Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A single injection of the carcinogen 3'-methyl-4-dimethylaminoazobenzene (3'MDAB) or its non-carcinogen analogue 2-methyl-4-dimethylaminoazobenzene (2-MDAB) 300 mg/1000 g body weight led to the increase in the RNA-synthetic capacity of liver cell nuclei in vitro. No differences were found in the ribonuclease activity; in the template activity of DNA and DNP with E. coli RNA-polymerase, and in the melting temperature of DNA and DNP in the presence of 3'MDAB and in the control. The apparent value or Km of the RNA synthesis reaction are equal both for the control animals and those treated with 3'MDAB, but Vmax is lower in the control. It is suggested that the increase of RNA synthetic capacity of the nuclei of rat liver cells, found in vitro at early stages of the carcinogen (3'MDAB) action, should be regarded as the manifestation of its toxic effect and is proposed to be due to the increase of the concentration of RNA-polymerase which is capable to catalyse the RNA synthesis in nuclei.
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PMID:[Changes in RNA synthesis at early stages of aminoazocancerogenesis]. 81 58

Polysome and ribosome preparations from normal rat liver and from a series of transplantable rat hepatomas of different growth rates were compared. All the hepatomas had a significantly higher percentage of RNA in a polysome preparation than did the normal liver, and the polysome preparations from the tumors, with the exception of the Dunning hepatoma which has a high lipid content, gave a greater yield of RNA and protein per gram of wet tissue than the liver did. Heavier polysomes were considerably less prevalent in the tumors than in the liver, and the tumors contained a larger proportion of monomer and dimer ribosomes than the liver did. Evidence is presented that the increased monomer and dimer ribosome population of the hepatomas studied is not an artifact of preparation, but represents the true intracellular distribution. Ribosomes from normal liver and Morris 5123-D hepatoma were readily dissociated by 20 min' treatment with 1.0 mM EDTA, but ribosomes from the Dunning, Novikoff ascites, and McCoy MDAB hepatomas were little affected by such treatment. With higher concentrations of EDTA, the ribosomes from the Novikoff ascites and McCoy MDAB hepatomas broke down and did not form specific subunits as did ribosomes from liver and the Morris 5123-D hepatoma but rather gave rise to a variety of small degradation products. This behavior is ascribed to a higher RNase content of the Novikoff and McCoy MDAB hepatomas. Dunning hepatoma ribosomes were resistant to 4 mM EDTA.
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PMID:Studies on the function of intracellular ribonucleases. IV. Some observations on the properties of ribosomes and polysomes from rat liver and hepatomas. 428 63

The RNase activity and properties of ribosome and polysome preparations from normal rat liver and some hepatomas have been examined. Polysome and ribosome preparations from the Novikoff, McCoy MDAB, and Dunning hepatomas had considerably higher specific RNase activity than corresponding preparations from normal rat liver, Novikoff ascites, or Morris 5123 hepatomas. The optimum pH of the RNase was approximately 8.5 for all samples tested, and the samples showed no evidence of latent RNase activity when treated with 3 M sodium chloride, EDTA, urea, or p-chloromercuribenzenesulfonic acid. The RNase activity appeared to be associated principally with breakdown products and/or subunits smaller than 80S. In the presence of Mg(++) ions, subunits could reaggregate to form monomer ribosomes indistinguishable from the natural products, but some of the reassociated ribosomes could contain RNase activity which had been bound to the smaller particles. Similar results were obtained with spermine. In the hepatomas, evidence was obtained for the preexistence of considerable amounts of the smaller, RNase-containing subunits in the cell. When a small amount of crystalline bovine pancreatic RNase was added to partly dissociated ribosomes, the RNase was found only in association with the smaller subunits, and little or no enzyme was taken up by ribosomes or polysomes. The results have led to the conclusion that RNase is not a normal constituent of the ribosome or polysome, but that RNase may become associated with these particulates if dissociation and reassociation take place. Some implications of these findings for the stability of messenger RNA and for the mechanism of its breakdown are discussed.
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PMID:Studies on the function of intracellular ribonucleases. V. Ribonuclease activity in ribosomes and polysomes prepared from rat liver and hepatomas. 428 64