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11.
S Benyhe G Hoffmann E Varga S Hosztafi G Toth A Borsodi M Wollemann 《Life sciences》1989,44(24):1847-1857
Oxymorphazone (at doses of 50-200 mg/kg) was found to be a relatively weak antinociceptive drug in intact frog (Rana esculenta) when acetic acid was used as pain stimulus. Frogs remained analgesic for at least 48 hrs following oxymorphazone (200 mg/kg) administration. The ligand increased the latency of wiping reflex in spinal frogs too. These effects were blocked by naloxone. In equilibrium binding studies (3H)oxymorphazone had high affinity to the opioid receptors of frog brain and spinal cord as well (apparent Kd values were 8.9 and 10.6 nM, respectively). Kinetic experiments show that only 25% of the bound (3H)oxymorphazone is readily dissociable. Preincubation of the membranes with labeled oxymorphazone results in a washing resistant inhibition of the opioid binding sites. At least 70% of the (3H)oxymorphazone specific binding is apparently irreversible after reaction at 5 nM ligand concentration, and this can be enhanced by a higher concentration of tritiated ligand. 相似文献
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A mutation in the small (alpha) subunit of glycyl-tRNA synthetase affects amino acid activation and subunit association parameters 总被引:1,自引:0,他引:1
A strategy was designed to isolate mutants of glycyl-tRNA synthetase that are altered at the amino acid binding site, including a class with altered amino acid specificity. For this purpose, the plasmid pBR322 was mutated so that the codon (AGC) of the active site Ser-68 in the beta-lactamase gene was changed to the glycine codon GGC to inactivate the encoded enzyme. Suppressors that increase the amount of beta-lactamase activity of the Gly-68 allele of beta-lactamase were isolated and some mapped to the gene encoding glycyl-tRNA synthetase (glyS). While in vitro misaminoacylation of tRNA(Gly) with serine was not detected for any of the mutants, glycyl-tRNA synthetase activity was altered. One severely affected glyS mutant (N302) was studied in more detail. For this mutant, a single Pro-61----Leu substitution in the alpha chain confers an elevation of the Km values for glycine (25-fold) and for ATP (45-fold) in the aminoacylation reaction, but only a minor perturbation of the Km for tRNA. There also was a severely reduced adenylate synthesis activity (greater than 100-fold). In addition, a nonlinear dependence between aminoacylation activity and enzyme concentration was observed which implies that the alpha chain Pro-61----Leu mutation has disrupted the functionally essential subunit interactions of the holoenzyme. The results of the preceding paper have shown that the alpha chain and parts of the beta chain are required for aminoacylation and adenylate synthesis activity. The results of this study suggest that the alpha chain specifically contributes to amino acid and to ATP binding in a way that is affected by proper subunit interactions. 相似文献
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Larry A. Jones Diane K. Jordan Kutay Taysi Arnold W. Strauss Joseph K. Toth 《Human genetics》1979,51(1):37-42
Summary A partial duplication of the distal segment of the long arm of chromosome 5 (q31qter) was observed in an infant with congenital malformations and dysmorphic features. The phenotypically normal father had a balanced translocation between the long arm of chromosome 5 and the short arm of chromosome 9: 46,XY,t(5;9)(q31;p24).The clinical and cytogenetic data obtained from six patients with partial duplications of two different long arm segments of chromosome 5 suggest that partial duplication of the distal long arm of chromosome 5 is associated with microcephaly, hypertelorism, epicanthus, strabismus, large upper lip, low-set, dysplastic ears, in addition to growth and psychomotor retardation. Partial duplication of the proximal part of the long arm of chromosome 5, on the other hand, is associated mainly with musculoskeletal abnormalities including muscle hypotrophy and hypotonia, scoliosis, lordosis, pectus carinatum, cubitus valgus, and genu valgum, in addition to psychomotor retardation. The dysmorphic features in this latter group include a bulging forehead, short nose, thick upper lip, low-set protruding ears and tapering, thin fingers. 相似文献
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Current identification methods for the soft rot erwinias are both imprecise and time-consuming. We have used the 16S-23S rRNA intergenic transcribed spacer (ITS) to aid in their identification. Analysis by ITS-PCR and ITS-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. The ITS was amplified from Erwinia and other genera using universal PCR primers. After PCR, the banding patterns generated allowed the soft rot erwinias to be differentiated from all other Erwinia and non-Erwinia species and placed into one of three groups (I to III). Group I comprised all Erwinia carotovora subsp. atroseptica and subsp. betavasculorum isolates. Group II comprised all E. carotovora subsp. carotovora, subsp. odorifera, and subsp. wasabiae and E. cacticida isolates, and group III comprised all E. chrysanthemi isolates. To increase the level of discrimination further, the ITS-PCR products were digested with one of two restriction enzymes. Digestion with CfoI identified E. carotovora subsp. atroseptica and subsp. betavasculorum (group I) and E. chrysanthemi (group III) isolates, while digestion with RsaI identified E. carotovora subsp. wasabiae, subsp. carotovora, and subsp. odorifera/carotovora and E. cacticida isolates (group II). In the latter case, it was necessary to distinguish E. carotovora subsp. odorifera and subsp. carotovora using the alpha-methyl glucoside test. Sixty suspected soft rot erwinia isolates from Australia were identified as E. carotovora subsp. atroseptica, E. chrysanthemi, E. carotovora subsp. carotovora, and non-soft rot species. Ten "atypical" E. carotovora subsp. atroseptica isolates were identified as E. carotovora subsp. atroseptica, subsp. carotovora, and subsp. betavasculorum and non-soft rot species, and two "atypical" E. carotovora subsp. carotovora isolates were identified as E. carotovora subsp. carotovora and subsp. atroseptica. 相似文献
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Ohne Zusammenfassung 相似文献
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Microbial mutagenicity of selected hydrazines 总被引:1,自引:0,他引:1
Selected hydrazines and related compounds were examined for their mutagenic activity in S. typhimurium strains TA1535 and TA1537. These in vitro assays were conducted with and without metabolic activation by Aroclor-induced rat-liver enzymes. Relatively high levels of mutagenicity were observed with phenylhydrazine X HCl, methylhydrazine, N'-acetyl-4-(hydroxymethyl)phenylhydrazine, and 4-(hydroxymethyl)benzenediazonium tetrafluoroborate, the stabilized salt of a carcinogenic metabolite of agaritine; only low levels of mutagenicity were observed with other compounds, although most are strong carcinogens. Several of the compounds were highly toxic to the bacteria, and detection of mutagenicity was enhanced by calculating the increase in mutagenic activity on the basis of the surviving fractions of bacteria. 相似文献