共查询到20条相似文献,搜索用时 15 毫秒
1.
Ronald M. Hamelik Mead M. McCabe 《Biochemical and biophysical research communications》1982,106(3):875-880
An inhibitor of , endodextranase was detected in proteins prepared from batch cultures of , strains representing serotypes through . Affinity chromatography of strain 6715-49 proteins, which apparently were free of endodextranase activity, yielded an active endodextranase and, in a separate peak, the endodextranase inhibitor. The presence of the inhibitor in culture fluids accounts for the absence of endodextranase activity in batch-grown cultures of , known to produce this enzyme. 相似文献
2.
Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development (embryo culture) and (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect development to the blastocyst stage of (1) 8-cell hamster embryos (zonae removed by a combined enzymic-mechanical procedure), (2) bovine morulae (zonae removed by mechanical means only) (3) early bovine blastocysts (zonae removed by the enzymic-mechanical technique).Zona-free hamster embryos formed significantly fewer viable fetuses than did zona-intact embryos. The lower incidence of fetal development observed following transfer of zona-free 8-cell hamster embryos may have resulted in part from the formation of chimeras by fusion of these embryos . Such fusion was observed to occur between zona-free embryos placed in close proximity. The proportion of pregnancies resulting from transfer of bovine blastocysts cultured from zona-free morulae was similar to that of zona-intact embryos.In this study we have demonstrated that (1) enzymic and mechanical procedures used to remove zonae pellucidae from uterine-stage hamster and bovine embryos do not adversely affect subsequent development of these embryos and and (2) zonae pellucidae are not required for normal development of these embryos. These findings have implications for microsurgery of mammalian embryos and for embryo transfer. 相似文献
3.
, the initial membrane enzyme in the biosynthesis of peptidoglycan, requires a lipid microenvironment for function. was reversibly intercalated into membranes to perturb the hydrophobic interactions in this microenvironment in order to define further the role of lipid. In the concentration range for maximal stimulation of enzymic activity (0.12–0.18 M), causes a 40% decrease in the fluorescence emission of the dansylated product, undecaprenyl . Since no change in emission maximum occurs below 22°C in the presence of 0.12 M , it is concluded that intercalation of this alkanol causes an increase in fluidity. Above 22°C this concentration of causes both a decrease in the fluorescence emission and a red shift in the emission maximum. It is concluded that a polarity change as well as fluidity change occurs above 22°C. also causes a significant change in the phase transition experienced by the dansylated lipid product. Thus, it is possible with , e.g. , to perturb lipid-translocase interactions resulting in an increase in fluidity in the microenvironment of the enzyme. This change in fluidity correlates with a stimulation of enzymic activity. 相似文献
4.
Evelyne Rouer Patrick Dansette Philippe Beaune Jean-Paul Leroux 《Biochemical and biophysical research communications》1980,95(1):41-46
The thermally-induced changes of a cytochrome P-450 dependent activity (ethoxycoumarin-O-deethylase) and of the fluorescence polarization of diphenylhexatriene were compared in microsomes from lean, and mice. In lean mice, biphasic plots were obtained with break points in the same range of temperature by both methods, whereas, in and mice, no discontinuities were observed. These results may be related to a modified fatty acid composition of microsomal membranes in mutant mice. They exemplify the influence of the lipid environment on the monooxygenase system as also shown by the modified binding constants of cytochrome P-450 towards type II substrates in mice. 相似文献
5.
Randall S. Alberte Alan L. Friedman Darel L. Gustafson Marla S. Rudnick Harvard Lyman 《BBA》1981,635(2):304-316
The present study examined the protein associations and energy transfer characteristics of chlorophyll c and fucoxanthin which are the major light-harvesting pigments in the brown and diatomaceous algae. It was demonstrated that sodium dodecyl sulfate (SDS)-solubilized photosynthetic membranes of these species when subjected to SDS polyacrylamide gel electrophoresis yielded three spectrally distinct pigment-protein complexes. The slowest migrating zone was identical to complex I, the SDS-altered form of the P-700 chlorophyll a-protein. The zone of intermediate mobility contained chlorophyll c and chlorophyll a in a molar ratio of 2 : 1, possessed no fucoxanthin, and showed efficient energy transfer from chlorophyll c to chlorophyll a. The fastest migrating pigment-protein zone contained fucoxanthin and chlorophyll a, possessed no chlorophyll c, and showed efficient energy transfer from fucoxanthin to chlorophyll a. It is demonstrated that the chlorophyll and the chlorophyll complexes are common to the brown algae and diatoms examined, and likely share similar roles in the photosynthetic units of these species. 相似文献
6.
Yuji Kamiya Akira Sakurai Nobutaka Takahashi 《Biochemical and biophysical research communications》1980,94(3):855-860
Rhodotorucine which induces mating tube formation of cells in is metabolized rapidly by cells. By use of labeled rhodotorucine , the degradation was found to be proteolytic. Two peptide fragments Tyr-Pro-Glu-Ile-Ser-Trp-Thr-Arg and Asn-Gly-Cys(S-farnesyl) were identified as the metabolites. Proteolysis of the pheromone mainly occurred on the cell surface. Culture filtrate of cells at log phase did not metabolize rhodotorucine . 相似文献
7.
Guanylate cyclase from crude homogenates of vegetative has been characterized. It has a pH optimum of 8.0, temperature optimum of 25°C and requires 1 mM dithiothreitol for optimal activity. It strongly prefers Mn++ to Mg++ as divalent cation, requires Mn++ in excess of GTP for detectable activity, and is inhibited by high Mn++ concentrations. It has an apparent Km for GTP of approximately 517 μM at 1 mM excess Mn++.The specific activity of guanylate cyclase in vegetative homogenates is 50–80 pmoles cGMP formed/min/mg protein. Most of the vegetative activity is found in the supernatant of a 100,000 x g spin (S100). The enzyme is relatively unstable. It loses 40% of its activity after 3 hours storage on ice. Enzyme activity was measured from cells that had been shaken in phosphate buffer for various times. It was found that the specific activity changed little for at least 8 hours. Cyclic AMP at 10?4 M did not affect the guanylate cyclase activity from crude homogenates of vegetative or 6 hour phosphate-shaken cells. 相似文献
8.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
9.
OKY-1581 is an effective inhibitor of thromboxane synthesis and . The generation of thromboxane B2 (TxB2), prostaglandin E (PGE) and prostaglandin F (PGF) was measured following clotting and during platelet aggregation induced by collagen. The presence of OKY 1581 either or caused a reduction in TxB2 generation during clotting and platelet aggregation with a concomitant increase in PGE and PGF. The effect could be observed two hours after oral or subcutaneous administration of 5 to 100 mg per rabbit and lasted for 24 to 48 hours. The reduction in TxB2 was not accompanied by an inhibition of clotting or platelet aggregation. OKY-1581 appears to be a suitable agent for studying the role of TxB2 in atherosclerosis. 相似文献
10.
J.A. Pérez-González A. Jiménez 《Biochemical and biophysical research communications》1984,125(3):895-901
The paromomycin producing organism is resistant to this antibiotic and contains a phosphotransferase which inactivates paromomycin. The gene encoding this enzyme has been inserted in the vector pIJ702 and then cloned in , selecting for paromomycin-resistance. Three plasmids have been isolated and one of them, pMJ1, contains a 2.2 kb insert with a single HindIII restriction site. Insertion of foreign DNA in this site blocks the expression of the phosphotransferase enzyme indicating that it is within the cloned gene. These findings provide a new dominant selective marker for cloning vectors with the versatility of insertional inactivation. 相似文献
11.
Phospholipid phase transitions. Effects of , , phenylalkyl alcohols and quatenary ammonium compounds
The interactions of a series of alcohols, acids and quaternary ammonium salts with a phosphatidylcholine-water model biomembrane (dipalmitoyl phosphatidylcholine) system have been studied using differential scanning calorimetry. In particular the effects of these molecules upon the lipid endothermic phase transitions were investigated over a range of concentrations. A variety of effects was observed. (a) Those molecules which shift or broaden the main lipid transition can also remove the pretransition endotherm. (b) and acids containing the same number of carbon atoms have very similar effects at molar concentrations up to 40%. Those molecules containing 12 or more carbon atoms raise the main lipid phase transition whilst those molecules containing 10 or less carbon atoms lower this transition temperature. (c) The phase diagram of stearoyl alcohol in the phosphatidylcholine-water system shows the formation of lipid-alcohol complexes. (d) Alkyl trimethyl ammonium bromides showed behaviour which differs considerably from and acids of the same chain length. (e) Other alkyltrialkyl and tetraalkylammonium bromides show that a variety of effects on the lipid phase transition can be obtained. (f) With the homologous series of phenylalkyl alcohols from benzyl alcohol to 4-phenyl butanol increasing the number of methylenes between the terminal OH and the benzene ring leads to greater interaction between solute and bilayer.The range of different effects obtained with the compounds studied offers a means for introducing various degrees and types of perturbation into membrane systems. 相似文献
12.
E.A. Hosein M. Lapalme E.B. Vadas 《Biochemical and biophysical research communications》1977,78(1):194-201
Differential scanning calorimetry of crude brain mitochondrial lipids obtained from control and morphine treated rats was carried out and the lipid phase transition measured. Morphine treatment resulted in a significant decrease in the temperature range and enthalpy of the phase transition. This effect was found to be dose dependent and reversible both and by naloxone. Studies with levorphanol and dextrorphan demonstrated stereospecificity. Furthermore, the ether precipitable fraction of total lipid extracts was shown to mediate the opiate response. 相似文献
13.
Werner Goebel 《Biochemical and biophysical research communications》1973,51(4):1000-1007
The dependence of the replication of several plasmids on the chromosome-determined initiation products, A and C, has been studied. The initiation of the replication of E1 DNA requires the chromosomal A product. In contrast two de-repressed transfer factors ( and 152) seem to determine a corresponding plasmid-specific factor. The C-product is necessary for the ordered initation of all plasmids studied. The addition of low concentrations of chloramphenicol leads to a relaxed replication of E1 DNA at the restrictive temperature in A-mutants, but not in C-mutants. 相似文献
14.
The initial membrane reaction in the biosynthesis of peptidoglycan is catalyzed by (MurNAc)-pentapeptide translocase (UDP-MurNAc-Ala-γ dGlu-Lys-dAla-dAla undecaprenyl phosphate phospho-MurN Acpentapeptide transferase). In addition to the transfer reaction, the enzyme catalyzes the exchange of [3H]uridine monophosphate with the uridine monophosphate moiety of UDP-MurN Ac-pentapeptide. Two distinct discontinuities are observed in the slopes of the Arrhenius plots of the exchange and transfer activities at 22 and 30°C for the enzyme from Staphylococcus aureus Copenhagen. Anisotropy measurements of perylene fluorescence and electron spin resonance measurements of derivatives of 12-and 16-ketostearic acid intercalated into membranes from this organism define the lower () and upper () boundaries of a phase transition. These values correlate with the discontinuities observed for the activity measurements. Thus, it is proposed that the physical state of the lipid micro-environment of phospho-MurN Ac-pentapeptide translocase has a significant effect on the catalytic activity of this enzyme. 相似文献
15.
The synthesis and characterization of - and -3,4-bis(4-hydroxyphenyl)-2-hexene (- and -pseudo-DES) and of -3,4-bis(4-hydroxyphenyl)-2-hexen-1-ol (-1-hydroxypseudo-DES) are described. These compounds are useful as probes in the study of hormone action. 相似文献
16.
The specific synthesis of F mRNA directed by the F gene carried on the specialized transducing bacteriophage F, performed , is described with the use of an S180 extract from a strain carrying R?. Synthesis of F mRNA is biphasic at approximately 7 minutes. The regulation of F mRNA synthesis by the specific arginine holorepressor present in an S180 extract prepared from a strain carrying the R+ allele is described. 相似文献
17.
18.
Robert D. Clark Russell E. MacDonald 《Biochemical and biophysical research communications》1981,102(1):545-553
We have prepared vesicles from cell envelope membranes of strains R1 and ET-15 which are able to synthesize ATP in response to illumination. This photophosphorylation is inhibited by dicyclohexylcarbodiimide (DCCD) and by phloretin. ATP synthesis in L vesicles from the R1 strain (which contain bacteriorhodopsin) is inhibited by the protonophore 1799 but not by valinomycin. In M vesicles from the R1 strain and in ET-15 vesicles (both contain halorhodopsin) photophosphorylation is inhibited by both 1799 and valinomycin. These data are consistent with the idea that light-driven ATP synthesis can be coupled to the electrochemical H+ gradient generated by bacteriorhodopsin or by halorhodopsin through the membrane potential component of protonmotive force. 相似文献
19.
Jerry M. Buysse Sunil Palchaudhuri 《Biochemical and biophysical research communications》1982,106(3):748-755
The minichromosome pWS6 was unstable in , K-12 but became stable upon transfer to ,. The instability of pWS6 was restored when pWS6 was brought back to ,, an observation consistent with the proposed phenomena of chromosomal incompatibility. 相似文献
20.
G. Sheir-Neiss R.V. Nardi M.A. Gealt N.R. Morris 《Biochemical and biophysical research communications》1976,69(2):285-290
[35S] labeled extracts of the fungus were copolymerized with purified porcine brain tubulin. The [35S] protein which copurified with porcine microtubules was found to be similar to [3H] chick tubulin when the two were coelectrophoresed on several polyacrylamide gel electrophoresis systems. These results strongly suggest the presence in of a tubulin-like protein. 相似文献