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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)

Sodium acetate and sulphuric acid extracts of human epidermis can each be separated by chromatographic techniques into three or more fractions with ribonuclease activity. Eight of these fractions were compared with respect to molecular weight, pH activity profile, polyribonucleotide hydrolysis, and activity in the presence of low levels of spermidine. Sodium acetate and sulphuric acid extracts were also prepared from callus and from psoriatic lesions and compared with extracts from normal epidermis for their response to exogenous spermidine. All eight human epidermal ribonuclease fractions studied had an apparent molecular weight of 15,000 daltons. Seven of the ribonuclease fractions were optimally active at alkaline pHs (pH 7.3-7.6 in sodium phosphate and pH 8.I in Tris-HCl) while the eighth ribonuclease was most active at pH 5.6 in a citrate-phosphate buffer. All enzymes hydrolyzed polycytidylic acid and five also hydrolyzed polyuridylic acid. None hydrolyzed polyadenylic acid. Seven of the eight ribonucleases studied exhibited greater activity in the presence of added spermidine. The extracts from psoriatic scales showed markedly elevated ribonuclease levels which could not be raised further by the addition of spermidine.
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PMID:Epidermal nucleases. III. The ribonucleases of human epidermis. 2 41

By sequential acid treatment, gel filtration and KM-cellulose sorption a 18--20-fold purified preparation of ribonuclease with a yield of 50--60% was obtained from the culture liquid filtrate of Actinomyces rimosus 994. The preparation had a high specific activity of 450,000--600,000 units/mg protein, contained 85--98% protein, insignificant amounts of carbohydrates and hydroxytetracycline, and no quantities of DNase, phosphomonoesterases, phosphodiesterase or proteases. In RNA degradation (preparation of the total yeast RNA of the Sigma Co.) optimal results were obtained at 50 degrees C and pH 7.0--7.2 in phosphate buffer and 7.6--8.0 IN Tris-HCl buffer. The preparation was stable at high temperatures (80--100 degrees) in the wide pH range and during storage in the lyophilized form and in buffer solutions. RNase effect was inhibited by zinc, copper, iron and cobalt cations and activated by beta-mercaptoethanol, citrate and EDTA. Protamine sulphate and urea in low concentrations (0.01% and 1--4 M, respectively) accelerated and in high concentrations (1% and 8 M, respectively) terminated the enzyme reaction. With respect to many properties RNase from Act. rimosus 994 was similar to extracellular RNases, produced by other actinomycetes and fungi.
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PMID:[Preparation of extracellular ribonuclease form Actinomyces rimosus 994]. 3 16

The synthesis of cytidylyu-(3,-5,)-cytidine (CpC) catalyzed by pancreatic ribonuclease at 23 degrees, 0 degrees, and -15 degrees C in Tris-HCl-buffer was compared with that in aqueous propan-2-0. The data obtained show that the increase in the yield of oligonucleotides in aqueous buffer at -15 degrees, observed earlier is rather a result of the concentration change in the reaction mixture caused by the freezing of water than by a temperature fall from 0 to -15 degrees. A 4-fold increase in the initial concentrations of the substrates and ribonuclease with respect to the concentrations used earlier leads to the yield of CC in a homogeneous solution at 0 degrees close to is yield found in the frozen mixture at -15 degrees.
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PMID:[Effect of temperature and concentrations of initial components on synthesis of internucleotide bond catalyzed by pancreatic ribonuclease]. 120 86

The ribonuclease and phosphodiesterase activities of rat liver plasma membranes, purified from the crude nuclear fraction by centrifugation in an A-XII zonal rotor and flotation, were examined and compared. The plasma membrane is responsible for between 65 and 90% of the phosphodiesterase activity of the cell and between 25 and 30% of the particulate ribonuclease activity measured at pH8.7 in the presence of 7.5mm-MgCl(2). Both enzymes were most active between pH8.5 and 8.9. Close to the pH optimum, both enzymes were more active in Tris buffer than in Bicine or glycine buffer. Both plasma-membrane phosphodiesterase and ribonuclease were strongly activated by Mg(2+), there being at least a 12-fold difference between the activity in the presence of Mg(2+) and of EDTA. There is, however, a difference in the response of the enzymes to Mg(2+) and EDTA in that the phosphodiesterase is fully activated by 1.0mm-MgCl(2) and fully inhibited by 1.0mm-EDTA, whereas the ribonuclease requires 7.5mm-MgCl(2) for full activation and 5mm-EDTA for full inhibition. Density-gradient centrifugation has indicated that on solubilization in Triton X-100 most of the ribonuclease activity is released into a small fragment of the same size as that containing the phosphodiesterase activity. The relationship between the two activities is discussed in view of these results.
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PMID:Alkaline ribonuclease and phosphodiesterase activity in rat liver plasma membranes. 435 77

Treatment of Spirillum itersonii with tris(hydroxymethyl)aminomethane (Tris)-ethylenediaminetetraacetate (EDTA) results in the quantitative release of alkaline phosphatase and ribonuclease into the surrounding medium. At the same time, about 90% of the total cellular soluble cytochrome c is liberated. This process occurs within 1 min of treatment at both 24 and 4 C. Release of these proteins by Tris-EDTA treatment is highly selective, since only 9% of the total cell protein is liberated, concomitantly with less than 5% ribonucleic acid, deoxyribonucleic acid, and malate dehydrogenase. Different sigmoidal curves are obtained for release of proteins as a function of EDTA concentration. The order of liberation with increasing EDTA is as follows: alkaline phosphatase, protein, soluble cytochrome c, and ribonuclease. Treatment of cells with Tris-EDTA under conditions which cause extensive loss of alkaline phosphatase, soluble cytochrome c, and ribonuclease results in cell death, with cessation of protein and ribonucleic acid synthesis. Cells treated with EDTA in phosphate buffer (in the absence of Tris) liberate a large portion of their soluble cytochrome c, but negligible amounts of alkaline phosphatase and ribonuclease. Addition of Tris to cells pretreated with phosphate-buffered EDTA releases high levels of alkaline phosphatase, but not ribonuclease. These results suggest that a common surface alteration is not solely responsible for release of periplasmic proteins. More likely, each protein of the periplasm is bound in an independent and specific manner.
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PMID:Selective release of proteins from Spirillum itersonii by tris (hydroxymethyl) aminomethane and ethylenediaminetetraacetate. 554 Oct 31

Polyspermine-ribonuclease (Mr approximately 17 000) and the enzyme transcriptase from Rauscher-leukaemia virus (Mr approximately 70 000) form a complex Mr approx. 160 000) such that the molar ratio of polyspermine-ribonuclease to reverse transcriptase is 5:1. The most favourable condition for complex-formation is in a solution consisting of 0.01 M-Tris/HCl buffer, pH 7.5, 0.25 M-KCl and 1 mM-Mn2+ at 37 degrees C. The association of the two enzymes retains full RNAase activity, but reverse-transcriptase activity is completely inhibited when ribonuclease-sensitive polymers such as (dG)12 x (rC)n or viral 70S RNA are used as primer templates.
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PMID:Complexing reverse transcriptase with polyspermine-ribonuclease. 616 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

We investigated two components of the polyacrylamide gel electrophoresis system used for sequencing DNA to improve the system for sequencing synthesized oligodeoxyribonucleotides containing positions of degeneracy. First, we varied the ratio of methylene-bis-acrylamide (MBA) to acrylamide from that commonly used in DNA sequencing gels (1% MBA:19% acrylamide). A moderate increase in the MBA:acrylamide ratio proves optimal when sequencing is used to confirm that a synthesized fragment contains equivalent stoichiometries of the different nucleotides at a given position of degeneracy. Such information is particularly important if the degenerate oligodeoxyribonucleotide preparation is to be employed as a hybridization probe. A further increase in the MBA:acrylamide ratio (3% MBA:19% acrylamide) produces a gel in which the sequence of an oligodeoxyribonucleotide mixture containing several positions of degeneracy can be read most easily. Increasing the MBA acrylamide ratio suppresses the effect of base composition on electrophoretic mobility of a fragment. Second, we investigated the use of a Tris-citrate buffer system in place of the standard Tris-borate system. We found the Tris-citrate system to be significantly more effective in preventing discontinuities in the banding pattern of the smaller fragments. Finally, we show that high MBA gels are also effective in resolving mixtures of oligoribonucleotides such as those produced by T1 ribonuclease digestion of small RNAs.
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PMID:Optimization of polyacrylamide gel electrophoresis conditions used for sequencing mixed oligodeoxyribonucleotides. 651 Jan 90

We have developed a rapid and sensitive method for detecting ribonuclease (RNAase). The method makes use of a RNA-Pyronine Y complex which has a different absorption spectrum from that of Pyronine Y alone. When the RNA is hydrolyzed by RNAase, the spectrum of the complex changes to that of unbound Pyronine Y. The resultant decrease in absorbance at 572 nm is linear for final RNAase concentrations ranging from 2 to 45 ng/ml. Optimal assay conditions were 11.5 micrograms/ml Pyronine Y, 0.56 mg/ml RNA, 80 mumol/ml Tris-HCl buffer, pH 7.8, and 2-45 ng/ml RNAase. The effect of complex concentration, pH, molarity and temperature upon the rate of the reaction were determined. The assay is applicable to crude cell-free extracts.
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PMID:A simple spectrophotometric method for the measurement of ribonuclease activity in biological fluids. 666 3

The seeds of Lagenaria siceraria (Family Cucurbitaceae) were extracted with water and the extract was lyophilized. The lyophilized extract was chromatographed on a DEAE-cellulose column in 10 mM Tris-HCl buffer (pH 7.2). The unadsorbed fraction was applied to an Affi-gel Blue gel column previously equilibrated with the same buffer. After removal of unadsorbed materials, the adsorbed proteins were eluted with 1.5 M NaCl in the Tris-HCl buffer. After dialysis the adsorbed fraction was loaded on a CM-Sepharose CL-6B column which had been equilibrated with and was eluted with the same buffer. After elution of unadsorbed proteins, the column was eluted with a gradient of 0-1 M NaCl in 10 mM Tris-HCl buffer (pH 7.2). The fraction eluting at about 0.55 M NaCl, which represented pure ribosome inactivating protein (RIP), inhibited cell-free translation in a rabbit reticulocyte system with an IC50 of 0.21 nM and exerted ribonuclease activity on yeast tRNA with an activity of 45 U/mg. The RIP was designated lagenin. It possessed a molecular weight of 20 kDa, smaller than the range of 26-32 kDa reported for other RIPs. The N-terminal sequence of lagenin exhibited a lesser extent of similarity to those of other Cucurbitaceae RIPs, characterized by a deletion of the first three amino acid residues and a replacement of the 4th (Phe), 17th (Phe), 18th (Ile) and 22nd (Arg) residues which are invariant in other RIPs.
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PMID:Lagenin, a novel ribosome-inactivating protein with ribonucleolytic activity from bottle gourd (Lagenaria siceraria) seeds. 1110 64


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