Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate some synthetic catalysts that mimic ribonuclease, a quantitative assay has been developed that measures the number of phosphate diester bonds cleaved in a polymeric RNA substrate. This assay involves determining the number of 5'-oligonucleotide termini produced during the cleavage, using polyuridylic acid as the substrate. Samples withdrawn from the kinetic run are treated with venom exonuclease (phosphodiesterase I), and the increase in the concentration of uridine is determined by high-performance liquid chromatography. A related assay has been developed to monitor the catalyzed cleavage of the dinucleotide uridylyl(3'----5') uridine (UpU).
 ...
PMID:An assay to determine the kinetics of RNA cleavage. 258 71

A new and previously undescribed glycoprotein with a molecular weight of 43,000 has been isolated from human urine. This protein, designated GP43; copurified with ribonuclease, which has the same molecular weight, but ribonuclease activity was removed by passage through an affinity column of agarose-5'-(4-aminophenyl phosphoryl) uridine 2'(3') phosphate. GP43 contains about 5.9% neutral sugar, 2.3% hexosamine, and 1.6% sialic acid. A rabbit antibody to the purified GP43 reacted with human urine and serum as well as with the purified GP43. The genetic polymorphism of GP43 was then studied in desialylated human serum samples by urea-polyacrylamide gel isoelectric focusing, followed by immunoblotting with the specific antibody for GP43. Three common phenotypes, designated GP43 1, 1-2, and 2, were easily recognized using this technique and represented homozygosity or heterozygosity for two autosomal codominant alleles, GP43*1 and GP43/2. The frequencies of the GP43*1 and GP43*2 alleles in a Japanese population were 0.7683 and 0.2317, respectively.
 ...
PMID:Biochemical and genetic studies on GP43, a 43-kD glycoprotein detected immunologically in human urine and serum. 262 98

The organization of select proteins within ribonucleoprotein particles containing heterogeneous nuclear and uridine-rich small nuclear RNAs (hnRNP and UsnRNP respectively) was examined by chemical cross-linking and ribonuclease digestion using diagonal two dimensional PAGE and immunoblotting detection systems. Monoclonal antibodies specific for A2, C1 and C2 hnRNP proteins, detected these proteins at gel coordinates which suggested homotypic dimers and trimers of A2 and homotypic trimers, hexamers and larger multimers of C1 and C2. Ribonuclease digestion did not alter the cross-linking properties of hnRNP C1 and C2 proteins but did result in loss of A2 homotypic dimers and trimers. Blots simultaneously reacted with hnRNP specific monoclonal antibodies and autoimmune patient serum (RNP/Sm), or monoclonal antibodies reactive with the U1 snRNP specific 63 kDa protein and/or the UsnRNP common proteins B', B and D revealed no complexes which would indicate interactions between hnRNPs and UsnRNPs. The U1 UsnRNP specific 63 kDa protein appeared not to be cross-linked to UsnRNP common B', B and D proteins. The data also suggested that UsnRNP common protein D was cross-linkable to UsnRNP common proteins D', E and G but not to B' and B. The cross-linking properties of D were unaffected by ribonuclease digestion. In contrast, ribonuclease digestion resulted in an inability to cross-link select complexes containing either B' and B, or p63. The data suggest that both hnRNPs and UsnRNPs are comprised of RNA-dependent and RNA-independent protein-protein interactions.
 ...
PMID:Reversible chemical cross-linking and ribonuclease digestion analysis of the organization of proteins in ribonucleoprotein particles. 323 Dec 14

Differential scanning calorimetry (DSC) measurements were performed on the thermal denaturation of ribonuclease a and ribonuclease a complexed with an inhibitor, cytidine or uridine 3'-monophosphate, in sodium acetate buffered solutions. Thermal denaturation of the complex results in dissociation of the complex into denatured ribonuclease a and free inhibitor. Binding constants of the inhibitor to ribonuclease a were determined from the increase in the denaturation temperature of ribonuclease a in the complexed form and from the denaturation enthalpy of the complex. Binding enthalpies of the inhibitor to ribonuclease a were determined from the increase in the denaturation enthalpy of ribonuclease a complexed with the inhibitor. For the cytidine inhibitor in 0.2 M sodium acetate buffered solutions, the binding constants increase from 87 +/- 8 M-1 (pH 7.0) to 1410 +/- 54 M-1 (pH 5.0), while the binding enthalpies increase from 17 +/- 13 kJ mol-1 (pH 4.7) to 79 +/- 15 kJ mol-1 (pH 5.5). For the uridine inhibitor in 0.2 M sodium acetate buffered solutions, the binding constants increase from 104 +/- 1 M-1 (pH 7.0) to 402 +/- 7 M-1 (pH 5.5), while the binding enthalpies increase from 16 +/- 5 kJ mol-1 (pH 6.0) to 37 +/- 4 kJ mol-1 (pH 7.0). The binding constants and enthalpies of the cytidine inhibitor in 0.05 M sodium acetate buffered solutions increase respectively from 328 +/- 37 M-1 (pH 6.5) to 2200 +/- 364 M-1 (pH 5.5) and from 22 kJ mol-1 (pH 5.5) to 45 +/- 7 kJ mol-1 (pH 6.5). the denaturation transition cooperativities of the uncomplexed and complexed ribonuclease a were close to unity, indicating that the transition is two state with a stoichiometry of 1.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Interaction of cytidine 3'-monophosphate and uridine 3'-monophosphate with ribonuclease a at the denaturation temperature. 324 92

The activity of the endoribonuclease VI from Artemia is sensitive to several purine nucleotides. The enzyme is non-competitively inhibited by diguanosine tetraphosphate (Ki = 75 microM), a nucleotide abundant in Artemia encysted gastrulae and located in the same particulate fraction as the gastrular ribonuclease. Diguanosine triphosphate and diadenosine tetraphosphate are less efficient inhibitors (Ki congruent to 200 microM). The ribonuclease is non-competitively inhibited by 5'-AMP (Ki = 10 microM) and 5'-GMP (Ki = 50 microM) but is insensitive to the corresponding 5'-phosphates of cytosine and uridine. Other purine mononucleotides inhibit the enzyme activity less efficiently. The modulation of the enzyme activity by these nucleotides is discussed in relation with the changes in ribonuclease activity during early development of Artemia.
 ...
PMID:Diguanosine 5',5'''-P1,P4-tetraphosphate and other purine nucleotides inhibit endoribonuclease VI from Artemia. 341 43

A ribonuclease was isolated from serum-free supernatants of the human colon adenocarcinoma cell line HT-29. It was purified by cation-exchange and C18 reversed-phase high-performance liquid chromatography. The protein is basic, has a molecular weight of approximately 16,000, and has an amino acid composition that is significantly different from that of human pancreatic ribonuclease. The amino terminus is blocked, and the carboxyl-terminal residue is glycine. The catalytic properties of this ribonuclease resemble those of the pancreatic ribonucleases in numerous respects. Thus, it exhibits a pH optimum of approximately 6 for dinucleotide cleavage and employs a two-step mechanism in which transphosphorylation to a cyclic 2',3'-phosphate is followed by slower hydrolysis to produce a 3'-phosphate. It does not cleave NpN' substrates in which adenosine or guanosine is at the N position and prefers purines at the N' position. Like bovine ribonuclease A, the HT-29-derived ribonuclease is inactivated by reductive methylation or by treatment with iodoacetate at pH 5.5 and is strongly inhibited by the human placental ribonuclease inhibitor. However, in contrast, the tumor enzyme does not cleave CpN bonds at an appreciable rate and prefers poly(uridylic acid) as substrate 1000-fold over poly(cytidylic acid). It also hydrolyzes cytidine cyclic 2',3'-phosphate at least 100 times more slowly than uridine cyclic 2',3'-phosphate and is inhibited much less strongly by cytidine 2'-monophosphate than by uridine 2'-monophosphate. Other ribonucleases known to prefer poly(uridylic acid) were isolated both from human serum and from liver and were compared with the tumor enzyme. The physical, functional, and chromatographic properties of the serum ribonuclease are essentially identical with those of the tumor enzyme. The liver enzymes, however, differ markedly from the HT-29 ribonuclease. The potential utility of the tumor ribonuclease in the diagnosis of cancer is considered.
 ...
PMID:Isolation and characterization of a human colon carcinoma-secreted enzyme with pancreatic ribonuclease-like activity. 346 90

The stochastic boundary molecular dynamics method is used to study the structure, dynamics, and energetics of the solvated active site of bovine pancreatic ribonuclease A. Simulations of the native enzyme and of the enzyme complexed with the dinucleotide substrate CpA and the transition-state analog uridine vanadate are compared. Structural features and dynamical couplings for ribonuclease residues found in the simulation are consistent with experimental data. Water molecules, most of which are not observed in crystallographic studies, are shown to play an important role in the active site. Hydrogen bonding of residues with water molecules in the free enzyme is found to mimic the substrate-enzyme interactions of residues involved in binding. Networks of water stabilize the cluster of positively charged active site residues. Correlated fluctuations between the uridine vanadate complex and the distant lysine residues are mediated through water and may indicate a possible role for these residues in stabilizing the transition state.
 ...
PMID:Active site dynamics of ribonuclease. 386 34

Anti-hapten sera prepared in rabbits contain individual immunoglobulin species capable of binding several pairs of structurally diverse haptens A and B. (A = inosine, uridine, menadione, vitamin K(1), ribonuclease; B = 2,4-dinitrophenyl). In antisera against hapten A subjected to isoelectric focusing, there are many anti-A immunoglobulin species, but only a small proportion of these bind both A and B. When rabbits are primed with haptens A coupled to a carrier and then challenged with hapten B-carrier complex, there is an early restricted response of those species that bind both A and B. Later, immunoglobulins appear which bind B, but not A. These results suggest that multiple-binding antibodies exist in antisera against hapten and that such multiple binding is functional; i.e., that when two diverse haptens A and B bind to an immunoglobulin, both haptens may stimulate the cell-surface receptor to induce production of this immunoglobulin. Such phenomena may also provide a molecular basis for maturation of the immune response.
 ...
PMID:Antibodies with multiple binding functions. Induction of single immunoglobin species by structurally dissimilar haptens. 413 46

Kudo, Hajime (The Wistar Institute of Anatomy and Biology, Philadelphia, Pa.), and A. F. Graham. Synthesis of reovirus ribonucleic acid in L cells. J. Bacteriol. 90:936-945. 1965.-There is no inhibition of protein or deoxyribonucleic acid (DNA) synthesis in L cells infected with reovirus until the time that new virus starts to form about 8 hr after infection. At this time, both protein synthesis and DNA synthesis commence to be inhibited. Neither the synthesis of ribosomal ribonucleic acid (RNA) nor that of the rapidly labeled RNA of the cell nucleus is inhibited before 10 hr after infection. Actinomycin at a concentration of 0.5 mug/ml does not inhibit the formation of reovirus, although higher concentrations of the antibiotic do so. Pulse-labeling experiments with uridine-C(14) carried out in the presence of 0.5 mug/ml of actinomycin show that, at 6 to 8 hr after infection, two species of virus-specific RNA begin to form and increase in quantity as time goes on. One species is sensitive to ribonuclease action and the other is very resistant. The latter RNA is probably double-stranded viral progeny RNA, and it constitutes approximately 40% of the RNA formed up to 16 hr after infection. The function of the ribonuclease-sensitive RNA is not yet known. Synthesis of both species of RNA is inhibited by 5 mug/ml of actinomycin added at early times after infection. Added 6 to 8 hr after infection, when virus-specific RNA has already commenced to form, 5 mug/ml of actinomycin no longer inhibit the formation of either species of RNA.
 ...
PMID:Synthesis of reovirus ribonucleic acid in L cells. 415 5

In a number of mammalian cell strains nucleoli persisted through mitosis. This phenomenon was especially pronounced in several cell lines derived from Chinese hamster tissues. All the methods employed, including radioautography with tritiated uridine, cytochemical stains (methyl green-pyronin and azure B), fluorescent microscopy (coriphosphine O), ribonuclease digestion, and electron microscopy, demonstrated that the bodies identified as persistent nucleoli in the mitotic stages had the same characteristics as did the nucleoli in the interphase. Persistent nucleoli may attach to the chromosomes or may be free in the cytoplasm. In cells where no persistent nucleoli as such were noted, nucleolar material was observed to attach to the chromosomes in shapeless masses which moved with the chromosomes during anaphase. At least a portion of the nucleolar material was included in the daughter nuclei, presumably for immediate use for protein synthesis after cell division.
 ...
PMID:The nucleoli in mitotic divisions of mammalian cells in vitro. 422 82


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>