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121.
Isolation of L8 and L8S8 forms of ribulose bisphosphate carboxylase/oxygenase from Chromatium vinosum 总被引:1,自引:0,他引:1
The enzyme ribulose bisphosphate carboxylase/oxygenase has been purified from Chromatium vinosum. When an extract is subjected to centrifugation at 35,000xg in the presence of polyethylene glycol (PEG)-6000 and the supernatant is treated with 50 mM Mg2+ and the precipitate is then fractionated by vertical centrifugation into a reoriented sucrose gradient followed by chromatography on diethylaminoethyl (DEAE)-Sephadex A50, the resultant enzyme contains large (L) and small (S) subunits. Alternatively, centrifugation of extracts at 175,000xg in the presence of PEG-6000 followed by fractionation with Mg2+, density gradient centrifugation, and chromatography on DEAE-Sephadex A50 yields an enzyme free of small subunits. The two forms have comparable carboxylase and oxygenase activities and have compositions and molecular weights corresponding to L8 and L8S8 enzymes. The amino acid compositions of L and S subunits are reported. The L8S8 enzyme from spinach cannot be similarly dissociated by centrifugation at 175,000xg in the presence of PEG-6000.Abbreviations DEAE
diethylaminoethyl
- EDTA
ethylenediamine-tetraacetate
- MOPS
3-(N-morpholino)propanesulfonic acid
- PEG
polyethylene glycol
- RuBisCO
d-ribulose 1,5-bisphosphate caboxylase/oxygenase
- RnBP
d-ribulose 1,5-bisphosphate
- SDS
sodium dodecyl sulfate
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
Dedicated to Professor G. Drews on occasion of his 60th birthday 相似文献
122.
Preliminary characterization of carbohydrate stores from chlorarachniophytes (Division: Chlorarachniophyta) 总被引:2,自引:0,他引:2
Chlorarachniophytes are amoeboid/flagellate eukaryotes that harbor reduced green algal endosymbionts. The carbohydrate stores of chlorarachniophyte algae have been investigated using methylation analysis to determine monosaccharide composition. An appreciable quantity of long chain β-1,3 glucan occurs in these algae. Immunogold electron microscopy using an antibody specific for (β-1,3 glucans localized (β-1,3 glucans within a vacuole in the host cell cytoplasm. The results suggest that photosynthate produced by the endosymbiont is stored by the host. Implications of the data for endosymbiosis are discussed. 相似文献
123.
Intact cells of Pseudomonas facilis contain one major molecular weight class of protein that is exposed at the cell surface as revealed by lactoperoxidase-catalyzed iodination with (125)I. All molecular weight classes of protein in derived cell envelope preparations are apparently saturated by iodination by lactoperoxidase after prolonged sonic treatment. The molecular weight of the predominantly exposed protein in intact cells is approximately 16,000, which is the minimal molecular weight of a cell envelope protein that precipitates as a complex with phospholipid from extracts of P. facilis. The isolation of labeled phospholipoprotein (PLP) after labeling intact cells with (125)I corroborates previous experiments which suggested a surface location for the protein portion of the phospholipoprotein (P(PLP)). Solvent extraction of cells and immunological evidence, including studies with ferritin-coupled antibodies, indicate that P(PLP) is located at the cell surface and may also be within the cell envelope. These experiments suggest that P(PLP) is the major cell surface protein in P. facilis. 相似文献
124.
Harry G. Rittenhouse J. Barry Rodda Bruce A. McFadden 《Journal of bacteriology》1973,113(3):1400-1403
Antibodies to a protein present in the cell envelope of Hydrogenomonas facilis agglutinate many gram-negative bacteria and a few gram-positive bacteria. Immunodiffusion studies of extracts from the various organisms tested indicate the presence of components sharing antigenic determinants with the cell envelope protein in all bacteria which can be agglutinated and a few that cannot. Cross-reacting components were not detected in extracts of Mycoplasma laidlawii, Anacystis nidulans, and several eukaryotic organisms. 相似文献
125.
Finite difference analysis of respiratory heat transfer 总被引:2,自引:0,他引:2
Ingenito E. P.; Solway J.; McFadden E. R. Jr; Pichurko B. M.; Cravalho E. G.; Drazen J. M. 《Journal of applied physiology》1986,61(6):2252-2259
A numerical computer model of heat and water transfer within the tracheobronchial tree of humans was developed based on an integral formulation of the first law of thermodynamics. Simulation results were compared with directly measured intraluminal airway temperature profiles previously obtained in normal human subjects, and a good correlation was demonstrated. The model was used to study aspects of regional pulmonary heat transfer and to predict the outcomes of experiments not yet performed. The results of these simulations show that a decrease in inspired air temperature and water content at fixed minute ventilation produces a proportionately larger increase in heat loss from extrathoracic airways relative to intrathoracic, whereas an increase in minute ventilation at fixed inspired air conditions produces the opposite pattern, with cold dry air penetrating further into the lung, and that changes in breathing pattern (tidal volume and frequency) at fixed minute ventilation and fixed inspiratory-to-expiratory (I/E) ratio do not affect local air temperature profiles and heat loss, whereas changes in I/E ratio at fixed minute ventilation do cause a significant change. 相似文献
126.
Free ribulose hisphosphate (RuBP4?) rather than its magnesium complex (RuBP-Mg2?) was the apparent substrate for spinach ribulose bisphosphate carboxylase/oxygenase. The apparent Km for total RuBP (pH 8.0 at 30° C) increased with increasing Mg2+ concentrations from 11.6 μM at 13.33 mM Mg2+ to 32.6 μM at 40.33 mM Mg2+. Similarly the apparent Km for RuBP-Mg2? complex increased with increasing Mg2+ from 9.4 μM at 13.33 mM Mg2+ to 29.7 μM at 40.33 mM Mg2+. However, the Km values for uncomplexed RuBP4? were independent of the (saturating) concentration of Mg2+ (Km=2.2 μM). The Vmax did not vary with the changing concentrations of Mg2+. In contrast, the Km for total RuBP remained constant with varying Mg2+ concentrations (Km=59.5 μM) for the enzyme from R. rubrum. The apparent Km for the RuBP-Mg2? complex decreased with increasing Mg2+ concentrations from 16.0 μM at 7.5 mM Mg2+ to 5.9 μM at 27.5 mM Mg2+. The initial velocity for the C. vinosum enzyme was also found to be independent of the (saturating) concentration of Mg2+ when total RuBP was varied in the assay. Thus the response to total RuBP by these two bacterial enzymes, which markedly differ in structure, was closely similar. 相似文献
127.
Graft-versus-host disease (GVHD) is a potentially lethal clinical complication arising from the transfer of alloreactive T lymphocytes into immunocompromised recipients. Despite conventional methods of T cell depletion, GVHD remains a major challenge in allogeneic hematopoietic cell transplant. Here, we demonstrate a novel method of preventing GVHD by ex vivo treatment of primary human hematopoietic cell sources with myxoma virus, a rabbit specific poxvirus currently under development for oncolytic virotherapy. This pretreatment dramatically increases post-transplant survival of immunocompromised mice injected with primary human bone marrow or peripheral blood cells and prevents the expansion of human CD3(+) lymphocytes in major recipient organs. Similar viral treatment also prevents human-human mixed alloreactive T lymphocyte reactions in vitro. Our data suggest that ex vivo virotherapy with myxoma virus can be a simple and effective method for preventing GVHD following infusion of hematopoietic products containing alloreactive T lymphocytes such as: allogeneic hematopoietic stem and progenitor cells, donor leukocyte infusions and blood transfusions. 相似文献
128.
The mitochondrion of Plasmodium species is a validated drug target. However, very little is known about the functions of this organelle. In this review, we utilize data available from the Plasmodium falciparum genome sequencing project to piece together putative metabolic pathways that occur in the parasite, comparing this with the existing biochemical and cell biological knowledge. The Plasmodium mitochondrion contains both conserved and unusual features, including an active electron transport chain and many of the necessary enzymes for coenzyme Q and iron-sulphur cluster biosynthesis. It also plays an important role in pyrimidine metabolism. The mitochondrion participates in an unusual hybrid haem biosynthesis pathway, with enzymes localizing in both the mitochondrion and plastid organelles. The function of the tricarboxylic acid cycle in the mitochondrion is unclear. We discuss directions for future research into this fascinating, yet enigmatic, organelle. 相似文献
129.
Climate tolerances and trait choices shape continental patterns of urban tree biodiversity 下载免费PDF全文
130.