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)

Some physico-chemical properties, specificity and the character of action of rat liver nuclear ribonuclease are studied. The enzyme maximal activity was observed at pH 7.5--8.0, ionic strength 0.02--0.3, Mg2+ being necessary. Nuclease is an oligomer, having molecular weight is 160000--180000 daltons and containing separate associates. Purified enzyme is free of contaminating activities (polynucleotidephosphorylase, DNAse; 5'-nucleotidase, and alkaline phosphatases). It is shown to hydrolyse polyA and RNA for endonuclease type, degradation products being oligonucleotides terminating with 5'-phosphate and 3'-hydroxyl groups. RNAse hydrolyses all phosphodiester bonds in polynucleotides, developing no specificity to the nature of bases. Relative hydrolysis rate for different substrates decreased as follows: polyA greater than yeast RNA greater than polyC greater than polyU greater than 28S rRNA greater than greater than 18S rRNA greater than polyA-polyU. The enzyme may be classified as ribonucleate-5'-nucleotidehydrolase (EC 3.1.4.9.).
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PMID:[Nuclear ribonucleases and post-transcriptional changes of RNA. Specificity and other properties of rat liver nuclear endonuclease]. 1 31

Dialysis, gel-chromatography on Sephadex G-75 (superfine) and chromatography on sulphoethylcellulose give high yield (68 per cent) of 162-fold purified ribonuclease from cobra venom. In ion-exchange chromatography, ribonuclease is eluted in two fractions. The fraction with the highest specific activity has a molecular weight of 15900 and is homogeneous in 15 per cent polyacrilamide gel electrophoresis at pH 8.9. Electrophoresis at pH 4.3 reveals a minor fast component of this fraction which also exhibits a ribonuclease activity. Sulphoethylcellulose chromatography fairly separates cobra venom phosphodiesterase and 5'-nucleotidase eluted as a single fraction in gel chromatography.
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PMID:[Isolation of highly purified ribonuclease from cobra (Naja oxiana) venom]. 17 25

Pseudomonas aeruginosa (ATCC 9027) releases four periplasm-located enzymes, i.e., ribonuclease (EC 3.1.4.22; EC 3.1.4.23), alkaline phosphatase (EC 3.1.3.1), cyclic-2', 3'-phosphodiesterase (EC 3.1.4.d), and 5'-nucleotidase (EC 3.1.3.5) into the medium during growth. Ribonuclease and alkaline phosphatase are classed as enzymes which are readily extracted by osmotic shock and spheroplast formation whereas cyclic-2',3'-phosphodiesterase and 5'-nucleotidase are classed as enzymes which are not readily extracted by these procedures. In view of the relative ease of extraction of the former enzymes it is suggested that the lattter enzymes, cyclic-2',3'-phosphodiesterase and 5'-nucleotidase, are bound and located in the periplasm in a manner different to ribonuclease and alkaline phosphatase.
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PMID:The release and characterization of some periplasm-located enzymes of Pseudomona aeruginosa. 18 95

The activity of 5'-nucleotidase (EC 1.3.5), cyclic nucleotide phosphodiesterase (EC 2.1.4.17), non-specific phosphodiesterase (EC 3.1.4.1) and ribonuclease (EC 1.7.7.16)has been investigated in the seminal plasma of whole semen and in the secretions of the seminal vesicle, prostate and epididymis of the bull, boar, ram, stallion, jackass, rabbit and man. Bull seminal plasma showed the highest activity for 5'-nucleotidase, cyclic nucleotide phosphodiesterase and ribonuclease; in contrast, stallion and jackass semen were very poor in these enzymes. Ram, rabbit and boar seminal plasma showed intermediate levels for all enzymes studied. In the bull and ram, nucleolytic enzymes were found to be secreted by the seminal vesicles but in the boar, rabbit and stallion they originate mostly from the epididymis. In human seminal plasma all of the enzymes studied exhibited activity but the levels were generally lower than those recorded for the other species.
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PMID:The activity of some nucleolytic enzymes in semen and in the secretion of the male reproductive tract. 19 15

The enzymes from the venom of Heterometrus scaber, the indole compounds present and the toxic protein of the venom have been studied. The venom contains acid phosphatase, ribonuclease, 5'-nucleotidase, hyaluronidase, acetylcholine esterase and phospholipase. A. The indole compounds present in the venom have been identified as 5-hydroxytryptophan, tryptophan, serotonin and tryptamine, along with two unidentified indole compounds. The venom produces hyperglycaemia in sublethal doses and this has been found to be due to increased adrenaline secretion. The toxic protein of the venom has been obtained in a pure form by (NH4)2SO4 fractionation, followed by fractional precipitation with acetone and chromatography over DEAE-Sephadex. The toxic fraction has been found to be homogeneous on acrylamide gel electrophoresis. It is a glycoprotein (molecular weight 15 000) containing 1.74% glucosamine, 0.87% galactosamine, 0.313% sialic acid, 3.25% fucose and 0.45% of an unidentified neutral sugar. It did not show any enzyme activities, haemolytic activity or inhibition of succinate dehydrogenase activity but it produced hyperglycaemia in sublethal doses. The toxic level (intravenous administration in rats) was found to be 0.72 mg/kg body weight.
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PMID:Investigations on the venom of the South Indian scorpion Heterometrus scaber. 111 82

Pyrophosphate, p-nitrophenyl phosphate and a variety of pyrimidine and purine nucleotides are hydrolyzed by the solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. The pH optima (or ranges) for hydrolysis of substrates are 8.0 (pyrophosphate), 8.8 (p-nitrophenyl phosphate), 8.4-8.9 (nucleoside monophosphates), and 7.1-8.1 (nucleoside triphosphates); all substrates, with the exception of nucleoside triphosphates, have a higher affinity for the solubilized enzyme at pH 7.4 than at their optimal pH for hydrolysis. ATP is degraded completely by the enzyme preparation to adenosine and inorganic phosphate, but since neither ADP nor ATP accumulate in the incubation medium it is not known whether ATP hydrolysis involves the sequential hydrolysis of terminal phosphate groups. Isoelectric focusing and various chromatographic procedures (gel permeation, ion-exchange and hydrophobic interaction chromatography) fail to separate the alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities associated with the solubilized membrane preparation. Additionally, inhibitor studies indicate that only a single enzyme with low substrate specificity is involved in the hydrolysis of nucleotides, p-nitrophenyl phosphate, pyrophosphate and hexose phosphate esters. Purines and pyrimidines and their nucleosides interact with the active site, and in some instances activity of the enzyme is stimulated by an unknown mechanism.
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PMID:Nucleotide hydrolysis by solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. 613 88

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

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

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.
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PMID:Ophidian envenomation strategies and the role of purines. 1173 31


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