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1.
Bodil Kjær Yean-Sung Jung Lian Yu John H. Golbeck Henrik Vibe Scheller 《Photosynthesis research》1994,41(1):105-114
The photosynthetic reaction center complex from the green sulfur bacteriumChlorobium vibrioforme has been isolated under anaerobic conditions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals polypeptides with apparent molecular masses of 80, 40, 30, 18, 15, and 9 kDa. The 80- and 18-kDa polypeptides are identified as the reaction center polypeptide and the secondary donor cytochromec
551 encoded by thepscA andpscC genes, respectively. N-terminal amino acid sequences identify the 40-kDa polypeptide as the bacteriochlorophylla-protein of the baseplate (the Fenna-Matthews-Olson protein) and the 30-kDa polypeptide as the putative 2[4Fe-4S] protein encoded bypscB. Electron paramagnetic resonance (EPR) analysis shows the presence of an iron-sulfur cluster which is irreversibly photoreduced at 9K. Photoaccumulation at higher temperature shows the presence of an additional photoreduced cluster. The EPR spectra of the two iron-sulfur clusters resemble those of FA and FB of Photosystem I, but also show significantly differentg-values, lineshapes, and temperature and power dependencies. We suggest that the two centers are designated Center I (with calculatedg-values of 2.085, 1.898, 1.841), and Center II (with calculatedg-values of 2.083, 1.941, 1.878). The data suggest that Centers I and II are bound to thepscB polypeptide. 相似文献
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Thea Kristiansen Jens‐Christian Svenning Wolf L. Eiserhardt Dennis Pedersen Hans Brix Søren Munch Kristiansen Maria Knadel César Grández Henrik Balslev 《Journal of Biogeography》2012,39(7):1318-1332
Aim It is a central issue in ecology and biogeography to understand what governs community assembly and the maintenance of biodiversity in tropical rain forest ecosystems. A key question is the relative importance of environmental species sorting (niche assembly) and dispersal limitation (dispersal assembly), which we investigate using a large dataset from diverse palm communities. Location Lowland rain forest, western Amazon River Basin, Peru. Methods We inventoried palm communities, registering all palm individuals and recording environmental conditions in 149 transects of 5 m × 500 m. We used ordination, Mantel tests and indicator species analysis (ISA) to assess compositional patterns, species responses to geographical location and environmental factors. Mantel tests were used to assess the relative importance of geographical distance (as a proxy for dispersal limitation) and environmental differences as possible drivers of dissimilarity in palm species composition. We repeated the Mantel tests for subsets of species that differ in traits of likely importance for habitat specialization and dispersal (height and range size). Results We found a strong relationship between compositional dissimilarity and environmental distance and a weaker but also significant relationship between compositional dissimilarity and geographical distance. Consistent with expectations, relationships with environmental and geographical distance were stronger for understorey species than for canopy species. Geographical distance had a higher correlation with compositional dissimilarity for small‐ranged species compared with large‐ranged species, whereas the opposite was true for environmental distance. The main environmental correlates were inundation and soil nutrient levels. Main conclusions The assembly of palm communities in the western Amazon appears to be driven primarily by species sorting according to hydrology and soil, but with dispersal limitation also playing an important role. The importance of environmental characteristics and geographical distance varies depending on plant height and geographical range size in agreement with functional predictions, increasing our confidence in the inferred assembly mechanisms. 相似文献
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The occurrence of bikunin and ·1-microglobuli n was investigated in human ovary and Fallopian tubes. Bikunin and ·1-microglobulin are transcribed in the liver from a common gene. Bikunin immunoreactivity was detected in the zona pellucida.
A positive reaction for bikunin was also observed in connective tissue of the oviduct. In addition, mast cells showed a more
intense posi tive reaction than the surrounding connective tissue. Specific displaceable ·1-microglobulin immunoreactivity was revealed in the zona pellucida. The data suggest that bikunin and ·1- microglobulin are trapped in the zona pellucida.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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Susanne Berglund Bryan J. Egner Henrik Gradén Joakim Gradén David G.A. Morgan Tord Inghardt Fabrizio Giordanetto 《Bioorganic & medicinal chemistry letters》2009,19(15):4268-4273
Herein, we disclose the discovery and optimization of 2-piperidin-4-yl-acetamide derivatives as MCH-R1 antagonists. Structural investigation of piperidin-4-yl-amide and piperidin-4-yl-ureas identified 2-piperidin-4-yl-acetamide-based MCH-R1 antagonists with outstanding in vivo efficacy but flawed with high affinity towards the hERG potassium channel. While existing hERG SAR information was employed to discover highly potent MCH-R1 antagonists with minimized hERG inhibition, additional hurdles prevented their subsequent clinical exploration. 相似文献
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Location of a dicyclohexylcarbodiimide-reactive glutamate residue in the Neurospora crassa plasma membrane H+-ATPase 总被引:3,自引:0,他引:3
M R Sussman J E Strickler K M Hager C W Slayman 《The Journal of biological chemistry》1987,262(10):4569-4573
The proton pump (H+-ATPase) found in the plasma membrane of the fungus Neurospora crassa is inactivated by dicyclohexylcarbodiimide (DCCD). Kinetic and labeling experiments have suggested that inactivation at 0 degrees C results from the covalent attachment of DCCD to a single site in the Mr = 100,000 catalytic subunit (Sussman, M. R., and Slayman, C. W. (1983) J. Biol. Chem. 258, 1839-1843). In the present study, when [14C]DCCD-labeled enzyme was treated with the cleavage reagent, N-bromosuccinimide, a single major radioactive peptide fragment migrating at about Mr = 5,300 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was produced. The fragment was coupled to glass beads and partially sequenced by automated solid-phase Edman degradation at the amino terminus and at an internal tryptic cleavage site. By comparison to the DNA-derived amino acid sequence for the entire Mr = 100,000 polypeptide (Hager, K., and Slayman, C. W. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7693-7697), the fragment has been identified as arising by cleavage at tyrosine 100 and tryptophan 141. Covalently incorporated [14C]DCCD was released at a position corresponding to glutamate 129. The DCCD-reactive glutamate is located in the middle of the first of eight predicted transmembrane sequences. When the sequence surrounding the DCCD site is compared to that surrounding the DCCD-reactive residue of two other proton pumps, the F0F1-ATPase and cytochrome c oxidase, no homology is apparent apart from an abundance of hydrophobic amino acids. 相似文献
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Dennis R. Roop Henrik Huitfeldt Anne Kilkenny Stuart H. Yuspa 《Differentiation; research in biological diversity》1987,35(2):143-150
Monospecific antibodies to mouse epidermal keratins were generated in rabbits and guinea pigs by injecting synthetic peptides of unique keratin sequences. The sequences were deduced from nucleotide sequences of cDNA clones representing basal (K14) and suprabasal (K1 and K10) cell-specific and hyperproliferative (K6) keratins of both the type-I and type-II subclasses. By applying single-and double-label immunofluorescence analysis, the expression of keratin peptides was analyzed in cultured keratinocytes maintained in the basal or suprabasal cell phenotypes. These cell types were selected by growth in medium containing 0.05 mM Ca2+ (basal cell) or 1.4 mM Ca2+ (suprabasal cell). The cultured basal cells expressed K6 and K14, but less than 1% expressed K1 and K10. Within a few hours after being placed in 1.4 mM Ca2+, K1 expression was observed, and by 24 h, 10%-17% of the cells expressed K1. K10 expression appeared to lag behind K1 expression, with only 5%-10% of cells in 1.4 mM Ca2+ exhibiting K10 immunoreactivity. Double-labeling studies indicated that virtually all K10-positive cells also expressed K1, while only about one-half of the K1-positive cells expressed K10. The treatment of basal cells with retinoic acid at pharmacological concentrations prevented the expression of K1 and K10 when cells were challenged by 1.4 mM Ca2+. Similarly, the introduction of the v-rasH oncogene into basal cells by a defective retroviral vector prevented the expression of suprabasal keratins in 1.4 mM Ca2+ medium.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献