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231.
Walter R. A. van Heumen Gregg T. Nagle Alexander Kurosky 《Cell and tissue research》1995,279(1):13-24
The atrial gland is an exocrine organ that secretes into the oviduct of Aplysia californica and expresses three homologous genes belonging to the egglaying hormone gene family. Although post-translational processing of the egg-laying hormone precursor in the neuroendocrine bag cells has been examined in detail, relatively little is known about the post-translational processing of egg-laying hormone-related gene products in the atrial gland. A combination of morphologic techniques that included light-microscopic histology and immunocytochemistry, transmission electron microscopy, and immuno-electron microscopy were used to localize egg-laying hormone-related peptides in the atrial gland and to evaluate the characteristic morphology of their secretory cells. Results of these studies showed that there were at least three major types of secretory cells in the atrial gland (types 1–3). Significantly, of these three cell types, only type 1 was immunoreactive to antisera against egg-laying hormone-related precursor peptides. The immunoreactivity studies established that all three egg-laying hormone-related precursor genes are expressed in type-1 cells and indicated that the processing of these precursors also occurs within the secretory granules of this cell type. Evidence was also obtained that proteolytic processing of the egg-laying hormone-related precursors differed significantly from that observed in the bag cells. In contrast to the bag cells, the NH2-terminal and COOH-terminal products of the egg-laying hormone-related precursors of the atrial gland were not sorted into different types of vesicles. 相似文献
232.
Nicholas J. Lench John Thompson Alexander F. Markham Philip A. Robinson 《Human genetics》1995,96(3):369-370
The polymerase chain reaction was used to detect polymorphisms in a (CGG) trinucleotide repeat sequence in the 5 region of the human HHR6B DNA repair gene on chromosome 5q23-31 相似文献
233.
234.
Alexander Steinkasserer Tania Jones Denise Sheer Karl Koettnitz Joachim Hauber Dorian Bevec 《Genomics》1995,25(3)
The eukaryotic initiation factor 5A (eIF-5A) has been identified as an essential cofactor for the HIV-1 trans-activator protein Rev. Rev plays a key role in the complex regulation of HIV-1 gene expression and thereby in the generation of infectious virus particles. Expression of eIF-5A is vital for Rev function, and inhibition of this interaction leads to a block of the viral replication cycle. In humans, four different eIF-5A genes have been identified. One codes for the eIF-5A protein and the other three are pseudogenes. Using a panel of somatic rodent—human cell hybrids in combination with fluorescence in situ hybridization analysis, we show that the four genes map to threedifferent chromosomes. The coding eIF-5A gene (EIF5A) maps to 17p12–p13, and the three pseudogenes EIF5AP1, EIF5AP2, and EIF5AP3 map to 10q23.3, 17q25, and 19q13.2, respectively. This is the first localization report for a eukaryotic cofactor for a regulatory HIV-1 protein. 相似文献
235.
Summary A method for quantification of distances between amide hydrogens using only the 3D NOESY-HMQC experiment recorded on a 15N-labelled protein is presented. This method is based on an approximate expression of the NOE intensities between amide hydrogens obtained from continuum modelling of the non-amide spins; this expression is used in a distance calculation algorithm. The algorithm has been named CROWD, standing for Continuum approximation of Relaxati On path Ways between Dilute spins. This approximation as well as the CROWD algorithm are tested on a simulated case; the CROWD algorithm is then applied to experimental data, measured on a fragment of bacteriorhodopsin. 相似文献
236.
Dmitry E. Nolde Alexander G. Sobol Kirill A. Pluzhnikov Eugene V. Grishin Alexander S. Arseniev 《Journal of biomolecular NMR》1995,5(1):1-13
Summary Two-dimensional 1H NMR techniques were used to determine the spatial structure of ectatomin, a toxin from the venom of the ant Ectatomma tuberculatum. Nearly complete proton resonance assignments for two chains of ectatomin (37 and 34 amino acid residues, respectively) were
obtained using 2D TOCSY, DQF-COSY and NOESY experiments. The cross-peak volumes in NOESY spectra were used to define the local
structure of the protein and generate accurate proton-proton distance constraints employing the MARDIGRAS program. Disulfide
bonds were located by analyzing the global fold of ectatomin, calculated with the distance geometry program DIANA. These data,
combined with data on the rate of exchange of amide protons with deuterium, were used to obtain a final set of 20 structures
by DIANA. These structures were refined by unrestrained energy minimization using the CHARMm program. The resulting rms deviations
over 20 structures (excluding the mobile N- and C-termini of each chain) are 0.75 ? for backbone heavy atoms, and 1.25 ? for
all heavy atoms. The conformations of the two chains are similar. Each chain consists of two α-helices and a hinge region
of four residues; this forms a hairpin structure which is stabilized by disulfide bridges. The hinge regions of the two chains
are connected together by a third disulfide bridge. Thus, ectatomin forms a four-α-helical bundle structure. 相似文献
237.
Marianne Borloo Koen Augustyns Alexander Belyaev Ingrid de Meester Anne-Marie Lambeir Filip Goossens Willy Bollaert Padinchare Rajan Simon Scharpé Achiel Haemers 《Letters in Peptide Science》1995,2(3-4):198-202
Summary A series of azaproline dipeptides with various N-substituents were synthesized as possible active-site-directed inhibitors of two proline-specific serine proteases, dipeptidyl peptidase IV and prolyl oligopeptidase. Compounds with semicarbazide, carbazate, acylhydrazine and sulphonylhydrazine structures were tested. Some compounds show moderate activity, i.e., in the millimolar range. 相似文献
238.
Alexander Tschopp Augusto Cogoli Marian L. Lewis Dennis R. Morrison 《Journal of biotechnology》1984,1(5-6)
Attachment to a substrate and survival of human embryonic kidney (HEK) cells have been tested in an incubator installed in the flight-deck of the Space Shuttle ‘Challenger’ during its eighth mission.HEK cells are producing the enzyme urokinase and are presently investigated as candidates for electrophoretic separation in an apparatus developed and manufactured by McDonnell Douglas.Attachment of HEK cells to a substrate is mandatory for survival and production of urokinase after electrophoretic separation.Analysis of the samples shows that cells adhere, spread and survive in microgravity (< 10−3 ×g) conditions as well as the ground controls at 1 × g. This result represents an important step towards further bioprocessing in space. 相似文献
239.
A study was conducted to seek means to increase the colonization of the rhizosphere of soybeans (Glycine max L. Merrill) by Rhizobium japonicum. For this purpose, a strain of R. japonicum that was resistant to benomyl, streptomycin, and erythromycin was used. The numbers of R. japonicum rose quickly in the first 2 days after soybean seeds were planted in soil and then rapidly fell. The decline was slower if the seeds were coated with benomyl. This fungicide reduced the numbers of bacteria and protozoa in the rhizosphere, but the effect became less or disappeared as the plants grew. In sterile soil inoculated with R. japonicum and a mixture of microorganisms, the numbers of R. japonicum were usually lower if protozoa were present than if they were absent. Nodulation and plant yield were increased by the addition of benomyl to soybean seeds sown in sterile soil inoculated with R. japonicum and a mixture of microorganisms. The addition of streptomycin and erythromycin to soil stimulated the growth of R. japonicum but inhibited other bacteria in the presence or absence of soybeans. The data indicate that colonization can be increased by the use of antimicrobial agents and R. japonicum strains resistant to those inhibitors. 相似文献
240.
Alexander V. Itkes Kyril T. Turpaev Olga N. Kartasheva Constantin A. Kafiam Evgenii S. Severin 《Molecular and cellular biochemistry》1984,59(1-2):165-171
Summary Dihydrofolate synthetase (EC 6.3.2.12) from N. gonorrhoeae was isolated and enzyme characteristics were determined. The purified enzyme was found quite stable when stored at –60 °C. About 50% of the enzyme activity wag destroyed within 6 weeks when kept at 4 °C. Maximum velocity was observed at pH 9.3. The enzyme required a monovalent cation, K+ or NH4
+ , and divalent cation, Mg2+ or Mn2+ for its function. ATP at 5 mM concentration gave maximum activity. Km values for dihydropteroate and L-glutamate at pH 9.3 were 3.5 × 10–5 M and 6.5 × 10–4 M, respectively. Patterns of product inhibition by dihydrofolate were found to be non-competitive with respect to dihydropteroate, having a Ki value of 5.1 ± 0.8 × 10–4 M, and competitive with respect to L-glutamate, having a Ki value of 6.2 × 10–4 M. 相似文献