Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dipolid human fibroblast-rich tissues contain a macromolecule with a molecular weight between 30,000 and 50,000 daltons which will inhibit the proliferation of fibroblasts in the G1 phase of the cell cycle (i.e., inhibit both 3H-thymidine uptake as well as the normal increase in cell number). The inhibitor is destroyed by trypsin but not by ribonuclease or deoxyribonuclease, and it is thermolabile. It has an acid IEP. It is not cytotoxic, and its inhibitory activity appears to be completely reversible. This fibroblast endogenous inhibitor does not interfere with the proliferation of DNA synthesis by human lymphocytes, bronchial carcinoma cells, or HeLa cells. The activity does not appear to be species specific. Therefore, we suggest that it is quite possible that the control of fibroblast proliferation resides in a fibroblast chalone. Diploid human fibroblasts, in contrast to chicken or mouse fibroblasts or heteroploid fibroblasts in general, stringently require serum for their proliferation. All of this mitogenic activity of calf serum can be concentrated in a molecular weight range around 100,000 daltons by ultrafiltration. All of the mitogenic activity within this molecular weight class can be concentrated at a pH of 5.2 via isoelectric focusing, and all of the activity at this isoelectric point can be concentrated in one peak on preparative polyacrylamide gel electrophoresis. This latter material is homogeneous at three different pH's in analytical gel electrophoresis as well as in SDS electrophoresis. This purified serum mitogen for diploid human fibroblasts in vitro also works in vivo and represents as much as 0.5% of calf serum protein, albeit there is much less of this protein in adult cow or horse. It is composed of two equal subunits weighing about 60,000 daltons each and contains about 2 moles of sialic acid, one S-S bond, and 6 moles of hexose per subunit. There is a reciprocal relationship between the biological activity of fibroblast inhibitor and serum mitogen, but there is no apparent direct interaction between these two proteins. Addition of pure serum mitogen to diploid human fibroblasts in vitro results in the release of commensurable chalone activity into the medium and a reciprocal loss of mitogen from the medium. Therefore, we propose that serum contains a single macromolecule which competes with endogenous chalone on the surface of diploid human fibroblasts and that this functions as an anti-chalone for the fibroblast.
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PMID:Circulating factors controlling cell proliferation. 13 64

Several group A coxsackieviruses (A13, 15, 18, and 21), but not polioviruses or group B coxsackieviruses, are rapidly inactivated in low ionic strength solutions at neutral pH. The extent of inactivation is dependent upon temperature and molarity. Virions inactivated in this manner contain a normal complement of infectious RNA which remains in a state resistant to the action of ribonuclease. However, more than 95% of the virus particles are unable to attach to susceptible cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that coxsackievirus A13 virions contain five structural polypeptides (VP1, VP2a, VP2b, VP3, and VP4). Electrophoretic analysis indicates that inactivation of coxsackievirus A13 in low ionic strength solutions is due to the specific loss of the smallest polypeptide VP4 from the virus particle. These results suggest that adsorption of coxsackievirus A13 to receptors on susceptible cells is dependent upon the presence of the capsid protein VP4.
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PMID:Alteration of capsid proteins of coxsackievirus A13 by low ionic concentrations. 16 52

A two-fold increase in polyadenylate [poly(A)] content occurs between fertilization and the two-cell stage in sea urchin zygotes. In this report the role of this cytoplasmic polyadenylation process in the provision of binding sites for poly(A)-associated proteins during early development of Lytechinus pictus is evaluated. Protein-associated poly(A) sequences, from ribonuclease-treated, post-mitochondrial supernatants of various developmental stages, were collected by nitrocellulose filtration and quantified by 3H-poly(U) complex formation. The proportion of protein-associated poly(A) rose from about 27% to about 60% of the total poly(A), on a nucleotide basis, during the period between fertilization and the eight-cell stage. However, the actual increase in number of poly(A) sequences associated with protein was more extensive, about 2.5-fold, since protein-associated poly(A) sequences average about 45 nucleotides longer than free poly(A). The protein-associated poly(A) of eggs and zygotes is found in two types of protease-sensitive complexes which sediment at 8--12 S and 15--20 S. The 8--12 S complex appears to be selectively increased in amount following fertilization. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the poly(A) protein complex fraction indicates the presence of 87,000 and 130,000 molecular weight polypeptides in both eggs and zygotes. It is concluded that quantitative, but not qualitative, alterations in the proportion of protein-associated poly(A) accompanies post-fertilization cytoplasmic polyadenylation in sea urchin zygotes. The attachment of specific proteins to the 3' terminus of maternal RNA's may be involved in their subsequent activities during early embryogenesis.
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PMID:Postfertilization poly(A) . protein complex formation on sea urchin maternal messenger RNA. 75 Feb 68

Purified influenza virus contains ribonuclease activity. The enzyme does not hydrolyze viral RNA but both 28 S and 18 S host cell RNA are degraded forming large (about 16 S) and small (about 5 S) fragments with the release of the acid-soluble material. It has an optimum temperature of 37 degrees C, requires no divalent ions, and is inhibited by 0.1 M EDTA and 1% SDS. Treatment with 4 M urea increases enzymatic activity considerably (42%) but is not a prerequisite for eliciting ribonuclease activity suggesting that the enzyme is probably located near the surface of the virus particle. Results show that the observed enzyme activity is virus-associated as no host cell protein is detectable in the purified virus.
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PMID:Association of a ribonuclease with the purified influenza virus. 81 84

A highly purified membrane preparation derived from the microsomal fraction of rat hepatocytes has been chemically characterized and fractionated by means of gel filtration. The preparation has been freed of ribosomes and intravesicular protein and has a composition on a w/w basis of 52.1% protein, 45.0% phospholipid, 2.9% carbohydrate and no RNA. 97 +/- 2% of the total membrane phosphorus is accounted for as phospholipid phosphorus. Determination of the molecular weight distribution of the constituent polypeptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave values ranging from 171 000 to 16 000 for the major classes of proteins. Although several membrane glycoproteins have been indentified, the most prominent species has an apparent molecular weight of 171 000, 40% of the total microsomal protein is present in the 49 000-60 000 molecular weight region. Examination of the intrinsic polypeptide composition of membranes obtained from smooth and degranulated rough endoplasmic reticulum revealed no detectable qualitative differences. Sodium dodecyl sulfate-solubilized microsomal membrane proteins were separated by gel filtration into much simplified molecular weight classes, some of which showed predominantly a single electrophoretic component. Amino acid analysis of individual fractions showed a noticeable trend toward a decreasing ratio of acidic to basic residues with decreasing molecular weight. Membrane phosphorus was distributed between two chromatographic fractions: one containing membrane phospholipid (97% of the total) as well as essentially all the cholesterol, the other, at the inclusion volume of the gel filtration system, containing small molecular weight species (3% of the total phosphorus). The absence of a ribonuclease-resistant RNA component eluting near the void volume clearly distinguishes the microsomal membrane from the nuclear envelope.
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PMID:Characterization of the membrane matrix derived from the microsomal fraction of rat hepatocytes. 127 22

A process for conformational modification of protein, which we have previously reported, was investigated as a means of generating fluorohydrolase activity in bovine ribonuclease (RNase). The resulting modified RNase had catalytic activity that depended upon the chosen modifier. Bovine pancreatic ribonuclease, modified by addition of hexamethylphosphoramide (HMPA) at pH 3, was derivatized with diimidates of chain lengths from C1 to C8. The derivative with the highest activity was obtained when RNase was crosslinked with dimethyl pimelimidate (C5). This derivative, which was active over a pH range of 6.5 to 8.0 with an optimum pH of 7.4, hydrolyzed phenylmethylsulfonylfluoride (PMSF) and the potent acetylcholinesterase inhibitor, diisopropyl phosphorofluoridate (DFP). The mean fluorohydrolase activity for four preparations using dimethyl pimelimidate was 0.8 +/- 0.2 U mg-1. Gel filtration on G-75 Sephadex and SDS-polyacrylamide gel electrophoresis showed components having a molecular weight of 13,000 and 27,000, with activity restricted to the 27,000 molecular weight fraction. After gel filtration, the specific activity was 9.1 +/- 2.4 U mg-1, resulting in a molecular activity of 125 min-1. The mechanism of this unique transformation of RNase into a fluorohydrolase is not known, nor has the location of the active site been determined.
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PMID:Semisynthetic fluorohydrolases prepared by chemical modification of ribonuclease. 136 89

A pyrimidine-guanine sequence-specific ribonuclease (RC-RNase) was purified from Rana catesbeiana (bullfrog) oocytes by sequential phosphocellulose, Sephadex G75, heparin Sepharose CL 6B and CM-Sepharose CL 6B column chromatography. The purified enzyme with molecular weight of 13,000 daltons gave a single band on SDS-polyacrylamide gel. One CNBr-cleaved fragment has a sequence of NVLSTTRFQLNT/TRTSITPR, which is identical to residues 59-79 of a sialic acid binding lectin from R. catesbeiana eggs, and is 71% homologous to residues 60-80 of an RNase from R. catesbeaina liver. The RC-RNase preferentially cleaved RNA at pyrimidine residues with a 3' flanking guanine under various conditions. The sequence specificity of RC-RNase was further confirmed with dinucleotide as substrates, which were analyzed by thin layer chromatography after enzyme digestion. The values of kcat/km for pCpG, pUpG and pUpU were 2.66 x 10(7) M-1s-1, 2.50 x 10(7) M-1s-1 and 2.44 x 10(6) M-1s-1 respectively, however, those for other phosphorylated dinucleotides were less than 2% of pCpG and pUpG. As compared to single strand RNA, double strand RNA was relatively resistant to RC-RNase. Besides poly (A) and poly (G), most of synthetic homo- and heteropolynucleotides were also susceptible to RC-RNase. The RC-RNase was stable in the acidic (pH 2) and alkaline (pH 12) condition, but could be inactivated by heating to 80 degrees C for 15 min. No divalent cation was required for its activity. Furthermore, the enzyme activity could be enhanced by 2 M urea, and inhibited to 50% by 0.12 M NaCl or 0.02% SDS.
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PMID:A pyrimidine-guanine sequence-specific ribonuclease from Rana catesbeiana (bullfrog) oocytes. 137 37

1. In a previous report we described three isozymes of intracellular ribonuclease in Dictyostelium discoideum, which were found in vegetative cells. Here we report that the molecular weights of the three isozymes from vegetative cells. 2. They are 14.3 kDa, 60 kDa and 80 kDa, as determined by activity-staining of gels after SDS-PAGE. 3. For renaturation of ribonucleolytic activity from D. discoideum cells after SDS-PAGE, fibrinogen-containing gels were used and gels were washed in aqueous isopropanol to remove detergent. Results of studies by this method suggest that each of these isozymes is composed of only a single polypeptide. 4. The effect of the buffer system on this technique is discussed.
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PMID:Determination of the molecular weights of ribonuclease isozymes in a cell-free crude extract of Dictyostelium discoideum, by activity-staining of gels after SDS-PAGE. 137 16

An extracellular nuclease gene of Bacillus subtilis was cloned in the same organism by detecting the amplified enzyme activity, which was secreted from the transformant cells on an RNA-containing agar medium. An open reading frame encoding 289 amino acids was identified within the cloned fragment. The transcriptional initiation site was determined by nuclease S1 mapping and the promoter region showed similarity to the conserved recognition sequences for the E sigma A and/or E sigma E RNA polymerases. The production of the nuclease by the B. subtilis transformants greatly depends on the liquid medium used. SDS/PAGE analysis of the purified enzyme showed two adjoining bands of molecular mass about 32 kDa, and the NH2-terminal amino acid sequence analysis suggested that the NH2-terminal portion of the nuclease was subjected to a limited proteolysis after or during secretion. The nuclease was uniquely characterized as a Mg(2+)-activated ribonuclease which hydrolyzes RNA apparently nonspecifically into oligonucleotides with 5'-terminal phosphate. The deduced amino acid sequence of this enzyme shows no obvious similarity with other nuclease sequences.
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PMID:Gene cloning and characterization of a novel extracellular ribonuclease of Bacillus subtilis. 139 90

The pyrE gene, encoding the pyrimidine biosynthetic enzyme orotate phosphoribosyltransferase, is the promoter distal gene of the dicistronic orfE-pyrE operon. The promoter proximal orfE gene, whose transcription and translation is important for regulation of the pyrE attenuator, encodes a 238-amino acid residue protein which was recently identified as the phosphorolytic ribonuclease, RNase PH, that removes nucleotides from the 3' ends of tRNA precursors. In this paper we report the construction of a plasmid, which overexpresses the orfE and pyrE gene products substantially, as well as the purification of the OrfE protein by ammonium sulfate precipitation and chromatography on phosphocellulose. The highly purified protein catalyzes the phosphorolytic cleavage of poly(A) at a rate of 1.6 mumol/min/mg and the formation of CDP from tRNA-CCA-Cn and orthophosphate at a rate equal to 0.14 mumol/min/mg, as characteristic for RNase PH. OrfE/RNase PH contains helix-turn-helix motifs resembling those in DNA-binding proteins, and it binds nonspecifically to DNA. On SDS gels, OrfE/RNase PH migrates as two distinct protein bands. This heterogeneity might be caused by post-translational modification other than proteolysis, or may be an electrophoretic artifact. The native protein is composed of two or more subunits.
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PMID:Overexpression and rapid purification of the orfE/rph gene product, RNase PH of Escherichia coli. 151 52


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