Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two antiviral pyrimidine derivatives, known to partially inhibit RNA dependent RNA polymerase of Mengo virus in a cell-free system, were found to bind with biopolymers. The antiviral compounds, at concentration of 100 and 50 muM and lower, showed complete inhibition of the virus-induced cytopathic effect and plaque reduction. Both compounds showed fluorescence emission with a maximum at about 500 nm under the influence of UV light of the wavelength of 366 nm. The fluorescence intensity increased upon addition of aqueous solutions of DNA, RNA and human serum albumin. This indicates that both compounds are capable of binding with nucleic acids and proteins. Based on the binding experiments alone it cannot be decided whether interference with nucleic acid template activity, enzyme function, or both are responsible for the virostatic action. Irradiation with violet light considerably enhances the virostatic activity, a fact that may be caused by photodynamic processes.
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PMID:Antiviral pyrimidine derivatives: binding with biopolymers and photosensitization. 2 7

The kinetics of reaction of 4-chloro-7-nitrobenzofurazan with thiol groups at pH values above 5 cannot be accounted for solely on the basis of formation of a single product, the 4-thio derivative. Spectroscopic observations indicate that, in addition to the 4-thio derivative, at least two other products are formed. One of these, referred to as P1, is most likely a reversible complex of thiol compound and 4-chloro-7-nitrobenzofurazan of the Meisenheimer type. The other product, P2, which forms primarily when thiol compound is in a large excess, does not appear to result from direct reaction of thiol group and 4-chloro-7-nitrobenzofurazan, but may be a reaction of product P1 and thiol compound. The coloured product, P2, will react further with proteins, such as bovine serum albumin and Escherichia coli RNA polymerase. This reaction irreversibly destroys the catalytic activity of RNA polymerase. The implications of these observations for utilization of 4-chloro-7-nitrobenzofurazan as a protein-modifying agent are discussed.
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PMID:Anomalous reaction of 4-chloro-7-nitrobenzofurazan with thiol compounds. 43 40

We have developed a system for the in vitro transcription of specific genes in rooster liver chromatin by endogenous RNA polymerase II that maintains the specificity of transcription in vivo. Radioactive transcripts synthesized in vitro were identified and quantitated by hybridization to a vast excess of cloned cDNA. The cDNA preparations employed corresponded to vitellogenin mRNA, the synthesis of which is responsive to estrogen stimulation in vivo, and chicken serum albumin mRNA, the synthesis of which is not significantly affected by estrogen stimulation in vivo. Comparing the pattern of transcription of the albumin and vitellogenin genes in chromatin from the liver of the normal rooster with the pattern in chromatin from the liver of the estrogen-stimulated rooster, we found that prior estrogen treatment of the rooster is attended by a slight decrease in the differential rate of transcription of the albumin gene and approximately a 10-fold increase in the differential rate of transcription of the vitellogenin gene. Because this pattern of transcription reflects the estrogen-induced changes in transcription observed in vivo, chromatin preparations from the livers of normal and estrogen-stimulated roosters can be used to investigate regulation of specific gene transcription at the molecular level in vitro.
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PMID:Specific transcription in chicken liver chromatin by endogenous RNA polymerase II. Comparison of an estrogen-inducible gene with a constitutively expressed gene. 48 77

Spermatogenesis is a complex developmental process which sequentially generates several different germ cell types. These cell types from rainbow trout (Salmo gairdnerii) testis were separated by sedimentation in serum albumin gradients and characterized on the basis of their physical properties, chronological appearance, and protein synthesis. The rate of RNA synthesis, the types of RNA made, and the RNA polymerase activities present were determined for each cell type. The rate of RNA synthesis decreased from a high level in spermatogonia and spermatocytes to a low level in early spermatids and was absent in late spermatids and mature spermatozoa. Newly synthesized RNA in spermatogonia and spermatocytes consisted of a variety of molecular weight species, including 18 S and 28 S ribosomal RNAs. The synthesis of high molecular weight RNAs, especially ribosomal RNAs, decreased drastically in early spermatids, leading to the synthesis of only small molecular weight RNAs. RNA polymerase I and II were present in all cell types but the activities of both showed large decreases between spermatocytes and middle spermatids. Both RNA polymerase activities were almost absent from spermatozoa. The activities of RNA polymerase I and II from unfractionated testis cells at different stages of hormone-induced spermatogenesis were quantitated by fractionation of the solubilized extract on DEAE-cellulose. Both polymerases showed major decreases in activity which began near the chronological mid-point of development. For polymerase I the decrease in activity was over 400 fold, for polymerase II over 200 fold. The number of RNA polymerase II molecules per testis cell, quantitated by the binding of [3H]amanitin to cell extracts, also decreased markedly during spermatogenesis. The reduction in polymerase II activity was accompanied by a parallel 200-fold decrease in[3H]amanitin binding. The reduction in polymerase activity appears, therefore, to be due to an actual reduction in the cellular content of RNA polymerase II molecules. These results suggest that transcription in maturing testes is regulated, at least in part, by the concentrations of the RNA polymerases.
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PMID:RNA synthesis and RNA polymerase activities in germ cells of developing rainbow trout testis. 51 81

Partially purified rat liver RNA polymerase I chromatographed on ribosomal RNA-Sepharose loses most (96%) of its activity assayed on native calf-thymus DNA templates, but loses little (8%) of its activity assayed on poly(deoxycytidylic acid) template. Polymerase I is not stimulated by polymerase II protein factor, or by bovine serum albumin. However, it is stimulated by histones, polylysine, and spermine. Addition of a protein fraction eluted by high ionic strength from the rRNA-Sepharose also restores activity on native calf-thymus DNA. Further purification yields a fraction containing two proteins of 11 000 and 12 000 molecular weight. Both proteins are distinct from histones by electrophoresis in sodium dodecyl sulfate and in acid urea. Both proteins are basic, insensitive to heat, bind to DNA, and stimulate polymerase I activity. The degree of stimulation of polymerase I is dependent upon both the enzyme/DNA and the factor/DNA ratio. The protein factors also stimulate polymerase II activity about half as effectively as polymerase I.
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PMID:A protein cofactor that stimulates the activity of DNA-dependent RNA polymerase I on double-stranded DNA. 85 26

Rhodium(II) acetate, propionate, and butyrate showed a considerable variation in their antitumor activity against Ehrlich ascites tumor cells in mice, with the butyrate complex being the most active. The three complexes markedly inhibited DNA synthesis of Ehrlich ascites tumor cells in vivo. Rhodium (II) butyrate was the most potent inhibitor followed by the propionate complex. One hour after administration, rhodium(II) propionate and butyrate induce more uridine-5-3H incorporation into RNA than is seen in the controls. Equilibrium dialysis studied showed that rhodium(II) acetate-1-14C binds to single stranded DNA, poly-A, ribonuclease A, and bovine serum albumin but not to highly polymerized native calf thymus DNA, poly-G, or poly-C. In these cases binding occurred at the two axial positions of rhodium(II) acetate to a nitrogen donor in the ligands. The formation constants of the rhodium(II) acetate and propionate complexes with 5'-adenosine monophosphate were determined. The rhodium(II) propionate complex was more stable. Sedimentation and viscosity measurements of poly-A and poly-A/rhodium(II) acetate complexes indicate a high degree of intramolecular crosslinking in the rhodium(II) acetate/poly-A complex. The rhodium(II) carboxylate complexes were also found to be potent inhibitors of purified DNA polymerase I and RNA polymerase from Escherichia coli.
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PMID:Interaction of Rhodium(II) carboxylates with molecules of biologic importance. 110 39

Factors affecting the inhibition of RNA polymerase II from rat liver by the O-n-octyloxime of 3-formylrifamycin SV (AF/013) were investigated. Using either native or denatured calf-thymus DNA as template, almost complete inhibition of RNA polymerase II was observed when AF/013 was added directly to the enzyme. Considerable resistance to AF/013 was observed when RNA polymerase II was preincubated with denatured DNA at either 0 or 37 degrees. However, under similar conditions, no resistance was observed when enzyme was preincubated with native DNA. Only when AF/013 was added to the ongoing reaction using native DNA did a resistance to AF/013 occur. The inhibition of RNA polymerase II by AF/013 was competitive with respect to all four nucleoside triphosphate substrates. The inhibition by AF/013 remaining after enzyme-DNA complex formation also appeared competitive with nucleoside triphosphate levels. The effect of exogenous protein (bovine serum albumin, BSA) on the inhibition of RNA polymerase II was also investigated. BSA reduced the extent of inhibition by AF/013, but did not alter the competitive nature of inhibition. Concurrently, the inhibition of highly purified nuclear poly(A) polymerase from rat liver, a template independent enzyme which incorporates AMP in a chain elongation reaction, was examined. As in the case of RNA polymerase, poly(A) polymerase was inhibited by AF/013 in a manner competitive with the nucleoside triphosphate substrate. The competitive nature of inhibition of RNA polymerase by AF/013 with respect to all four nucleoside triphosphate substrates, before and after enzyme-DNA complex formation, as well as the competitive nature of inhibition of poly(A) polymerase with respect to ATP tend to indicate that the major effect of AF/013 on RNA polymerase II is at the level of the substrate binding as opposed to a specific inhibition of initiation.
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PMID:Mechanism of inhibition of RNA polymerase II and poly(adenylic acid) polymerase by the O-n-octyloxime of 3-formylrifamycin SV. 116 99

Nuclei have been prepared from the oviduct of the adult laying hen which are capable of synthesizing large amounts of RNA for long periods of time. The time course of RNA synthesis is linear through 3 h of incubation after an initial burst of activity and is inhibited 60-70% by alpha-amanitin. Maximum synthetic activity requires the presence of serum albumin to stabilize the nuclei, high concentrations of the four ribonucleoside triphosphates, and an incubation temperature of 25 degrees C for continued linear synthesis beyond 30 min. The RNA synthesized in vitro is predominantly 10-20 S with a small proportion of higher molecular weight product. Much of the 10-20S RNA is probably transcribed by RNA polymerase II and is of a size comparable to ovalbumin mRNA. A fraction of this RNA appears to contain poly(A) sequences suggesting that there is some processing of the newly synthesized RNA. These nuclei may provide a useful system for studying the control of the transcription and maturation of ovalbumin mRNA in vitro.
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PMID:RNA synthesis in isolated hen oviduct nuclei. 124 36

Reductive alkylation mediated by cyanoborohydride is an attractive approach to the conjugation of small molecules, such as drugs, to proteins. This reaction is specific for protein amino groups and can be conducted under mild conditions with little risk of protein polymerization. However, the lability of the aldehyde function that is needed in such reactions presents a difficulty. We have investigated the use of derivatives of D-galactosamine and D-glucosamine in reductive alkylation, since these sugars contain aldehyde groups that are inherently protected and that may be readily linked to other molecules through their amino groups. The amino groups of these sugars were acylated with N-4-nitro-benzoylglycylglycine. Studies of the reductive coupling of the resultant adducts to bovine serum albumin revealed that conjugation to albumin is strongly dependent on cyanoborohydride, is much faster in the presence of borate, and shows a marked increase in rate between pH 7.0 and 9.0. In the presence of borate, the glucosamine derivative coupled much more rapidly than did the galactosamine derivative. The aryl nitro group of the glucosamine adduct was selectively reduced to an amine, diazotized, and reacted with alpha-amanitin to form an azo compound. This azo derivative was reductively coupled to form conjugates that inhibit calf thymus RNA polymerase II.
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PMID:Conjugation of N-acylated amino sugars to protein by reductive alkylation using sodium cyanoborohydride: application to an azo derivative of alpha-amanitin. 179 55

We have examined the sensitivity of various cellular and viral DNA polymerases to Suramin, an antitrypanosomal drug, which has been reported to exhibit antireverse transcriptase activity. We find that Suramin is a nonspecific inhibitor of all the viral and cellular DNA polymerases, including terminal deoxynucleotidyl transferase, and that the inhibition is most readily reversed by the addition of serum albumin. The drug appears to bind to all the enzyme proteins with no apparent selectivity. Binding of Suramin to enzyme has been found to result in the loss of both substrate and templateprimer binding abilities of various enzymes, confirming the nonspecific nature of protein-Suramin interaction.
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PMID:Observations on the suramin-mediated inhibition of cellular and viral DNA polymerases. 240 17


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