共查询到20条相似文献,搜索用时 15 毫秒
1.
Peter B. Anzeveno 《Prostaglandins & other lipid mediators》1978,16(1):79-83
Stereosecific synthesis of -hydrindanone , a bicyclic analog of prostaglandin E1, the -hydrindane β-keto ester , is described. When tested in the guinea pig, exhibited no effects on blood pressure and no broncho-constriction or dilation activity. Additionally, failed to inhibit both ADP . 相似文献
2.
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
3.
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
4.
Robert Carey Johnson 《Biochemical and biophysical research communications》1976,70(3):791-796
Gaps in daughter-strand deoxyribonucleic acid (DNA) synthesized after exposure of wild-type to ultraviolet light are filled during reincubation. In this study the , and gene products have been examined for their role in postreplication repair. These gene products are unique in their specific control of certain types of DNA synthesis: initiation of rounds of replication and chain propagation. Initiation of rounds of replication is not essential to gap filling; however, chain propagation by short DNA piece initiation appears to be essential for gap filling. 相似文献
5.
Bernard J.R. Philogène 《Journal of insect physiology》1975,21(7):1415-1417
Subjecting larvae of Hypocrita jacobaeae to temperatures of 21 and 28°C and photoperiods of , , , and does not interfere with the phenomenon of diapause. The last larval instar is particularly affected by the higher temperature. Effects include numerous deaths, a high proportion of ill-formed pupae, and failure of adults to emerge properly from the pupal case. The significance of these findings is discussed. 相似文献
6.
, 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
7.
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
8.
Showdomycin inhibited pig brain ( with pseudo first-order kinetics. The rate of inhibition by showdomycin was examined in the presence of 16 combinations of four ligands, i.e., Na+, K+, Mg2+ and ATP, and was found to depend on the ligands added. Combinations of ligands were divided into five groups in terms of the magnitude of the rate constant; in the order of decreasing rate constants these were: (1), (2) , , and none, (3) , and , (4) and , , , and ATP. The highest rate was obtained in the presence of Na+, Mg2+ and ATP. The apparent concentrations of Na+, Mg2+ and ATP for half-maximum stimulation of inhibition () were 3 mM, 0.13 mM and 4μM, respectively. The rate was unchanged upon further increase in Na+ concentration from 140 to 1000 mM. The rates of inhibition could be explained on the basis of the enzyme forms present, including E1, E2, ES, E1-P and E2-P, i.e., E2 has higher reactivity with showdomycin than E1, while E2-P has almost the same reactivity as E1-P. We conclude that the reaction of ( proceeds via at least four kinds of enzyme form (E1, E2, E1 · nucleotide and EP), which all have different conformations. 相似文献
9.
John C. Sih Roy A. Johnson Eldon G. Nidy David R. Graber 《Prostaglandins & other lipid mediators》1978,15(3):409-421
We wish to report here the syntheses of (5, 6)-5-hydroxy-, (5, 6)-5-hydroxy-, (5, 6)-5-hydroxy-, and (5, 6)-5-hydroxy-PGI1 and their methyl ester derivatives. Treatment of (5, 6)-5-epoxy- and (5, 6)-5-epoxy-PFG1α methyl esters with acid washed silica gel afforded (5, 6)-5-hydroxy- and (5, 6)-5-hydroxy-PGI1 methyl esters; correspondingly, silica promoted cyclization of (5, 6)-epoxy- and (5, 6)-5-epoxy- PGF1 methyl esters yielded (5, 6)-5-hydroxy- and (5, 6)-5-hydroxy- PGI1 methyl esters. Alternatively, the 5-hydroxyl group was introduced into the PGI1 skeleton reaction of the 5-mercuric halides with sodium borohydride in the presence of oxygen. Stereochemical assignments were based on their mode of synthesis and 1H nmr shift differences. 相似文献
10.
Claudia Moore Merle L. Blank Ten-Ching Lee B. Benjamin Claude Piantadosi Fred Snyder 《Chemistry and physics of lipids》1978,21(3):175-178
In previous studies on the modification of polar head groups of membrane phospholipids with the unnatural base analog, , we reported an unidentified phospholipid in addition to in the various membrane fractions of rat liver. The structure of this phospholipid has now been identified as by nuclear magnetic resonance spectroscopy, and by chromatographic and enzymic analysis. In addition, we found that when rats were injected intraperitoneally with the , 19% of teh liver microsomal phospholipid was . 相似文献
11.
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
12.
The fluorescence properties of chlorophyll and monomolecular films at the air-water interface were measured by a high sensitivity fluorophotometer using the photon-counting method. The fluorescence intensity of chlorophyll molecules in monomolecular films in the absence of any diluents did not decrease simply with the mean distance of chlorophyll molecules. Over the range of the mean distances from 27 to 21 Å, three fluorescence components (peaks at 685, 695 and 715 nm) of chlorophyll were observed. In the case of chlorophyll , two fluorescence components (peaks at 667 and 685 nm) were observed over the range of the mean distances from 34 to 24 Å. When the mean distance was 18 Å, the short wavelength component of chlorophyll disappeared, and only the long wavelength component was observed. 相似文献
13.
According to previous authors, cytochrome , when extracted from bovine liver by a detergent method, is called cytochrome . On the other hand, the protein obtained after trypsin action, which eliminates an hydrophobic peptide of about 54 residues, is called cytochrome .Fluorescence polarization of the dansyl phosphatidylethanolamine probe inserted into phospholipid vesicles is very senstive to the binding of proteins, and so is a useful method to study lipid-protein interactions.The chromophore mobility, , decreases markedly when dipalmitoyl phosphatidylcholine vesicles are incubated with cytochrome , whereas does not change for cytochrome and cytochrome . This can be interpreted as a strengthening of the bilayer, only due to the interaction of the hydrophobic peptide tail.Interaction of dipalmitoyl phosphatidylcholine vesicles with cytochrome occurs either below or above the melting temperature of the aliphatic chains (41 °C). Even for a high protein to lipid molar ratio (1 molecule of protein for 40 phospholipid molecules), the melting temperature is apparently unaffected.Phosphatidylserine and phosphatidylinositol do not interact at pH 7.7 with cytochrome , because electrostatic forces prevent formation of complexes. At low pH, the interaction with the protein occurs, but the binding is mainly of electrostatic nature. 相似文献
14.
Michael D.P. Boyle 《Biochemical and biophysical research communications》1981,103(3):856-862
Zinc sulphate in the range of 10?4 to 2×10?5 M prevents the binding of to antigen antibody complexes, and the initation of the cascade of events in the classical complement pathway leading to cell lysis. Other heavy metals, Co++, Cd++, Cu++, or Mn++ were without effect in this concentration range. Zinc was ineffective when added after was bound and failed to displace which was already bound to antigen antibody complexes. The ability of zinc to regulate the binding of the zymogen or activated form of to antigen-antibody complexes represents a new method of controlling the initiation of the classical complement pathway. 相似文献
15.
16.
David Scicchitano Anthony E. Pegg 《Biochemical and biophysical research communications》1982,109(3):995-1001
The demethylation of O6-methylguanine in double stranded DNA catalyzed by rat liver O6-methylguanine-DNA transmethylase was found to proceed much more rapidly when the DNA substrate was methylated to a high extent. When the content of O6-methylguanine in DNA was equal to 1 in 2000 guanines, the reaction was 90% complete within 2 min, but when the content was 1 in 500,000 it required 27 min at 37°C. These results suggest that the repair protein either moves along the DNA substrate or else has little selectivity for binding specifically to the sites containing O6-methylguanine rather than to the normal DNA. The repair of O6-methylguanine in rat liver occurred at rates comparable to those seen with the substrates alkylated to low extents and was virtually complete within 3 hours. These results provide strong evidence that this protein is the factor responsible for O6-methylguanine removal and explain the wide variation in time courses reported in the literature since substrates methylated to greatly different extents have been used for such experiments. 相似文献
17.
18.
M. Bard R.A. Woods J.M. Haslam 《Biochemical and biophysical research communications》1974,56(2):324-330
The , and mutants of yeast require an unsaturated fatty acid and methionine for growth and do not synthesise ergosterol. They have very similar sterol compositions and all accumulate lanosterol. The mutants lack cytochrome pigments and have negligible respiratory activity. Porphyrin intermediates alleviate the lipid requirement of and and restore respiratory competence. It is concluded that the primary defects in these mutants are lesions in porphyrin biosynthesis. 相似文献
19.
F. Malpartida M. Zalacaín A. Jiménez J. Davies 《Biochemical and biophysical research communications》1983,117(1):6-12
The gene encoding the phosphotransferase enzyme that modifies hygromycin B in its producing organism , has been cloned in the vector pIJ41. Two plasmids, pFM4 and pFM6, containing 2.1 and 19.6 kb inserts of DNA, respectively, which express the modifying enzyme, have been isolated. A 3.1 kb PstI restriction fragment from pFM4 was inserted in the vector pIJ350 and the resulting plasmids, pMZ11.1 and pMZ11.2, express the hygromycin B-resistance phenotype. The utility of this dominant marker for cloning experiments is discussed in the text. 相似文献
20.
(1) A quantitative study has been made of the binding of ouabain to the ( in homogenates prepared from brain tissue of the hawk moth, Manduca sexta. The results have been compared to those obtained in bovine brain microsomes. (2) The insect brain ( will bind ouabain either in the presence of Mg2+ and Pi, (‘Mg2+, Pi’ conditions) or in the presence of Na+, Mg2+, and an adenine nucleotide (‘nucleotide’ conditions) as is the case for the bovine brain (. The binding conditions did not alter the total number of receptor sites measured at high ouabain concentrations in either tissue. (3) Potassium ion decreases the affinity (increases the ) of ouabain to the M. sexta brain ( under both binding conditions. However, ouabain binding is more sensitive to K+ inhibition under the nucleotide conditions. In bovine brain ouabain binding is equally sensitive to K+ inhibition under the both conditions. (4) The enzyme-ouabain complex has a rate of dissociation that is 10-fold faster in the M. sexta preparation than in the bovine brain preparation. Because of this, the M. sexta ( has a higher for ouabain binding and is less sensitive to inhibition by ouabain than the bovine brain enzyme. (5) This data supports the hypothesis that two different conformational states of the M. sexta ( can bind ouabain. 相似文献