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391.
C. W. Sensen Robert L. Charlebois Cynthia Chow Ib Groth Clausen Bruce Curtis W. Ford Doolittle Michel Duguet Gael Erauso Terry Gaasterland Roger A. Garrett Paul Gordon I. Heikamp de Jong Alex C. Jeffries Catherine Kozera Nadine Medina Anick De Moors John van der Oost Hien Phan Mark A. Ragan Margaret E. Schenk Qunxin She Rama K. Singh Niels Tolstrup 《Extremophiles : life under extreme conditions》1998,2(3):305-312
The Sulfolobus solfataricus P2 genome collaborators are poised to sequence the entire 3-Mbp genome of this crenarchaeote archaeon. About 80% of the genome
has been sequenced to date, with the rest of the sequence being assembled fast. In this publication we introduce the genomic
sequencing and automated analysis strategy and present intial data derived from the sequence analysis. After an overview of
the general sequence features, metabolic pathway studies are explained, using sugar metabolism as an example. The paper closes
with an overview of repetitive elements in S. solfataricus. 相似文献
392.
Pavla Čapková Daniel Janeba Ludvík Beneš Klára Melánová Henk Schenk 《Journal of molecular modeling》1998,4(4):150-157
Molecular mechanics simulations using Cerius2 combined with X-ray diffraction and supported with vibrational spectroscopy have been used to investigate the layered structure of vanadyl phosphate VOPO4 intercalated with ethanol. This intercalated structure exhibits certain degree of disorder, which affects the diffraction diagram and obstructs the conventional structure analysis based on diffraction methods only. Present structure analysis is focused to the crystal packing in the interlayer space and layer stacking in the intercalate. The bilayer arrangement of ethanol molecules in the interlayer has been found, giving the basal spacing d = 13.21 Å, experimental d-value obtained from X-ray diffraction is 13.17 Å. One half from the total number of CH3CH2OH molecules is anchored with their oxygens to VOPO4 layers to complete vanadium octahedra and their orientation is not very strictly defined. The second half of ethanoles is linked with hydrogen bridges to the anchored etahanoles and sometimes also to the layer oxygens. Positions and orientations of these unachored ethanoles with respect to VOPO4 layers exhibit certain degree of disorder, resulting in the disorder in layer stacking. Molecular mechanics simulations revealed the character of this displacement disorder in layer stacking and enabled to determine the components of the displacement vector. 相似文献
393.
R M Scarborough D B Schenk G A McEnroe A Arfsten L L Kang K Schwartz J A Lewicki 《The Journal of biological chemistry》1986,261(28):12960-12964
A series of truncated atrial natriuretic peptide analogs were examined as a means of defining the structural requirements for receptor occupancy and stimulation of cyclic GMP accumulation in bovine aortic smooth muscle cells. It was determined that deletion of amino acids from the carboxyl and/or amino termini of the peptides diminished their ability to increase cyclic GMP levels. Deletion of amino acids from the carboxyl terminus had the greatest effect, and atrial natriuretic peptide analogs lacking the carboxyl-terminal phenylalanyl-arginyl-tyrosine tripeptide were 100-1000-fold less active than parent compounds in stimulating intracellular cyclic GMP accumulation. In marked contrast to the cyclic GMP effects, deletion of amino- and/or carboxyl-terminal amino acids had only minor effects on the affinity of the peptides for specific smooth muscle cell-associated receptors. Peptide analogs lacking the phenylalanyl-arginyl-tyrosine tripeptide bound to receptors with an affinity only 1.1-5-fold weaker than the parent compounds. Thus, there was no correlation between apparent receptor binding affinity of atrial natriuretic peptide analogs and potency of these same peptides for stimulating intracellular cyclic GMP accumulation. Furthermore, analogs that bound to receptors and failed to elicit significant cyclic GMP responses did not antagonize or modulate increases in cyclic GMP induced by parent compounds. These data are most consistent with the existence of multiple subpopulations of atrial natriuretic peptide receptors on aortic smooth muscle cells. 相似文献
394.
Rat hepatic (Na+, K+)-ATPase: alpha-subunit isolation by immunoaffinity chromatography and structural analysis by peptide mapping 总被引:6,自引:0,他引:6
The catalytic alpha-subunit of rat hepatic (Na+, K+)-ATPase (EC 3.6.1.3) has been isolated by immunoaffinity chromatography from microsomes solubilized in n-dodecyl octaethylene glycol monoether. The procedure employs an anticatalytic mouse monoclonal antibody ("9-A5") covalently linked to Sepharose 4B that specifically blocks phosphorylation of the sodium pump's alpha-subunit from [gamma-32P]ATP [Schenk, D. B., Hubert, J.J., & Leffert, H.L. (1984) J. Biol. Chem. 259, 14941-14951]. The hepatic subunit is virtually identical with purified rat, dog, and human renal alpha-subunits as judged by its apparent molecular weight after polyacrylamide gel electrophoresis in sodium dodecyl sulfate (Mr 92K) and its two-dimensional tryptic and chymotryptic peptide maps on cellulose-coated thin-layer plates. In contrast, the structures of authentic renal beta-subunits from the three species differ significantly from each other as judged by their peptide maps; no detectable homologies are seen between their chymotryptic maps and those of putative hepatic "beta"-subunits (Mr 50K and 55K) eluted from 9-A5-Sepharose. Additional studies of ouabain-sensitive 86Rb+ uptake in primary cultures of adult rat hepatocytes reveal inhibition curves with single inflection points (ID50 = 0.1 mM ouabain) in the absence or presence of pump-stimulating peptides like insulin, glucagon, and epidermal growth factor. These findings indicate that rat hepatocytes express only one of two known structurally conserved forms of catalytic subunit (the renallike alpha form) and, if at all, structurally divergent forms of the sodium pump's beta-subunit. In addition, immunoaffinity chromatography with 9-A5-Sepharose facilitates the isolation of (Na+, K+)-ATPases from nonrenal tissues with low levels of sodium pumps. 相似文献
395.
Cellular fatty acid composition of 14 strains from the four species of Azospirillum was determined by gas chromatographic analysis. All strains of Azospirillum lipoferum and Azospirillum brasilense were similar in fatty acid data, thus not revealing an expected distinction between the two long established species. Strains of both Azospirillum halopraeferens and Azospirillum amazonense, however, differed significantly from this first group of strains. 相似文献
396.
J G Porter R M Scarborough Y Wang D Schenk G A McEnroe L L Kang J A Lewicki 《The Journal of biological chemistry》1989,264(24):14179-14184
A general structure for the atrial natriuretic peptide clearance receptor (ANP C-receptor) has been proposed based on hydropathicity analysis of the deduced amino acid sequence of this membrane protein (Fuller, F., Porter, J.G., Arfsten, A., Miller, J., Schilling, J., Scarborough, R.M., Lewicki, J.A., and Schenk, D.B. (1988) J. Biol. Chem. 263, 9395-9401). The ANP C-receptor is believed to possess a large amino-terminal extracellular domain (436 amino acids), a single hydrophobic transmembrane anchor (23 amino acids), and a short cytoplasmic tail (37 amino acids). As a means of testing the structure and proposed cellular orientation of this protein, we have employed the technique of in vitro mutagenesis to prepare a receptor mutant (anc-) lacking the transmembrane and cytoplasmic domains. Expression of this mutant in mammalian cells using a vaccinia virus vector results in secretion of a truncated soluble form of the ANP C-receptor which binds native ANP and synthetic ANP analogs with a specificity similar to that of the native ANP C-receptor. In contrast to the native ANP C-receptor that exists predominantly as a homodimer on the cell surface, the secreted receptor exists as a monomeric species. The results are consistent with the proposed structure of this receptor with the amino-terminal domain containing the ANP-binding site oriented extracellular to the plasma membrane. In addition, these data demonstrate that the receptor does not require association with the plasma membrane or its native dimeric configuration in order to bind ANP ligands with high affinity and specificity. 相似文献
397.
John J. Schenk 《PloS one》2016,11(1)
Secondary calibrations (calibrations based on the results of previous molecular dating studies) are commonly applied in divergence time analyses in groups that lack fossil data; however, the consequences of applying secondary calibrations in a relaxed-clock approach are not fully understood. I tested whether applying the posterior estimate from a primary study as a prior distribution in a secondary study results in consistent age and uncertainty estimates. I compared age estimates from simulations with 100 randomly replicated secondary trees. On average, the 95% credible intervals of node ages for secondary estimates were significantly younger and narrower than primary estimates. The primary and secondary age estimates were significantly different in 97% of the replicates after Bonferroni corrections. Greater error in magnitude was associated with deeper than shallower nodes, but the opposite was found when standardized by median node age, and a significant positive relationship was determined between the number of tips/age of secondary trees and the total amount of error. When two secondary calibrated nodes were analyzed, estimates remained significantly different, and although the minimum and median estimates were associated with less error, maximum age estimates and credible interval widths had greater error. The shape of the prior also influenced error, in which applying a normal, rather than uniform, prior distribution resulted in greater error. Secondary calibrations, in summary, lead to a false impression of precision and the distribution of age estimates shift away from those that would be inferred by the primary analysis. These results suggest that secondary calibrations should not be applied as the only source of calibration in divergence time analyses that test time-dependent hypotheses until the additional error associated with secondary calibrations is more properly modeled to take into account increased uncertainty in age estimates. 相似文献
398.
399.
400.
Lettuce was grown in nutrient solution under fluctuating climatic conditions in the greenhouse. The maximum nitrate inflow (Imax) was measured twice a week to validate a model for calculating Imax, that was developed for constant conditions in a growth chamber.Growth and Imax were very similar between greenhouse and growth chamber plants, so that the model was able to predict Imax very precisely. The daily maximum nitrate inflow was calculated and its dependency on fluctuating temperature could be shown. 相似文献