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Results for “Polyribonucleotides”

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At least 847 records · Page 47Linked to original sources
PubMed1985

Effect of deoxyribopolymers and ribopolymers on the sensitivity of the cyclic-AMP receptor protein of Escherichia coli to proteolytic attack.

The cAMP receptor protein (CRP) is an allosteric protein in which binding of cAMP effects a conformational change with a consequent increased affinity for DNA. Unliganded CRP is relatively resistant to attack by a variety of proteases (trypsin, subtilisin, Staphylococcus aureus V8 protease, clostripain, chymotrypsin) which cleave cAMP-CRP, producing N-terminal cores which have lost DNA binding activity. Binding of double-stranded deoxyribopolynucleotides and calf thymus DNA by cAMP-CRP confers protection against attack by trypsin, subtilisin, S. aureus V8 protease, and clostripain. Such cAMP-CRP-DNA complexes remain sensitive to attack by chymotrypsin. Of the single-stranded deoxy- and ribopolynucleotides tested, only r(I)n and r(A)n gave significant protection against attack by these proteases (with the exception of chymotrypsin). Since the cutting sites for trypsin (Lys 130) and subtilisin (Leu 116) are not part of the C-terminal DNA binding domain, it would appear that binding of DNA may confer conformational changes on other regions of cAMP-CRP.

Bacterial Proteins↗
PubMed1985

Extensive synthesis of poly[r(G-C)] using Escherichia coli RNA polymerase.

Conditions have been found that allow for extensive synthesis of poly[r(G-C)] using Escherichia coli RNA polymerase with a poly[d(I-C) X poly[d(I-C)] template. The extensive synthesis, in which many copies of the template were produced by the enzyme, continued for 24 h. Repeated addition of the template was necessary for synthesis to continue, as the poly[r(G-C)] appeared to be binding to the template, inhibiting transcription by the polymerase. Four hundred ODU, or 20 mg of the poly[r(G-C)] has been prepared using 0.3 mg of protein.

DNA-Directed RNA Polymerases↗
PubMed1987

Activation of deoxycholic acid by the lipid peroxy radical and its covalent binding to nucleic acids.

Deoxycholic acid, a colon tumor promoter, was found to bind covalently to DNA and RNA in the presence of methyl linoleate hydroperoxide and ferrous ion. This binding was shown to occur specifically with guanine residues and its covalent nature was demonstrated by analysis of hydrolysates of nucleic acid adducts. These findings are discussed in connection with the increased risk of colon cancer associated with a high fat and meat diet.

DNA↗
PubMed1990

Inhibition of adenylate cyclase by polyadenylate.

The effects of ribo- and deoxyribonucleic acids on the activity of detergent-dispersed adenylate cyclases from rat and bovine brain were examined. Mn2+ (10 mM)-activated adenylate cyclase was inhibited by micromolar concentrations of poly(A) (IC50 congruent to 0.45 microM). This inhibition was directly due to poly(A) and was not mediated by: (a) protein contamination of the poly(A) preparation, (b) metal chelation, (c) formation of an acid-soluble inhibitor of adenylate cyclase, (d) effects on the specific activity of [alpha-32P]ATP, (e) competition with MnATP for binding to adenylate cyclase, or (f) diversion of substrate to an alternate polymerase reaction. Inhibition of adenylate cyclase by poly(A) was on the enzyme's catalytic unit, as purified preparations of the enzyme from bovine brain were inhibited by poly(A). This inhibition by poly(A) was not likely mediated via the enzyme's "P"-site, through which activated forms of the enzyme are selectively inhibited by specific adenosine phosphates. In contrast with inhibition by the "P"-site agonist 3' AMP, inhibition of adenylate cyclase by poly(A) was slow in onset and was not reversible by dilution and showed a different metal-dependence. Inhibition of adenylate cyclase was relatively specific for poly(A) as poly(U) caused less than 50% inhibition and deoxyribonucleic acids had no effect. The potency and specificity of the inhibition of adenylate cyclase by poly(A) imply a biochemically interesting interaction that is possibly also of physiological significance.

Adenylyl Cyclase Inhibitors↗
PubMed1974

Gel electrophoretic analysis of poly(riboadenylic acid).

It is shown that molecular weights and molecular-weight distributions of poly(rA), and by implication other single-stranded polynucleotides, and synthetic and natural polyelectrolytes in general, can be determined by electrophoresis in polyacrylamide gels. It is shown that fractions of very narrow molecular-weight distribution can be obtained by preparative electrophoresis of polydisperse samples. Molecular-weight calibrations based on sedimentation coefficients of such fractions are given, and in aqueous systems do not coincide with calibrations for partially base-paired RNA species. Poly(rU) fractions fall on the same calibration as poly(rA). Relations between mobilities, relative to standard markers, and molecular weight for poly(rA) over a wide range of molecular weights are given, which allow rapid molecular-weight determination on poly(rA) samples, such as the segments found in many types of messenger RNA.

Electrophoresis, Polyacrylamide Gel↗
PubMed1974

Escherichia coli initiation factor IF3 binding to AUG and AUG-containing single strands and hairpin loops, and nonspecific binding to polymers.

Nitrocellulose filter binding and equilibrium dialysis detected the binding of Escherichia coli initiation factor IF3 to AUG, An UGUm single strands and hairpin loops, poly(A,U,G), poly(U), and f2 RNA. No binding was detected for GUA, A8 U, or the hairpin loop A5 GC5 U5. AUG-specific binding, per nucleotide, is strong; nonspecific binding, per nucleotide, is weak.

Binding, Competitive↗