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)

The binding of taurodeoxycholate to pancreatic lipase and a few other proteins has been studied with equilibrium dialysis and in gel filtration experiments. A three compartment dialysis cell has been used; with this cell, complete equilibration is not necessary for calculation of the binding even at bile salt concentrations above the critical micellar concentration. The results indicate that taurodeoxycholate does not bind to lipase below the critical micellar concentration, that the binding starts in the critical micellar concentration range of the bile salt and reaches around 12 mol taurodeoxycholate per mol of lipase at taurodeoxycholate concentrations well above the critical micellar concentration. Previous results indicating a binding of maximally 1-2 mol taurodeoxycholate/mol lipase were too low, depending on the experimental conditions in which complete equilibration was not obtained. The binding isotherm for taurodeoxycholate to lipase is similar to that for co-lipase; colipase and lipase in mixture bind as much taurodeoxycholate as the sum for the single proteins. Taurodeoxycholate binds to ribonuclease and chymotrypsinogen to a similar extent as to lipase.
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PMID:On the binding of bile salt to pancreatic lipase. 100 92

Until now it has not been possible to obtain nuclear bodies from Escherichia coli after treatment with rifampicin. It was generally assumed that the cross-connections between the DNA double strands which are sensitive towards ribonuclease are destroyed under the influence of inhibitors of RNA synthesis like rifampicin. In this paper a new lysis procedure is described for preparing nuclear bodies from E. coli. These particles differ in some respects, especially in salt sensitivity from those prepared by earlier methods. Using the new lysis method it is also possible to obtain folded chromosomes from cells after treatment with rifampicin. These nuclear bodies can be destroyed by ribonuclease. Therefore, it has to be postulated that a fraction of RNA being sufficient to hold the chromosome in the folded shape is not susceptible to the action of rifampicin.
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PMID:A mild method for the isolation of folded chromosomes from Escherichia coli. 110 41

Preparative agarose gel electrophoresis under denaturing conditions has been successfully employed to purify large quantities of ovalbumin mRNA from hen oviducts. The mRNA thus prepared is physically homogeneous based on its migration as a single component on electrophoresis in both analytical acid-urea agarose gels and formamide-containing, neutral polyacrylaminde gels; it also sediments as a single peak in sucrose gradients containing 70% formamide. The mRNA is chemically free of ribosomal RNA contamination since its oligonucleotide fingerprint map after complete T1 ribonuclease digestion contains no detectable specific large oligonucleotide markers of ribosomal RNAs. It is also not contaminated by other biologically active messenger RNAs because, when it is added to the cell-free wheat germ translation system, the only protein product synthesized is ovalbumin as analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and specific immunoprecipitation. Ovalbumin mRNA has a nucleotide composition of 32.3% A, 21.0% G, 25.7% U, and 20.7% C [(A+U)/(G+C) equal 1.41]. The mRNA contains a heterogeneous poly(A) tract ranging from 20 to 140 residues with a number average chain length of 62 adenylate residues. The molecular weight of the sodium salt of the purified mRNA is approximately 650,000 +/- 63,000, corresponding to a chain length of 1890 +/- 180 nucleotides, as determined by electron microscopy under completely denaturing conditions. This value is in close agreement with the values obtained from: (a) sucrose gradient centrifugation in the presence of 70% formamide; (b) evaluation of poly(A) content in the mRNA and the number average chain length of its poly(A) tract; and (c) sedimentation velocity studies in the presence of 3% formaldehyde. When 125I-labeled ovalbumin mRNA is allowed to hybridize with a large excess of chick DNA, the observed kinetics of hybridization reveal no appreciable reaction between the mRNA and the repeated sequences of the chick DNA, although the mRNA appears to be approximately 600 nucleotides longer than necessary to code for ovalbumin. It thus appears that the entire ovalbumin mRNA is primarily transcribed from a unique sequence in the chick genome.
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PMID:Physical and chemical characterization of purified ovalbumin messenger RNA. 115 96

Over half of the chloroplast ribosomes isolated from growing cultures of Chlamydomonas reinhardtii are bound to chloroplast thylakoid membranes if completion of nascent polypeptide chains is prevented by chloramphenicol. The free chloroplast ribosomes are recovered in homogenate supernatants, and presumably originate from the chloroplast stroma. Only about 10% of these free chloroplast ribosomes are polyribosomes, even under conditions when 70% of free cytoplasm ribosomes are recovered as polyribosomes. The nonionic detergent Nonidet P-40 liberates atypical polyribosomes (Type I), from membranes, which require both ribonuclease and proteases for complete conversion to monomeric ribosomes. Thus Type I particles are held together by mRNA but are also held together by peptide bonds. These Type I polyribosomes probably are not bound to intact membrane, but might be bound to some protein-containing sub-membrane particle. The Type I polyribosomes are dissociated to ribosomal subunits by puromycin and high salt, and contained 0.2 to 1 nascent chain per ribosome. If membranes are treated with Nonidet and proteases at the same time, polyribosomes which are digested to monomeric ribosomes by ribonuclease alone (Type II) are obtained. Type II polyribosomes are smaller than Type I, and probably represent the true size distribution of polyribosomes on the membranes. At least 50% of the membrane-bound ribosomes are polyribosomes, since that much membrane bound chloroplast RNA is recovered as Type I or Type II polyribosomes.
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PMID:Free and membrane-bound chloroplast polyribosomes Chlamydomonas reinhardtii. 116 19

Mild ribonuclease treatment of the membrane fraction of P3K cells released three types of membrane-bound ribosomal particles: (a) all the newly made native 40S subunits detected after 2 h of [3H]uridine pulse. Since after a 3-min pulse with [35S]methionine these membrane native subunits appear to contain at least sevenfold more Met-tRNA per particle than the free native subunits, they may all be initiation complexes with mRNA molecules which have just become associated with the membranes; (b) about 50% of the ribosomes present in polyribosomes. Evidence is presented that the released ribosomes carry nascent chains about two and a half to three times shorter than those present on the ribosomes remaining bound to the membranes. It is proposed that in the membrane-bound polyribosomes of P3K cells, only the ribosomes closer to the 3' end of the mRNA molecules are directly bound, while the latest ribosomes to enter the polyribosomal structures are indirectly bound through the mRNA molecules; (c) a small number of 40S subunits of polyribosomal origin, presumably initiation complexes attached at the 5' end of mRNA molecules of polyribosomes. When the P3K cells were incubated with inhibitors acting at different steps of protein synthesis, it was found that puromycin and pactamycin decreased by about 40% the proportion of ribosomes in the membrane fraction, while cycloheximide and anisomycin had no such effect. The ribosomes remaining on the membrane fraction of puromycin-treated cells consisted of a few polyribosomes, and of an accumulation of 80S and 60S particles, which were almost entirely released by high salt treatment of the membranes. The membrane-bound ribosomes found after pactamycin treatment consisted of a few polyribosomes, with a striking accumulation of native 60S subunits and an increased number of native 40S subunits. On the basis of the observations made in this and the preceding papers, a model for the binding of ribosomes to membranes and for the ribosomal cycle on the membranes is proposed. It is suggested that ribosomal subunits exchange between free and membrane-bound polyribosomes through the cytoplasmic pool of free native subunits, and that their entry into membrane-bound ribosomes is mediated by mRNA molecules associated with membranes.
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PMID:Membrane-bound ribosomes of myeloma cells. III. The role of the messenger RNA and the nascent polypeptide chain in the binding of ribosomes to membranes. 117 34

We identified conditions for heating and quick cooling viroid RNAs in the presence of salt which lead to the production of conformational isomers stable to incubation for at least 45 minutes at 30 degrees in the presence of magnesium ions. Elution in 0.3 M NaCl allowed the purification of an electrophoretically slow form of an in vitro transcript carrying a complete copy of the potato spindle tuber viroid RNA sequence. Slow forms of this transcript and of kinase-labeled linear viroid RNA persisted for longer than 20 minutes when incubated with a protein-rich extract prepared from the nuclei of uninfected tomato plants, although both were slowly cleaved by a nuclease present in this extract. The fast form of the transcript was highly resistant to this tomato ribonuclease. The slow form of the transcript was much more susceptible to cleavage by RNase T1 than the fast form of this RNA, suggesting that the reduced gel mobility of the slow forms results from their relatively open structure. The ability to purify viroid conformational isomers from polyacrylamide gels will facilitate biochemical studies aimed at identifying host components interacting with RNAs of the viroid replication complex, which may not all be present in the most thermodynamically favored rodlike structure of mature viroids.
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PMID:Generation of viroid conformational isomers that are stable to incubation with magnesium ions and in a nuclear extract from tomato plants. 128 3

We have investigated the ability of dehydroepiandrosterone (DHEA) to alter the production of interleukin-2 (IL-2) and to bind to a specific binding complex in antiCD3 epsilon activated T cells. Binding activity correlated with the presence of a specific DHEA binding complex in the cytosol and nuclei of DHEA-responsive T-cell hybridomas, as well as in CD4+ and CD8+ cells isolated from peripheral lymph nodes of normal mice. Scatchard analysis determined that intact lymphocytes and cytosolic fractions contained high affinity binding for [3H]DHEA (approx. 2.6 nM) with 1000-7000 binding sites existing per cell. Five of the T-cell hybridomas tested both responded to DHEA treatment with increased production of IL-2 and also contained specific high affinity [3H]DHEA binding. Four additional T-cell hybridomas were found to contain no specific [3H]DHEA binding and were also unresponsive to DHEA influences on IL-2 production. Sucrose density gradients demonstrated a 3-4s [3H]DHEA binding complex in high salt and a 7-8s binding complex in low salt. Specific binding was inhibited by preincubation of the cytosol fractions with either trypsin or chymotrypsin, or by heating to 60 degrees C for 1 h (less than 15% of control). [3H]DHEA binding was unaffected by preincubation of the cytosol fractions with ribonuclease, deoxyribonuclease, or phospholipase A. The DHEA-protein complexes bound to DNA-cellulose with the amount of binding being slightly increased by preincubation at 25 degrees C as compared to 4 degrees C. As expected, [3H]DHEA binding was inhibited by the addition of unlabeled DHEA, but was also modestly inhibited by dihydrotestosterone and cortisol. Binding of DHEA was unaffected by progesterone, dexamethasone, estradiol, androsterone, DHEAS, and beta-etiocholanolone at all concentrations tested. DHEA was incapable of inhibiting the binding of [3H]DHT to the androgen receptor or [3H]dexamethasone to the glucocorticoid receptor. Collectively, these findings suggest that murine T cells contain a specific DHEA receptor. We believe that DHEA is a steroid hormone that is directly involved in the regulation of IL-2 production by both normal and some T-cell hybridomas.
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PMID:The presence of a dehydroepiandrosterone-specific receptor binding complex in murine T cells. 135 1

Rat pancreatic secretory proteins were separated by an automated liquid chromatography system utilizing a Mono S cation-exchange column. Optimal resolution was obtained with a multistep salt and pH gradient (0.01-2 M LiCl, pH 5.3-63). A total of fourteen well-separated peaks, as well as several minor peaks, were detected by UV absorption. The main pancreatic enzymes were resolved (two amylases, two chymotrypsinogens, two trypsinogens, proelastase, lipase, prophospholipase A2, procarboxypeptidase A, procarboxypeptidase B, and ribonuclease). In addition, proteins without enzymic activity, such as lithostathine and pancreatitis-associated protein, were identified. Activation of proenzymes did not occur during the separation. At a flow-rate of 0.5 ml/min, ca. 250 micrograms to 5 mg of protein could be applied with equal resolution. The reproducibility of retention volumes and peak areas was high (less than 1% or 5% variation, respectively). When radiolabeled proteins were separated, a comparable pattern of peaks was obtained. The technique described is, therefore, not only useful for analytical and preparative separation of pancreatic proteins but can additionally serve for quantitative determination of the pancreatic isoenzyme pattern.
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PMID:Separation of rat pancreatic secretory proteins by cation-exchange fast protein liquid chromatography. 140 Jul 16

Fibronectin expression was shown recently to increase in the rat aorta in response to experimental hypertension. Fibronectin is known to alter the phenotype of vascular smooth muscle and endothelial cells, and relative changes in the expression of different isoforms of fibronectin, generated by alternative splicing and distinguished by the absence or presence of inserts designated as EIIIA, EIIIB, and V, may reflect a change in cell phenotype. In the present study we examined the expression of alternatively spliced forms of aortic fibronectin during deoxycorticosterone-salt hypertension. Aortic RNA was analyzed quantitatively using Northern blot analysis and ribonuclease protection assays. Using Northern blot analysis, deoxycorticosterone-salt treatment for 21 days led to a 4.9-fold increase in EIIIA fibronectin messenger RNA, while EIIIB and V forms increased by 2.6- and 2.5-fold, respectively. As determined by ribonuclease protection assays, the percentage of fibronectin transcripts containing either EIIIA, EIIIB, or V in control aorta was 7.3%, 19%, and 40%, respectively. The percentage of EIIIA transcripts increased 42% over control levels after 21 days of deoxycorticosterone-salt treatment, whereas no proportionate change in the other alternatively spliced forms was found. Thus, all forms increased, but a selective increase in the EIIIA form was induced. Analogous increases in each of the fibronectin isoforms were found in the spontaneously hypertensive rats when compared with age-matched Wistar-Kyoto or Wistar rats, and 40-week-old animals showed increases over 10-week-old animals in all strains, consistent with an age-dependent increase in aortic fibronectin expression.
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PMID:Hypertension induces alternatively spliced forms of fibronectin in rat aorta. 161 48

Affinity-purified human placental ribonuclease inhibitor (PRI) was digested by trypsin. Subsequent fractionation of the hydrolysate by HPLC yielded 44 fractions, 3 of which retained the ability to inhibit ribonuclease. One of these, the most active, was a 15 amino acid peptide which had an amino acid composition corresponding to a tryptic fragment of PRI. This peptide was synthesised, and preliminary experiments were carried out on its interactions with ribonuclease. These experiments suggested that the behaviour of the peptide in terms of effect of pH, and effect of salt concentration were similar to the protein from which it was derived. These studies together with the strategic positioning of the peptide in the sequence of the ribonuclease inhibitor, suggest that this segment of PRI has an important role in the inhibitory activity of the intact protein.
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PMID:Characterisation of a tryptic peptide from human placental ribonuclease inhibitor which inhibits ribonuclease activity. 163 92


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