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)

A CSF Poly(C)-avid ribonuclease (RNase) activity was determined in serum and CSF of 11 controls and 75 neurological patients (34 multiple sclerosis (MS), 18 infectious processes and 23 other neurological diseases (OND]. In controls, the blood-CSF ratio of RNase activity is low. This fact and the absence of correlation between serum and CSF RNase activity (except in OND group), and between CSF albumin and CSF RNase activity in controls and MS patients, suggest an intrathecal origin for the major part of this CSF RNase activity. A formula taking into account any plasmatic enrichment in RNase of the CSF is proposed to evaluate this intrathecal activity. The normal mean value of this intrathecal RNase activity is 27 +/- 3 units/ml (mean +/- SE) in our experimental conditions and using our formula. The highest intrathecal RNase activity is observed in infectious processes and this finding is associated with a significant increase in the local anti-RNA antibody synthesis. An increase in intrathecal RNase activity is rarely found in MS and local anti-RNA synthesis is only observed in one third of MS patients.
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PMID:Intrathecal origin of CSF ribonuclease. Differences between infectious processes of the nervous system and multiple sclerosis. 620 80

Poly(A)-protein particles were prepared from rat liver polyribosomes, washed with 0.5 M KCl or unwashed, after digestion with pancreatic ribonuclease and ribonuclease T1 by two successive rounds of sucrose gradient centrifugation. The particles were sedimented in a range of 5--13 S with a peak at about 9 S. The KCl wash of polysomes had no effect on the sedimentation properties of the particles. The particles isolated in this manner were 99% resistant to further pancreatic ribonuclease treatment and contained about 96% adenylic acid. The length of the poly(A) molecules prepared from the poly(A)-protein particles showed a broad distribution of about 70--290 nucleotides with a peak around 130 nucleotides, as measured by polyacrylamide gel electrophoresis. In CsCl density gradient the poly(A)-protein particles banded in a density range of 1.30--1.42 g/cm3 with a peak at 1.36 g/cm3, which amounts to about 80% of the protein content. Sodium dodecyl sulfate/polyacrylamide and urea/sodium dodecyl sulfate/polyacrylamide gel electrophoresis demonstrated six polypeptides with molecular weights of 50 000, 54 000, 58 000, 63 000, 76 000 and 90 000 in the poly(A)-protein particles, but the main components were dependent on the method. The treatment of polysomes with KCl resulted in a loss of the 90 000-molecular-weight component. Amino acid analysis of the polypeptides bound to poly(A) revealed that they contained a relatively large amount of aspartic plus glutamic acid (21.6%) as well as hydrophobic amino acids (41.4%). Digestion of glutaraldehyde-fixed particles with ribonuclease T2 showed that about 50% of poly(A) was accessible to the enzyme, thus this part of poly(A) was located on the surface of the particles. In the electron micrographs the shadowed poly(A)-protein particles appeared in a globular, somewhat elongated form and were mostly 14-18 nm in diameter. On the basis of the results a model for the 'average' 9-S particles was constructed.
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PMID:Structural characterization of polysomal poly(A)-protein particles in rat liver. 626 Apr 95

An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was isolated from rat liver endoplasmic reticulum. The enzyme yields on gel chromatography four active fractions of different molecular weights (Mr 5.3 X 10(4), 9 X 10(4), 1.55 X 10(5) and Sephacryl S-200 fraction at V0). Each fraction contains polypeptide chains which give a single band on sodium dodecylsulphate electrophoresis (Mr 5.4 X 10(4). This indicates that the enzyme is an oligomeric protein and each of its subunits exhibits the same or very similar molecular weights. Deoxyribonucleoside and ribonucleoside triphosphates can bind to the endoplasmic reticulum nuclease. Binding is enhanced in the presence of divalent cations particularly Mg2+. The enzyme exhibits mainly RNase activity but can also degrade denatured DNA and DNA . RNA hybrids which contain breaks in one of the two strands. Poly(A) and mainly poly(U) are most susceptible to its nucleolytic activity whereas poly(C) is completely resistant.
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PMID:Endoplasmic reticulum nuclease. Purification and specificity. 627 70

Activity of Poly (C) avid ribonuclease was estimated in sera of 129 patients with different malignancies. All patients had histologically verified carcinomas, normal renal function, and no signs of acute catabolic condition. Activity values were compared with those of normal subjects (U-test, Mann and Whitney) separately for each age decade and type of carcinoma. Patients with ovarian and bronchus carcinoma had statistically elevated activity values throughout all age groups. Colon carcinoma patients showed elevated values in most instances. In patients with pancreatic carcinoma a difference could be detected in only one age group (51-60 years of age). No significant elevation of enzyme activity was detected in carcinoma of the stomach and of the prostate. It is concluded that there are carcinomas leading to elevated ribonuclease activity, although the biological basis of this phenomenon is not understood. No special sensitivity nor specificity of ribonuclease elevation could be demonstrated in pancreatic carcinoma patients. Up to now the usefulness of ribonuclease estimation in prospective carcinoma detection remains questionable.
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PMID:Poly (C) avid ribonuclease estimation in patients with solid tumors. A critical evaluation. 670 20

Poly(2-methylthio-7-deazainosinic acid) [poly(ms2c7I)] was enzymatically synthesized by polymerization of 2-methylthio-7-deazainosine 5'-diphosphate with polynucleotide phosphorylase from Micrococcus luteus in high yield. The homopolymer shows much higher thermal stability than its parent polynucleotides poly(7-deazainosinic acid) [poly(c7I)] and poly(I). Its sigmoidal melting curve and pronounced hypochromicity imply a rigid, ordered structure. Poly(ms2c7I), like poly(2-methylthio-inosinic acid) [poly(ms2I)], does not form a complex with poly(C) because of the bulky 2-methylthio substituent. On the other hand, two poly(ms2c7I) strands form very rigid triple strands with poly(A). Different from poly(I) and poly(c7I) the homopolymer poly(ms2c7I) is very stable against cleavage by nuclease S1 and ribonuclease T2 as expected from its rigid secondary structure.
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PMID:Poly(2-methylthio-7-deazainosinic acid)--hydrophobic stabilization of polynucleotide secondary structure by the 2-methylthio group. 688 37

The activity of ribonuclease (E 3.1.4.22) was estimated in sera of 401 normal subjects (normal renal function, no signs of catabolism), age ranging from 16 to 100 years (mean: 50.25 +/- 19.98) with Poly (C) as substrate. Further activity was measured with the substrates Poly (U), Poly (A) and Poly (G) in 10 sera from each age decade between 21-30 years and 81-90 years. Greatest activity was found with Poly (C) as substrate (mean: 15.88 kU/l +/- 9.57). Covariant analysis (age as covariant) revealed no sex-related activity distribution at any age, whereas the age-dependent activity increase was highly significant (p less than 0.001; 11-20 years: 9.48 kU/l +/- 3.07; 81-90 years: 34.72 kU/l +/- 5.88). Activity with the other substrates was very low and constant throughout all ages. It seems to be mandatory to consider the age of the patient when interpreting ribonuclease activity.
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PMID:Evidence of age-dependent activity increase of poly(C)-avid-serum ribonuclease in man. 720 54

Poly(ADP-ribose) synthetic activity in isolated nucleoli from rapidly growing mouse ascites tumor cells and ADP-ribosylation of the nucleolar proteins in vitro were studied. The specific activity of the synthesis in the nucleoli was significantly higher than that in the chromatin. The optimum magnesium and NAD+ concentrations, and the effect of RNase treatment on the reaction in the nucleoli were also distinctly different from those in the chromatin. Hydrolysis of the reaction product of the nucleoli with snake venom phosphodiesterase and with calf thymus poly(ADP-ribose) glycohydrolase yielded 5'-AMP and 2'-(5"-phosphoribosyl))5'-AMP, and ADP-ribose, respectively. The average chain length of the polymer formed in the nucleoli was found to be about 4 as a whole, but the distribution was heterogenous, from 1.2 to over 12. Analysis of ADP-ribosylated proteins in the nucleoli by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that several non-histone proteins with molecular weights of over 100,000 were highly ADP-ribosylated compared with other proteins including histones. This pattern was also different from that of the chromatin. These experimental results demonstrate that the nucleoli are independent from the chromatin as regards poly(ADP-ribose) synthesis in vitro.
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PMID:Poly(ADP-ribose) synthesis in nucleoli and ADP-ribosylation of nucleolar proteins in mouse ascites tumor cells in vitro. 728 63

The distribution of poly(adenylic acid) [poly(A)]-protein complexes in the polysomal and nonpolysomal messenger ribonucleoprotein (mRNP) fractions of Physarum polycephalum was examined in the present study. Poly-(A)-containing components released from the nonpolysomal mRNP by ribonuclease (RNase) digestion were quantitatively adsorbed to nitrocellulose filters at low ionic strength, were highly resistant to micrococcal nuclease under conditions in which free poly(A) was completely degraded, and sedimented as a 10-15S particle which was disrupted by sodium dodecyl sulfate and protease treatment. These are characteristics of the poly(A)-protein complex. In contrast,poly(A)-containing molecules released from the polysomes by RNase were refractive to nitrocellulose, were completely sensitive to micrococcal nuclease, and sedimented at 2-4 S, identical with the sedimentation exhibited by protein-free poly(A). Examination of the poly(A) sequences present in polysomal and nonpolysomal mRNP by polyacylamide gel electrophoresis showed that the former contained only very short sequences, averaging approximately 15 nucleotides, while the latter exhibited only much longer segments, averaging approximately 65 nucleotides. It is concluded that poly(A)-protein complexes are restricted to the nonpolysomal mRNP of Physarum and that the limiting factor in complex formation may be the length of the available poly(A) binding site.
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PMID:The poly(adenylic acid)-protein complex is restricted to the nonpolysomal messenger ribonucleoprotein of Physarum polycephalum. 737 86

A computer model of the complex between G2'p5'G and barnase, the recombinant ribonuclease of Bacillus amyloliquefaciens, was constructed, based on the known structure of the complex RNAase T1.G2'p5'G. This model suggests that the conserved residue Glu-60 plays an important role in the specificity of barnase for guanosine. A barnase mutant was therefore made in which Glu-60 was replaced by Gln. This mutation increases the Km for the dinucleotides GpC and GpA, by a factor of 10, but does not change the kcat. For ApA, the kcat/Km decreases by a similar factor, but the individual parameters could not be determined. The mutation, however, has no influence on the kcat and the Km of barnase action towards RNA and poly(A). This demonstrates that the interactions between the substrate and the residue at position 60 must be different in the case of ApA and poly(A). For RNA, this conclusion is also likely, but not absolutely certain, because barnase/RNA might be a Briggs-Haldane type enzyme/substrate pair. Therefore, if the effect of the mutation were limited to an increase of the dissociation rate constant of the substrate (k-1), this would not be evident in Km or kcat/Km. In view of the clear cut situation with poly(A), the pH profile for and the effect of salt concentration on the kinetic parameters of the mutant barnase were studied for this substrate. The influence of salt on the Km can be interpreted via the linked function concept and shows a cooperative dissociation of 7-10 counterions upon poly(A) binding. The binding of the substrate is strongly reduced at high pH, and the pKa involved decreases strongly at high salt concentrations. Poly(A) and RNA show a pH dependency of their absorbance spectrum, indicating a pH-dependent change of base stacking, which may influence the catalytic parameters.
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PMID:The role of Glu-60 in the specificity of the recombinant ribonuclease from Bacillus amyloliquefaciens (barnase) towards dinucleotides, poly(A) and RNA. 751 56

Poly(A) tail removal is a critical first step in the decay pathway for many yeast and mammalian mRNAs. Poly(A) shortening rates can be regulated by cis-acting sequences within the transcribed portion of mRNA, which in turn control mRNA turnover rates. The AU-rich element (ARE), found in the 3' untranslated regions of many highly labile mammalian mRNAs, is a well-established example of this type of control. It represents the most widespread RNA stability determinant among those characterized in mammalian cells. Here, we report that two structurally different AREs, the c-fos ARE and the granulocyte-macrophage colony-stimulating factor (GM-CSF) ARE, both direct rapid deadenylation as the first step in mRNA degradation, but by different kinetics. For c-fos-ARE-mediated decay, the mRNA population undergoes synchronous poly(A) shortening and is deadenylated at the same rate, implying the action of distributive or nonprocessive ribonucleolytic digestion of poly(A) tails. In contrast, the population of granulocyte-macrophage colony-stimulating factor ARE-containing mRNAs is deadenylated asynchronously, with the formation of fully deadenylated intermediates, consistent with the action of processive ribonucleolytic digestion of poly(A) tails. An important general implication of this finding is that different RNA-destabilizing elements direct deadenylation either by modulating the processivity at which a single RNase functions or by recruiting kinetically distinct RNases. We have also employed targeted inhibition of translation initiation to demonstrate that the RNA-destabilizing function of both AREs can be uncoupled from translation by ribosomes. In addition, a blockade of ongoing transcription has been used to further probe the functional similarities and distinctions of these two AREs. Our data suggest that the two AREs are targets of two distinct mRNA decay pathways. A general model for ARE-mediated mRNA degradation involving a potential role for certain heterogeneous nuclear ribonucleoproteins and ARE-binding proteins is proposed.
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PMID:mRNA decay mediated by two distinct AU-rich elements from c-fos and granulocyte-macrophage colony-stimulating factor transcripts: different deadenylation kinetics and uncoupling from translation. 756 31


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