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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly-[C]-specific ribonuclease (RNase) is released in large amounts from rat pancreas incubated at 37 degrees C in isotonic saline solution. Pancreatic cell disruption by homogenization releases only 10% of that RNase. The remainder, perhaps membrane-bound, is freed only after further membrane deterioration during anoxic incubation. Other tissues (small intestine, stomach, colon, liver, spleen, kidney, muscle, and skin) do not appear to contain much of this RNase or to release it during anoxic incubation. Relatively little amylase is released from the pancreas under the conditions that release RNase. The findings provide a rational basis for monitoring serum RNase levels in patients with acute pancreatitis for early detection and treatment of pancreatic necrosis in man.
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PMID:Release of ribonuclease from anoxic pancreas. 620 Sep 44

Preparations of isolated brush border plasma membrane of Hymenolepis diminuta and H. microstoma possess the following enzymatic activities: alkaline phosphohydrolase (E.C. 3.1.3.1); Type I phosphodiesterase (E.E. 3.1.4.1); ribonuclease (E.C. 3.1.4.22); adenosine triphosphatase (E.C. 3.6.1.3); and 5'-nucleotidase (E.C. 3.1.3.5). The following enzymatic activities could not be demonstrated in either membrane preparation: Type II phosphodiesterase (E.C. 3.1.4.18); cyclic adenosine-3', 5'-monophosphate phosphodiesterase (E.C. 3.1.4.17); leucine aminopeptidase (E.C. 3.4.11.1); maltase (alpha-glucosidase; E.C. 3.2.1.20); and lactase (beta-galactosidase; E.C. 3.2.1.23). These data generally agree with those of previous studies in which similar membrane-bound enzymes were demonstrated in intact (living) worms.
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PMID:A comparison of membrane-bound enzymes of the isolated brush border plasma membranes of the cestodes of Hymenolepis diminuta and H. microstoma. 628 Jan 22

The ability of nonionic detergents to solubilize the membrane-bound enzymes of the brush-border plasma membrane of Hymenolepis diminuta was investigated. Of the detergents tested (Triton X-100, Tween 80, Brij 35, Lubrol PX and WX, W-1, and beta-octyl-D-glucoside), only Triton was an effective solubilizing agent. Optimal solubilization was achieved by incubating an isolated fraction of the brush-border membrane in the presence of 1% Triton X-100 for 60 min at 37 C, followed by centrifugation at 100,000 g for 60 min at 25 C. This treatment resulted in solubilization of 94% of the alkaline phosphohydrolase, 91% of the phosphodiesterase and ribonuclease, and 88% of the 5'-nucleotidase activities. The pH optima for enzymes solubilized in nonionic and ionic detergents (Triton and sodium dodecyl sulfate, respectively) did not differ. Isoelectric focusing of the Triton-solubilized material demonstrated the presence of at least 14 polypeptides, a majority of which had isoelectric points below pH 7.
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PMID:Solubilization of the membrane-bound enzymes of the brush-border plasma membrane of Hymenolepis diminuta (Cestoda) using nonionic detergents. 628 6

Mammary gland polysomes are difficult to isolate from the lactating rat using methods developed for other species and tissues, most likely due to high calcium-stimulated ribonuclease activity in that tissue. A new method, utilizing ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) to bind calcium, yields highly aggregated polysomes from lactating rat mammary gland. Fresh mammary tissue is pulverized under liquid nitrogen. Free and membrane-bound polysomes are isolated by differential centrifugation in solutions containing 100 mM KCl, 100 mM MgCl2, 75 mM EGTA, 500 micrograms/ml heparin and 50 mM Tris buffer, pH 8.2 at 5 degrees C. Bound polysomes are released from the endoplasmic reticulum using Triton X-100 and deoxycholate. Polysome profiles are obtained on linear sucrose gradients and scanned at 254 nm. The method gives quantitative recovery of homogenate total RNA. To demonstrate that the method can be used to study nutritional effects on mammary gland polysome aggregation, lactating rats were fasted 22-66 h and then refed a stock diet for 71-95 h. Refeeding increased the percentage of polysomes (trimers or larger) in the bound fraction from 84 +/- 1 to 93 +/- 1% (P less than 0.001) and in the free fraction from 42 +/- 2 to 55 +/- 3% (P less than 0.001).
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PMID:A method for isolation of undegraded free and membrane-bound ribosomes from rat lactating mammary gland. 642 19

The method of Ramsey and Steele [Anal. Biochem., 92 (1979) 305--313] was used to examine the size distribution of membrane-bound and free polyribosomes from the liver of male C57 BL/6 mice over the life span. Optimization of the concentration of Mg2+ and liver cell sap suppressed breakdown by ribonuclease and presumably gave preparations that approximate the integrity of native polyribosome populations. The content of polysomes per unit liver tissue from 7 groups of fed mice aged 10--35 months showed an age-related increase of subunits and monomers (+54%) and dimers-to-pentamers (+76%) in membrane-bound polyribosomes. The dimer-to-pentamer class of free polyribosomes also increased (+52%). Polysomes larger than nonamers showed 13% and 21% decreases that were not statistically significant. Total tissue ribosomes increased 15%, while the membrane-bound/free polyribosome ratio remained nearly constant at about 1.15. In a subsequent study, both 6 h-fasted and fed mice showed decreases (-20% to -33%) in membrane-bound and free polyribosomes larger than nonamers during aging from 15 to 35 months. The dimer-to-pentamer class of free polyribosomes in fed mice increased (+26%), while this class in the other groups underwent increases (+26 to +39%) that were not statistically significant. We conclude that the liver in old mice is not obviously deficient in either quantity or general quality of ribosomes. Old animals do tend to show an increase in small polysomes and a decrease in large polysomes, which is consistent with a reduction in the rate of translation.
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PMID:The content and size distribution of membrane-bound and free polyribosomes in mouse liver during aging. 649 84

During growth and maturation of the tapeworm, Hymenolepis diminuta, significant decreases occur in the brush border membrane-bound alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities. These decreases are accompanied by qualitative and quantitative changes in the polypeptide profiles of the brush border membrane fraction. Gradients of enzymatic activities and polypeptide profiles are also demonstrable when mature tapeworms are cut into pieces and the brush border membrane of each piece analyzed individually. In fully developed tapeworms the enzymatic activities and polypeptide profiles of membrane preparations reflect mainly the contributions of the more mature proglottids; these proglottids constitute most of the tapeworm biomass. The most anterior sections of these fully developed worms are biochemically similar to young, developing worms.
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PMID:Alterations in brush border membrane proteins and membrane-bound enzymes of the tapeworm, Hymenolepis diminuta, during development in the definitive host. 663 65

Previously we reported that chronic renal failure in rats leads to preferential disaggregation of liver membrane-bound polysomes associated with a decrease in albumin synthesis. To determine whether reduced albumin synthesis results from reduced cellular levels of albumin messenger RNA (mRNA) or some other molecular mechanism, we have employed mRNA-DNA hybridization in conjunction with cell-free protein synthesis to determine albumin mRNA sequence content and biological activity in subcellular fractions from control and uremic rat liver. Using high specific activity albumin [3H]-complementary DNA prepared from purified-albumin mRNA, we found that total liver polysomes and albumin mRNA sequence content are increased in uremic animals. The extra polysomes are located within the membrane-bound subcellular fraction. These polysomes, however, have reduced ability to synthesize albumin in the cell-free system, and mRNA isolated from membrane-bound polysomes of uremic liver showed reduced albumin synthesis. Evaluation of albumin mRNA size by hybridization analysis revealed a reduced content of intact albumin mRNA molecules per microgram of RNA in the liver of uremic animals. This was associated with increased ribonuclease activity in uremic cytosol. The diminished albumin synthesis by membrane-bound polysomes of uremic rat liver can, therefore, be explained by enhanced degradation of albumin mRNA.
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PMID:Effects of chronic renal failure on protein synthesis and albumin messenger ribonucleic acid in rat liver. 670 9

Acholeplasma laidlawii A has been grown in media containing synthetic, long chain C20- and C23-fatty acids possessing a diacetylene group in their acyl chains. Growth on the C23 diacetylenic acid was poor but was good on the C20 acid. Biosynthetic incorporation of the fatty acids occurs; as much as 90% of the membrane lipid fatty acyl chains consisting of the C20-diacetylenic fatty acid, the remainder being shorter chain, saturated fatty acids. The thermal phase transition of this biomembrane has been studied and a differential scanning calorimetry heating curve shows the presence of an endotherm corresponding to a membrane lipid phase transition occurring at about 26 degrees C. The lipid class composition of membranes containing the C20-diacetylene lipids was examined and found to be similar to membranes from cells grown on oleic acid-containing medium. (The ratio of monoglucosyl- to diglucosyldiacylglycerols was the same but the ratio of glycolipid to phosphatidylglycerol was higher in the cells grown with diacetylene fatty acids). Upon irradiation with ultraviolet light the cells and isolated biomembranes become coloured, either red or yellow depending upon their thermal history. The colour change indicates that extensive cross-linking of the lipids of the biomembranes of A. laidlawii has occurred and that a conjugated polymeric structure has been formed. Analysis of the extracted lipids from the biomembranes by GLC indicates that extensive cross-linking of the lipid chains within the biomembrane of a natural cell system has been achieved. The monoglucosyldiacylglycerols cross-link more readily that do the phosphatidylglycerol lipids. The effect of such lipid cross-linking or polymerisation on the activity at 35 degrees C of an intrinsic membrane-bound enzyme, NADH oxidase, and ribonuclease, an extrinsic membrane-bound enzyme, was studied. The NADH oxidase activity decreased rapidly upon cross-linking of the lipid environment whereas ribonuclease activity was unaffected. The potential for future studies of polymerised model and natural biomembranes is discussed.
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PMID:The biosynthetic incorporation of diacetylenic fatty acids into the biomembranes of Acholeplasma laidlawii A cells and polymerisation of the biomembranes by irradiation with ultraviolet light. 683 76

The structure of the free zoospores of Neocallimastix frontalis has been examined by electron microscopy of thin-sectioned and negatively stained preparations. There are up to 15 flagella arranged in two rows. The free end of each flagellum is narrow and its tip does not contain microtubules. The flagella and the cell body are coated with distinct surface layers composed of regular arrays of particles and fibrils, respectively. The cell body contains a variety of inclusions. Near to the flagellar pole there are numerous membrane-bound electron-dense globules about 0.2 to 0.7 mum in diameter, between which are microtubules, particles and small vesicles. In the region of the centrally placed nucleus are arrays of helices of ribosome-like particles. These particles also occur in the form of globular aggregates, each partially enclosed within a membrane. The remainder of the cytoplasm is filled with material resembling glycogen. The zoospores stain positively for glycogen and contain ribonuclease-sensitive particulate material which is stained by toluidine blue. Scanning electron microscopy shows that the zoospores attach to the substrate by the flagellar pole.
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PMID:Ultrastructural studies of the free zoospore of the rumen phycomycete Neocallimastix frontalis. 719 79

Plasma membrane from the brush border isolated from the tegument of Hymenolepis diminuta contains membrane-bound ribonuclease (RNase) and alkaline phosphatase activities. RNase (yeast RNA substrate), alkaline phosphatase (p-nitrophenyl phosphate substrate), and additional membrane proteins were solubilized by sonication or treatment with the detergents dodecyl trimethylammonium bromide, beta-octyl-D-glucopyranoside, sodium dodecyl sulfate (SDS), or ZwittergentTM 3-12 (N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate). At optimal conditions, greater than 90% of both enzymes and total protein were solubilized by the latter two detergents, whereas beta-octyl-D-glucopyranoside, dodecyl trimethylammonium bromide, and sonication were only partially effective. Nonionic detergents did not solubilize the membrane effectively.
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PMID:Solubilization of membrane-bound ribonuclease (RNAse) and alkaline phosphatase from the isolated brush border of Hymenolepis diminuta (Cestoda). 739 87


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