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91.
Christelle David Laurent Bischoff Hervé Meudal Catherine Llorens-Cortes Bernard Pierre Roques Marie-Claude Fournié-Zaluski 《Letters in Peptide Science》1997,4(4-6):411-414
In order to study the physiological role of aminopeptidase A (APA),several -mercapto--amino acyl dipeptides were synthesized toobtain compounds having a high affinity for APA and a high selectivityversus aminopeptidase N (APN). Sulfonamide and carboxylate moieties whichhave been shown to be recognized by the S1 subsite of theenzyme were introduced on the side chain of the -mercapto--aminoacyl sub-unit, the latter being coupled to dipeptides optimized to interactwith the S1 andS2 subsites by means of combinatorialchemistry. Good affinities (16 nM) were obtained, the selectivity factorsbeing up to 160-fold versus APN. 相似文献
92.
R. L. Wolff Bernard Comps Anne M. Marpeau Laurent G. Deluc 《Trees - Structure and Function》1997,12(2):113-118
The fatty acid compositions of the seed oils from ten pine species have been established by capillary gas-liquid chromatography
of the methyl esters. With regard to either normal fatty acids or Δ5-olefinic acids, the general pattern of fatty acids did
not differ from that of other pine seed oils reported previously. The main fatty acid was linoleic (9,12–18:2) acid (44.4–57.1%),
followed by either oleic (9–18:1) acid (13.4–24.5%) or pinolenic (5,9,12–18:3) acid (1.5–25.2%). When applying multivariate
analyses to the chemometric data (13 variables) of 49 pine species (ca. 40% of the living pine species), it was possible to
distinguish between several sections: Pinea, Longifolia, Halepensis, Ponderosa-Banksiana, Sylvestris, and Cembra. The latter section was clearly divided into two sub-groups. A few species that presented a low overall content of Δ5-olefinic
acids, and that grow in warm-temperate regions, were isolated from the bulk of other pine species. It is hypothesized that
Δ5-olefinic acids might be related to cold-acclimation.
Received: 5 June 1997 / Accepted: 17 August 1997 相似文献
93.
Marc Lecouvey Céline Frochot Laurent Miclo Piotr Orlewski Michel Marraud Jean-Luc Gaillard Manh Thong Cung Régis Vanderesse 《Letters in Peptide Science》1997,4(4-6):359-364
The conformation of a benzodiazepine-like decapeptide corresponding tothe YLGYLEQLLR fragment of a casein has been examined in a sodium dodecylsulfate micellar medium using circular dichroism, two-dimensional1H NMR spectroscopy and restrained molecular dynamicssimulation. The decapeptide adopts an amphipathic 310-helicoidstructure in which theE6···R10 ionic bridgestabilizes the C-terminus. 相似文献
94.
95.
96.
Laurent Chauvaud Jacky Cosson Marc Suquet Roland Billard 《Environmental Biology of Fishes》1995,43(4):341-349
Synopsis Turbot sperm motility is observed using dark field microscopy and stroboscopic illumination combined with video recording. Sperm motility is triggered by dilution of spermatozoa in sea water or in non ionic media (glucose or saccharose), presenting osmotic pressure ranging from 300 to 2100 mOsmol. The percentage of motile spermatozoa reaches 100% under conditions of osmotic pressure of 300 to 1100 mOsmol and pH close to 8.0. In full sea water, glucose or saccharose solutions an agglutination of spermatozoa is observed; this is prevented by addition of bovine serum albumin (5 mg ml–1). Immediately after transfer in activation solutions, 100% spermatozoa are motile in most samples freshly stripped. This percentage drops suddenly between 15 and 30% after 70 to 100 sec. The beat frequency remains at a constant value of 50 Hz during 40 s post activation and then drops suddenly between 15 and 30 Hz. The spermatozoa velocity is about 200 micrometers s–1 during 30 to 40 s and then declines to a stable value of 100 micrometers s–1 at 50 s post activation. After 1.20 mn, more and more spermatozoa become motionless. The minimum calculated and averaged distance covered during 1.20 min, is about 12 mm. The high performances of turbot spermatozoa motility are interpreted as a compensatory mechanism for the low sperm production. 相似文献
97.
Ursula Schulze-Gahmen Jeroen Brandsen Heather D. Jones David O. Morgan Laurent Meijer Jaroslav Vesely Sung-Hou Kim 《Proteins》1995,22(4):378-391
Cyclin-dependent kinases (CDKs) are conserved regulators of the eukaryotic cell cycle with different isoforms controlling specific phases of the cell cycle. Mitogenic or growth inhibitory signals are mediated, respectively, by activation or inhibition of CDKs which phosphorylate proteins associated with the cell cycle. The central role of CDKs in cell cycle regulation makes them a potential new target for inhibitory molecules with anti-proliferative and/or anti-neoplastic effects. We describe the crystal structures of the complexes of CDK2 with a weakly specific CDK inhibitor, N6-(δ2-isopentenyl)adenine, and a strongly specific inhibitor, olomoucine. Both inhibitors are adenine derivatives and bind in the adenine binding pocket of CDK2, but in an unexpected and different orientation from the adenine of the authentic ligand ATP. The N6-benzyl substituent in olomoucine binds outside the conserved binding pocket and is most likely responsible for its specificity. The structural information from the CDK2-olomoucine complex will be useful in directing the search for the next generation inhibitors with improved properties. © 1995 Wiley-Liss, Inc. 相似文献
98.
Interspecies recombination In nature: a meningococcus that has acquired a gonococcal PIB porin 总被引:7,自引:0,他引:7
Julio A- Vázquez Sonsoles Berron Maria O'Rourke Gill Carpenter Edward Feil Noel H. Smith Brian G. Spratt 《Molecular microbiology》1995,15(6):1001-1007
A. vaginal isolate of Neisseria has been reported to resemble Neisseria meningitidis in biochemical characteristics but to react with serological reagents that are specific to the PI porin from Neisseria gonorrhoeae. We have confirmed that this isolate has the biochemical attributes of a meningococcus and have shown that it clusters among meningococcal Isolates on a dendrogram based on isoenzyme variation within housekeeping enzymes from populations of N. meningitidis and N. gonorrhoeae. Furthermore, the sequences of the fbp and adk genes were typical of those of N. meningitidis and were distinct from those of N. gonorrhoeae. However, the porB gene was very similar to the por genes of N. gonorrhoeae isolates that express the PIB class of outer-membrane porin (differing from one gonococcal por allele at only a single nucleotide site), and was clearly distinct from the porB genes of N. meningitidis. The isolate therefore appears to be a typical meningococcus, except that its porB gene has been replaced with the por gene from a gonococcus. 相似文献
99.
pAMβ1 resolvase has an atypical recombination site and requires a histone-like protein HU 总被引:1,自引:1,他引:0
The broad-host-range plasmid pAMβ1 from Gram-positive bacteria encodes a resolvase, designated Resβ, which shares homology with the proteins of the resolvase—invertase family. Here we report the purification and in vitro characterization of Resβ. This resolvase is particular in two aspects: it has an atypical binding site and requires a cofactor to promote resolution in vitro . Resβ binds to two regions within its resolution site res . One contains two inverted repeats (R1 and R2), the other contains only one repeat (R3). The cofactor required for resolution in vitro is present in crude extracts of both Bacillus subtilis and Escherichia coli and can be substituted by the E. coli histone-like protein HU. The possible mode of action of HU in the resolution process is discussed. 相似文献
100.
A thymocyte-specific alloantigen, designated AT (avian thymus) –1.1, has been detected in Cornell C strain (CS) and Obese strain (OS) chickens, the latter being a strain derived from CS which develops a spontaneous form of autoimmune thyroiditis (SAT). Antisera specific for this antigen were developed first in a turkey immunized with thymocytes from an OS chicken and, later, in AT-1.1-negative CS chickens immunized with AT-1.1-positive thymocytes. AT-1.1 was detected in 50–70% of cells in a thymus cell suspension, but was not seen on peripheral blood lymphocytes, erythrocytes, or cells from bursa, spleen, kidney, liver, or brain. It was present on thymocytes of chickens at all ages tested, from 1 day to 6 months of age. AT-1.1 was not detected in six chicken lymphoid tumor cell lines tested, and birds expressing it were found to be negative for the presence of Marek's disease viral antigens. Pedigree studies on 287 (OS × CS)F2 chickens demonstrated that AT-1.1 is expressed in a dominant or codominant manner, and the gene coding for this antigen was not linked to the B (major histocompatibility) complex. The genetics and tissue distributions of AT-1.1 indicate that it differs from thymus cell surface antigens, avian or mammalian, previously described. 相似文献