bI1 RNA of cytochrome b. 620 24

The structure and molecular interactions of the primary donor (P680) in the reaction center (D1-D2-cytochrome b-559 complex) of photosystem II (PS II) have been investigated by detecting light-induced FT-IR difference spectra upon the formation of its triplet state (3P680). The 3P680/P680 spectrum obtained was analyzed by comparing it with difference spectra between the ground and lowest triplet states of purified chlorophyll a (Chl) in organic solvents. The negative peaks at 1669 and 1707 cm-1 accompanied by the positive peaks at 1627 and 1659 cm-1 in the 3P680/P680 spectrum were assigned to the keto C = O stretching mode, and the appearance of these two pairs of bands indicated that P680 has a dimeric structure analogous to that of the bacterial primary donor. From the band positions of the keto and carbomethoxy C = O stretches, the hydrogen-bonding properties of these two Chl molecules were found to be asymmetrical; in one Chl molecule both the keto and carbomethoxy C = O groups form hydrogen bonds, while in the other Chl molecule the keto C = O is not hydrogen-bonded whereas the carbomethoxy C = O probably is hydrogen-bonded. The temperature dependence of the intensity ratios of the keto C = O bands revealed that the triplet state is equilibrated between the two Chl molecules with an energy gap of 8.4 +/- 0.7 meV. Most of the triplet population was found to be localized on one Chl molecule (86% at 80 K), in which both of the two C = O groups are hydrogen-bonded, that is probably attached to the D1 subunit. Considering the structure of the bacterial reaction center determined by X-ray crystallography and the sequence homology between the D1 and D2 subunits of PS II and the L and M subunits of bacteria, a model of the P680 structure and its interactions with apoproteins has been proposed.
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PMID:FT-IR studies on the triplet state of P680 in the photosystem II reaction center: triplet equilibrium within a chlorophyll dimer. 834 8

Two dimensional (2D) crystals of photosystem II (PSII) were obtained from n-heptyl-beta-D-thioglucoside-solubilized monomers of spinach PSII complex by conventional detergent dialysis. The 2D crystals were either large cylindrical vesicles (1 to 2 micrometer by 4 to 6 micrometer as flattened vesicles) or large monolayer sheets (ca. 1 micrometer X 1 micrometer), both suitable for cryo-electron microscopy. Images of unstained crystals embedded in ice were recorded using low-dose microscopy and analyzed by digital image processing. Both types of crystals had the same unit cell size and the same packing arrangement of PSII particles. The plane group was p22(1)2(1) and the unit cell was rectangular with dimensions of 16.7 nm X 15.3 nm containing four monomers (two face-up and two face-down). SDS-PAGE and immunoblot analyses of the 2D crystal indicated that the constituent subunits of particles in the 2D were CP47, D1, D2, cytochrome b-559 and psbI protein. A projection map of 20 A resolution revealed that each monomer has asymmetrical shape with a length of 8.1 nm and a maximal width of 7.5 nm consisting of four areas of density. Two high-density areas with similar sizes were located close to each other to form a roughly rectangular core of 4.0 nm X 6.5 nm. From its size similarity to the size of the L/M heterodimer of the bacterial reaction center, this high density core area was tentatively assigned to the D1/D2 heterodimer. The remaining large and small areas were also tentatively assigned to CP47 and cytochrome b-559 plus psbI protein respectively.
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PMID:Two-dimensional crystallization and cryo-electron microscopy of photosystem II. 860 19

By using single-strand conformation polymorphism (SSCP) analysis of three amplicons of the cytochrome b gene obtained by the polymerase chain reaction (PCR) it was possible to differentiate between various species of tunas and bonitos processed as canned fish. Four different techniques were used to produce single-strand DNA (ssDNA): (i) Denaturation of double-strand DNA (dsDNA) by formamide and alkali, (ii) two-step asymmetrical PCR, (iii) one-step asymmetrical PCR, and (iv) exonuclease digestion of the phosphorylated strand of dsDNA. The technique rendering optimal results depended on the type of amplicon (i.e. the sequence).
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PMID:Comparison of different methods to produce single-strand DNA for identification of canned tuna by single-strand conformation polymorphism analysis. 969 85

A cDNA clone for cytochrome b(5) was isolated from a cDNA library of an ascidian, Ciona savignyi, by a plaque hybridization method using a digoxigenin-labeled cDNA for the soluble form of human cytochrome b(5). The cDNA is composed of 5'- and 3'-noncoding sequences, and a 396-base pair coding sequence. The 3'-noncoding sequence contains polyadenylation signal sequences. The amino acid sequence of 132 residues deduced from the nucleotide sequence of the cDNA showed 61% identity and 82% similarity to the cytochrome b(5) of another ascidian species, Polyandrocarpa misakiensis, which we previously cloned. The amino-terminal hydrophilic domain of 98 residues contains well-conserved structures around two histidine residues for heme binding. A cDNA expression system was constructed to prepare a putative soluble form of Ciona cytochrome b(5). The recombinant soluble cytochrome b(5) showed an asymmetrical absorption spectrum at 560 nm as is shown by mammalian cytochromes b(5) upon reduction with NADH and NADH-cytochrome b(5) reductase. The recombinant Ciona cytochrome b(5) is reduced by NADH-cytochrome b(5) reductase with an apparent K(m) value of 3.3 microM. This value is similar to that of the cytochrome b(5) of Polyandrocarpa misakiensis. The expression of Ciona cytochrome b(5) mRNA during development was examined by an in situ hybridization method and ubiquitous expression in embryonic tissues was observed. The results indicate that cytochrome b(5) plays important roles in various metabolic processes during development.
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PMID:Structure of a cDNA for Ciona Cytochrome b(5) and the ubiquitous expression of mRNA in embryonic tissues. 1504 25

Research on contact zones has paid relatively little attention to host-parasite interactions, although these situations have important but different implications depending on whether one considers the host or the parasite's perspective. We investigated both the role of a host contact zone in parasite expansion and whether parasites could influence contact zone dynamics. We studied the diversity and the patterns of parasite exchange (genera Haemoproteus and Plasmodium) infecting two parapatric sibling passerines meeting at a moving contact zone in western Europe. We amplified and sequenced a fragment of the parasite cytochrome b gene. The expanding host harboured more diverse parasites, which might indicate a superior ability to face a diverse parasite fauna than the receding host. Prevalence was very high in both hosts, due to the frequent occurrence of two sister Haemoproteus lineages. Despite the recent movement of the contact zone, these two parasites fitted almost perfectly to the geographic range of their main host species. Yet, we found several cases of cross-species infection in sympatric areas and evidences of asymmetrical spreading of parasites from the expanding host towards the receding host. Altogether, our results suggest that the host contact zone mainly acts as a barrier to parasite expansion even if recurrent host shifts are observed. Besides, they also support the idea that parasite-mediated competition might contribute to the displacement of hosts' contact zones, thereby emphasizing the role of parasitism on the population dynamics of sympatric species.
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PMID:Diversity, distribution and exchange of blood parasites meeting at an avian moving contact zone. 1649

Because of their exceptionally long independent evolution, a range diminution of their Eocene relatives, and a remarkable subsequent diversification in Southeast Asia, tarsiers are of particular importance to evolutionary primatologists. Little is known, however, on the processes shaping the radiation of these small enigmatic primates-especially on the Indonesian island of Sulawesi, their center of endemism. Geological reconstructions and progress in applying DNA sequence information to divergence dating now provide us with the tools and background to comprehend tarsier dispersal. Here, we describe effects of plate-tectonic movements, Pleistocene sea level changes, and hybridization on the divergence of central Sulawesi tarsiers. We analyzed 12 microsatellites, the cytochrome b gene, the hypervariable region I of the mitochondrial control region, and the sex-determining region on the Y-chromosome from 144 specimens captured along a transect crossing a species boundary and a contact zone between 2 microplates. Based on these differentially inherited genetic markers, geographic information, and recordings of vocalizations, we demonstrate that the species boundary coincides with a tectonic suture. We estimate the most recent common ancestor of the 2 taxa to have lived 1.4 Mya, we describe asymmetrical introgressive hybridization, and we give evidence of unbiased dispersal in one species and male-biased dispersal in another species. This study exemplifies that the distribution of tarsier acoustic forms on Sulawesi is consistent with the allocation of genetic variability and that plate-tectonic and glacial events have left traceable marks in the biogeography of this island's unique fauna.
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PMID:Elucidating geological and biological processes underlying the diversification of Sulawesi tarsiers. 1945 46


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