共查询到20条相似文献,搜索用时 15 毫秒
1.
P.N. Bandyopadhyay Maharani Chakravorty 《Biochemical and biophysical research communications》1976,71(2):644-650
Infection of with the mutant of bacteriophage P22 leads to a rapid and severe efflux of intracellular leucine. The superinfection exclusion () genes of P22 interfere with the function of gene, the product(s) of which is speculated to be an internal protein of phage P22. 相似文献
2.
Thiolutin resistant mutants of can not support the development of phage P22 at high temperature (40°C). Although normal amounts of phage DNA and lysozyme are synthesised, very few infectious particles are formed at higher temperature. The results indicate the involvement of host function in phage development. 相似文献
3.
Uracil-DNA glycosylase of is involved in repair of deaminated cytosine residues of DNA. Survivals of SPO2 phage after treatment with bisulfite and weak alkali are considerably higher in wild type strains than in mutants, which are deficient in the enzyme activity, whereas survivals of bisulfite/alkali-treated PBS1 phage in the two types of cells are essentially the same. The spontaneous mutation frequency of a mutant is three fold higher than is that of a wild type strain. 相似文献
4.
T4 bacteriophage mRNA for lysozyme was extracted from T4 phage infected cells, partially purified by column chromatography, and translated in a heterologous cell-free protein synthesizing system prepared from wheat germ. The translation product was confirmed by SDS polyacrylamide gel electrophoresis and enzymatic activity — bacteriolysis as tested with . The specific activity of the enzyme prepared was 660 U/mg. 相似文献
5.
《Insect Biochemistry》1991,21(7):795-801
The egt gene of the baculovirus Autographa californica nuclear polyhedrosis virus encodes an ecdysteroid UDP-glucosyltransferase. The glucoside formed by this enzyme using ecdysone and UDP-glucose as substrates has been purified and structurally characterized by nuclear magnetic resonance spectroscopy and by fast atom bombardment mass spectrometry. These studies have identified the conjugate as ecdysone . Substrate specificity studies have confirmed that ecdysteroids lacking a hydroxyl moiety at C-22 are not substrates for the enzyme. 相似文献
6.
Steven R. Jordan Carl O. Pabo Andrew K. Vershon Robert T. Sauer 《Journal of molecular biology》1985,185(2):445-446
Arc, a represser from Salmonella phage P22 has been crystallized from ammonium phosphate at pH 8.0. The crystals form in space group P212121 with . The crystals diffract to 2.2 Å resolution. 相似文献
7.
Giovanna Grimaldi John Guardiola 《Biochemical and biophysical research communications》1981,101(4):1233-1240
The mutation (obtained by phage mediated mutagenesis) affects the sensitivity to valine inhibition of the acetohydroxy acid synthase III isoenzyme of K-12, as shown by constructing multiple mutants containing the mutation and only one of the genes for the expression of the three acetohydroxy acid synthase isoenzymes, at once. The mutation is dominant. This suggests that the phenotype of mutation is not caused by inactivation of a gene concerned with the expression of the AHASIII enzyme, consequent to prophage insertion into that locus. 相似文献
8.
The synthesis of β-galactosidase (EC 3.2.1.23: β-D-galactoside galactohydrolase) in is repressed as a result of infection with single-stranded DNA phage ØX174. An mutant in ØX174 cistron A, which codes for two proteins, does not inhibit the enzyme synthesis while mutants in all other genes do cause repression. A mutant near the amino-terminal end of cistron A, which produces the small 35,000 molecular weight cistron A polypeptide, also inhibits the synthesis of β-galactosidase. Inhibition is also observed in an mutant which does not support the replication of replicative-form DNA. Exogenous nucleotide bases and cyclic 3′,5′-adenosine monophosphate (cyclic AMP) do not have any effect on the degree of repression. 相似文献
9.
, 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
10.
Identification of an Escherichia coli inner membrane polypeptide specified by a lambda-tonB transducing. 总被引:1,自引:0,他引:1
Analysis by polyacrylamide gel electrophoresis of the proteins coded by a λB transducing phage, after infection of UV-irradiated bacteria, revealed the presence of at least 7 new polypeptides. Three of these were identified as proteins of the operon whilst three others were deleted by a spontaneous mutation in the B region carried by the phage. A single polypeptide, molecular weight 40,000 was absent from a phage carrying a proflavine induced mutation in B. We conclude that this protein, which was localised in the inner membrane by sarkosyl fractionation of the envelope, is the product. 相似文献
11.
Paul K. Tomich G. Robert Greenberg 《Biochemical and biophysical research communications》1973,50(4):1032-1038
Infection by , a temperature-sensitive mutant of gene 42 of phage T4, the structural gene for dCMP hydroxymethylase, previously was shown not to form T4 DNA at nonpermissive temperatures. Yet the enzyme activity was found in extracts. Since inactivation of the enzyme was not reversible, we have examined acid-soluble extracts of cells infected at nonpermissive temperature by for 5-hydroxymethyldCMP in order to determine whether the enzyme functioned . A double mutant of and (5-hydroxymethyldCMP kinase) did not form the nucleotide at nonpermissive temperature, but the control, , formed large quantities. From these results and previous temperature-shift studies it is suggested that the enzyme is normally activated to function between 5 and 8 minutes after infection. 相似文献
12.
Beverly A. Teicher Mikio Shikita Paul Talalay 《Biochemical and biophysical research communications》1978,83(4):1436-1441
A heat-stable protein activator from bovine adrenal cortex mitochondria stimulates the conversion of cholesterol to pregnenolone in crude extracts of adrenal mitochondria, and resembles in some of its properties, the sterol carrier protein of liver (Kan . . . . . , 423–429, 1972). We have shown that activator preparations also stimulate highly purified adrenal enzyme preparations comprising four components: cytochrome P-450 specific for side chain cleavage, adrenodoxin, adrenodoxin reductase, and an NADPH-generating system. Furthermore, this activator stimulates the conversion not only of cholesterol, but also of (20S)-20-hydroxycholesterol, (22)-22-hydroxycholesterol, and (20, 22)-20,22-dihydroxycholesterol to pregnenolone. Our findings provide additional evidence that the steroid-activator complexes are the substrates for the side chain cleavage enzyme and that the monohydroxy and dihydroxycholesterols are true intermediates in the conversion of cholesterol to pregnenolone by bovine adrenal cortex mitochondria. 相似文献
13.
Giant T4 bacteriophage were found by Doermann et al. (1973a) with point mutants in gene 23 and by Cummings et al. (1973) after l-canavanine induction followed by an arginine chase. We now find T4 giant phage with 14 out of 15 tested temperature-sensitive mutants in gene 24 grown at intermediate temperatures between 33 °C and 37 °C.For one of these mutants, T4,24(tsB86), we found that (a) the optimum temperature for giant phage production is 34.8 °C, (b) the head-length distribution peaks sharply between 10 and 12 normal T4 phage head lengths, (c) about 75% of our giant phage have two tails, (d) the buoyant density in CsCl is greater than that of normal phage, (e) they are infectious and show an increased u.v. resistance, (f) their sodium dodecyl sulphate gel electrophoresis pattern is qualitatively similar to that of normal T4 phage, although the relative intensities of some of the bands are different, showing for example, a decreased 2 ratio, (g) optical diffraction and filtering of the flattened cylindrical part of the giant heads show a p6 surface net with a lattice constant of approximately 130 Å, a unique ratio of and a capsomer morphology of the type 1 + 6 + 6.Mixed infections with T4 wild type and T4.24(amN65) also yield giant phage. These are produced in highest amounts with a multiplicity of infection ratio of 5:5; no giants are observed at ratios of 1:9 or 9:1, suggesting that their formation may be caused by a dosage effect of P24. 相似文献
14.
The alpha-adrenergic blocking agent, yohimbine, prevented the production of the morphine Straub tail reaction in mice, although on a mg dose basis it was only about as potent as the narcotic antagonist naltrexone by subcutaneous injection. Likewise, yohimbine prevented the potentiation of the morphine Straub tail reaction by amphetamine, being about as active as naltrexone. Preliminary studies with another alpha-adrenergic blocking agent, phentolamine, indicated that it also inhibited the production of the Straub tail reaction by morphine, although it appeared to be somewhat weaker than yohimbine in this respect. These results suggest the involvement of alpha-adrenergic mechanisms in the production of the morphine Straub tail reaction and in the potentiation of the morphine Straub tail reaction by amphetamine. 相似文献
15.
Adsorption of bacteriophages specific for Pseudomonas aeruginosa R factors RP1 and R1822 总被引:12,自引:0,他引:12
D E Bradley 《Biochemical and biophysical research communications》1974,57(3):893-900
Short, thick pili were found by electron microscopy on bacteria carrying the P group drug resistance plasmids RP1 and R1822. The R1822-specific phage PRR1 was seen to adsorb to the bases of the pili. Three RP1-specific phages, one filamentous (Pf3), and two with very thick capsids (PR3, PR4), were seen to attach all around the surface of cells, and were thought to be somatic, since pilus phages appear to be strictly polar on this species. PR3 and PR4 also lysed a strain of containing an N group plasmid, suggesting a relationship between the N and P group plasmids. 相似文献
16.
Ultraviolet light-induced recombination 总被引:2,自引:0,他引:2
R B Helling 《Biochemical and biophysical research communications》1973,55(3):752-757
Stimulation of transduction in by ultraviolet irradiation of the transducing phage P1 requires the nuclease but not the product or DNA polymerase I. It is hypothesized that the first step in “normal” recombination can be bypassed by any procedure generating single-stranded ends of DNA (as, for example, by nuclease activity). 相似文献
17.
Crystallization of resolvase, a repressor that also catalyzes site-specific DNA recombination 总被引:2,自引:0,他引:2
P C Weber D L Ollis W R Bebrin S S Abdel-Meguid T A Steitz 《Journal of molecular biology》1982,157(4):689-690
Resolvase, a site-specific recombination enzyme involved in transposition of movable elements of DNA, has been crystallized. The space group is P6222 (or enantiomorph ), with a monomer in the crystallographic asymmetric unit. 相似文献
18.
P P Hipps M R Eveland M H Laird W R Sherman 《Biochemical and biophysical research communications》1976,68(4):1133-1138
-Inositol:NAD(P)+ oxidoreductase (-inositol oxidoreductase) has been identified in bovine brain. This enzyme elutes from DEAE cellulose with 0.3 M KCl in 50 mM Tris buffer, pH 7.5. Using NADH as cofactor -inosose-2 is reduced selectively to -inositol. With NADPH the enzyme forms both -inositol and -inositol, however, at a lower rate. The enzyme was chromatographed on G-100 Sephadex and found to have an apparent molecular weight of 74,000. This enzyme differs in DEAE binding, molecular weight and cofactor specificity from the previously described -inositol oxidoreductase which utilizes NADPH exclusively to produce 3 fold more -inositol than -inositol. 相似文献
19.
Template specificity changes of DNA-dependent RNA polymerase in B. subtilis during sporulation 总被引:4,自引:0,他引:4
Previous work has indicated that loss of ability of DNA dependent RNA polymerase, from stationary phase cultures of , to transcribe phage øe DNA was a for sporulation. To ascertain if this change in template specificity was sporulation-specific, we repeated these experiments using a defined sporulation medium. The changes observed previously did not occur in the defined medium although sporulation was normal. The ability of the enzyme to transcribe other DNA templates was also examined. Similar studies were carried out using a polymerase from a rifamycin-resistant, sporulation conditional mutant. The significance of these findings with regard to the regulation of sporulation in is discussed. 相似文献