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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ppp(A2'p)nA-dependent endoribonucleases from a number of different mammalian sources have been investigated. The enzyme from reticulocyte lysates shows optimal activity of 50-150 mM KCl and requires the presence of Mg2+. Whilst the enzyme is inactivated after passage of reticulocyte lysates through Sephadex columns in the absence of ATP, it retains full activity provided ATP is included in the column buffer. The activity of the partially purified nuclease was unaffected by the addition of reticulocyte RNase inhibitor, which, in contrast, effectively inhibited other endogenous endonucleases. The ppp(A2'p)nA-dependent Rnase co-purified with a ppp(A2'p)nA-binding protein and with a protein which could be specifically covalently labelled with an oxidised radioactive analogue of ppp(A2'p)nA. This covalent labelling could be carried out either with the partially purified RNase or in crude extracts from rabbit reticulocytes, mouse Krebs and Ehrlich ascites tumour cells and human lymphoblastoid (Daudi) or HeLa cells. In each case the affinity labelled protein migrated to a position corresponding to a apparent molecular weight of about 85 000 on electrophoresis on dodecylsulphate/polyacrylamide gels. In all cases labelling could be prevented by the addition of an excess of unlabelled ppp(A2'p)nA but not, for example, by a similar excess of the biologically inactive dimer ppp(A2'p)'A. It is concluded that the RNase and ppp(A2'p)nA binding activities are likely to reside in the same molecule.
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PMID:Affinity labelling and characterization of the ppp(A2'p)nA-dependent endoribonuclease from different mammalian sources. 628 2

Several investigators have failed to confirm any specificity of elevated serum ribonuclease (RNase) in the diagnosis of pancreatic cancer. Although RNase had been known to be present in two forms, free and inhibitor-bound, in various tissues of the rat, little was known about it in the human pancreas. The object of this report was to explore the presence of RNase inhibitor in the human pancreas through the assay of both active (= free) and total (= sum of free and inhibitor-bound) RNases. Inhibitor-bound RNase is also referred to as latent RNase. RNase was classified into three types according to pH (acid, neutral, and alkaline RNases) in the pancreatic supernatant fraction. An inhibitor was separated from latent RNase by p-chloromercuribenzoic acid (PCMB), and the latent RNase was changed to an active form. Latent RNase was more active on the alkaline side with a maximum at pH 7.5. Hence, the presence of RNase inhibitor was highly probable in the pancreatic supernatant fraction. RNase inhibitor is most likely a protein, which is bound with both neutral and alkaline RNases. RNase inhibitor may be a cause of nonspecificity and/or low sensitivity of RNase in the serum as a diagnostic marker for pancreatic cancer.
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PMID:Ribonuclease and ribonuclease inhibitor in the human pancreas. 630 4

A method for isolating plasmids from Escherichia coli which requires less than 8 h from cell pellet to purified plasmid essentially free of protein, RNA, and chromosomal DNA is presented. By this procedure, amplified plasmid pBR322 was isolated from E. coli strain RR1. The final product had no detectable protein or RNA, and plasmid comprised approximately 99% of the total DNA. The procedure includes lysozyme treatment in hypertonic solution followed by lysis with a mild detergent in the presence of high salt and an RNase inhibitor--conditions which prevent unfolding of the bacterial nucleoid. After centrifuging out the nucleoid and cell debris, the nucleic acids are selectively precipitated with a neutral solution of sodium trichloroacetate and ethanol. RNA is degraded with RNase and the degradation products and RNase are eliminated through a second trichloroacetate/ethanol precipitation. Finally, the plasmid is resuspended and passed through a nitrocellulose filter to remove aggregates and any residual protein and single-stranded DNA--giving a plasmid preparation suitable for electrophoretic fractionation or cleavage with restriction nucleases.
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PMID:A rapid method for preparation of bacterial plasmids. 635 81

In order to generate the molecular probes needed to investigate the seemingly coordinate expression of carbonic anhydrase (CA I) and beta-globin within erythrocytes during human development, CA I-containing polyribosomes have been isolated from rabbit reticulocytes by reaction with purified antibodies to CA I followed by immunoadsorption of immune complexes with formalin-fixed protein A-bearing bacteria. In the course of such isolation, a series of maneuvers were seen to have a markedly favorable influence on the level of purity attained. These maneuvers include the use of 5 mg/ml of heparin concentrations to attenuate nonspecific binding and entrapment of unwanted polyribosomes, the addition of 200 units/ml of placental ribonuclease inhibitor to augment recovery in reactions which by test already appeared RNase-free, and the preadsorption of polyribosomes with formalin-fixed bacteria prior to immunological reaction so as to remove a subset of polyribosomes seemingly predisposed to nonspecific binding. In the absence of all of the maneuvers, attained purity was no greater than a few per cent. When all were employed, CA I-mRNA derived from immunopurified polyribosomes was recovered with more than 80% purity and 20% yield, as evident from both immunoassays and electrophoresis of its cell-free products.
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PMID:Adjuvants to immunological methods for mRNA purification. Application to the isolation of mRNA for carbonic anhydrase I from rabbit reticulocytes. 640 29

Previous investigations have failed to confirm any specificity of elevated serum ribonuclease (RNase) in the diagnosis of pancreatic cancer. Although RNase had been known to be present in two forms (free and inhibitor-bound) in various rat tissues, little was known about its presence in the human pancreas. This report investigates the presence of RNase inhibitor in the human pancreas through the assay of both active (=free) and total (=sum of free and inhibitor-bound) RNases. Inhibitor-bound RNase was also named as latent RNase. RNase was classified into three types according to pH (acid, neutral, and alkaline RNases) in the pancreatic supernatant fraction. An inhibitor was separated from latent RNase by p-chloromercuribenzoic acid (PCMB), and the latent RNase was changed to an active form. Latent RNase was more active on the alkaline side with a maximum at pH 7.5. Hence, the presence of RNase inhibitor was highly suggested in the pancreatic supernatant fraction. RNase inhibitor is most likely a protein, which binds with both neutral and alkaline RNases. The presence of RNase inhibitor has not yet been demonstrated in the normal human serum.
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PMID:Ribonuclease and ribonuclease inhibitor in the human pancreas. 665 93

Free cytoplasmic mRNPs were isolated from human placenta. An activity of RNase was associated with these particles but was mostly inhibited by a labile protein inhibitor. Both RNase and RNase inhibitor were extractable from mRNPs by 0.5 M KCl. The nature of the association of the RNase-RNase inhibitor complex with mRNPs makes it suitable as a putative system for control of expression and turnover of mRNPs and therefore of protein synthesis.
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PMID:Location of RNase and RNase inhibitor on free cytoplasmic mRNA-protein particles from human placenta. 670 50

Incubation of crude estrogen receptor preparations from mammary tumor cytosol with RNase A increases the sedimentation coefficient of the receptor from 9.7 S to 10.4 S. The effect is not obtained with other low molecular weight basic proteins (lysozyme, cytochrome c, or histone H2B). Nonenzymically active RNase A derivatives such as performic acid oxidized RNase A, fully reductively methylated RNase A, carboxymethyl-His-119-RNase A, and RNase S-protein were ineffective. RNase T1, an acidic endoribonuclease, was also without effect. However, enzymically active RNase S', prepared from a mixture of RNase S-protein and S-peptide, shifted the sedimentation to 10.4 S. The increased sedimentation is not accompanied by a change in the Stokes radius of the receptor (74 A) or buoyant density in metrizamide (1.24 g/ml). The effect of RNase A on the sedimentation of the receptor can be reversed by subsequent incubation with human placental RNase inhibitor or with rabbit anti-RNase A antibodies. Direct interaction was shown by chromatography of the receptor on RNase A Sepharose. Thus, the shift in sedimentation results from binding of RNase A to the receptor and, although this requires that the enzyme active site be available, enzymic activity is not responsible for the effect. The interaction of RNase A with the receptor occurs at low ionic strength; it does not occur at elevated ionic strength or after activation of the receptor by precipitation with ammonium sulfate.
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PMID:Interaction of ribonuclease A with estrogen receptor from rat mammary tumor MTW9. 683 88

Inhibitors of neutral ribonuclease have been purified to homogeneity from beef, pig, sheep, mouse, and rat liver by affinity chromatography on Sepharose-RNase A with overall yields ranging from 60-80%. Each of the purified inhibitors presents a single band by SDS-gel electrophoresis; molecular weight estimates by SDS-gel electrophoresis and by gel filtration are ca. 50 000. Each of the inhibitors forms a complex with beef pancreatic RNase A with a molecular weight of ca. 64 000, suggestive of 1:1 binding on a molar basis. The inhibitors from liver are very similar in properties and amino acid composition to the previously isolated inhibitor from human placenta (Blackburn et al. (1977) J. Biol. Chem. 252, 5904) and beef brain (Burton et al. (1980) Int. J. Peptide Protein Res. 16, 359). Pig liver offers an alternative to human placenta as a source for an RNase inhibitor of this type (yield, ca. 8 mg/kg of tissue). Immunological similarities were examined using antiserum directed against human placental RNase inhibitor. Cross reactivity of the liver RNase inhibitors with the antiserum raised against placental RNase inhibitor ranged from 15% for mouse RNase inhibitor to as low as 2% for pig and sheep RNase inhibitor.
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PMID:Ribonuclease inhibitors from the livers of five mammalian species. 711 7

An endoribonuclease which cleaves only single-stranded RNA has been purified from nucleoli of Ehrlich ascites tumor cells. The molecular weight of the ribonuclease is 50,000 to 52,000 as estimated from sedimentation in glycerol density gradients and by gel filtration on Sephadex G-100. The endoribonuclease requires Mg2+ or Mn2+ (0.2 mM) for optimum activity. Monovalent cations including K+, Na+, and NH+4 are inhibitory. The ribonuclease gave an apparent Km for single-stranded RNA of 30 microM. Using ribohomopolymers, we found that the enzyme could digest single-stranded, poly(C), poly(U), and poly(A) equally well, but would not degrade duplex poly(C) . poly(I) or poly(A) . poly(U). The lack of base specificity was further demonstrated using RNA sequence analysis of partial digest products of yeast 5.8 S RNA. The ribonuclease activity is sensitive to EDTA and N-ethylmaleimide, but is not inhibited by human placental RNase inhibitor. The enzyme makes endonucleolytic cleavages which generate 5'-phosphate-terminated oligonucleotides.
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PMID:Isolation and characterization of a single-stranded specific endoribonuclease from Ehrlich cell nucleoli. 714 16

Protein B23 is an abundant nucleolar protein and putative ribosome assembly factor. The protein was analyzed for ribonuclease activity using RNA-embedded gels and perchloric acid precipitation assays. Three purified bacterially expressed forms of the protein, B23.1, B23.2 and an N-terminal polyhistidine tagged B23.1 as well as the natural protein were found to have ribonuclease activity. However, the specific activity of recombinant B23.1 was approximately 5-fold greater than that of recombinant B23.2. The activity was insensitive to human placental ribonuclease inhibitor, but was inhibited by calf thymus DNA in a dose dependent manner. The enzyme exhibited activity over a broad range of pH with an apparent optimum at pH 7.5. The activity was stimulated by but not dependent on the presence of low concentrations of Ca2+, Mg2+ or NaCl. The Ca2+ effect was saturable and only stimulatory in nature. In contrast, Mg2+ and NaCl exhibited optimal concentrations for stimulation and both inhibited the ribonuclease at concentrations above these optima. These data suggest that protein B23 has intrinsic ribonuclease activity. The location of protein B23 in subcompartments of the nucleolus that contain preribosomal RNA suggests that its ribonuclease activity plays a role in the processing of preribosomal RNA.
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PMID:The ribonuclease activity of nucleolar protein B23. 747 45


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