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:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Radioactive selenite reacts with purified human and goat immunoglobulins at acidic and neutral pH. The antigenic properties of the immunoglobulins are retained during the selenium labelling as shown by immunoelectrophoresis and autoradiography. Pepsin digests of 75Se-labelled IgG possess 75Se both in the (Fab')2 fraction and in the low molecular weight peptides derived from the Fc domains. Alpha-1-acid glycoprotein, ribonuclease, and lysozyme are also labelled by this procedure. Enhancement of 75Se incorporation by urea, guanidinium chloride, mercaptoethanol, sodium sulfite and carrier selenite is interpreted as an effect of destabilization of IgG disulfide bonds. Up to 1.4 g atoms Se per mol IgG have been incorporated. We assume that selenite is cleaving disulfides by a process akin to sulfitolysis. The lability of the isolated 75Se-labelled IgG to high concentrations of mercaptans and sulfite is consistent with this idea. These 75Se-labelled proteins may be useful in structure studies and radioimmunoassay.
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PMID:Reaction of selenium with immunoglobulin molecules. 1 84

220-MHz NMR was used to observe the titration behavior of the 5 histidine residues in porcine pancreatic ribonuclease (ribonucleate pyrimidine-nucleotido-2'-transferase (cyclizing), EC 3.1.4.22) and a derivative prepared by removal of 80% of the attached carbohydrate from this glycoprotein. Resonances due to histidine C-2 protons were observed over the full pH range for 3 of the residues; such resonances for the remaining 2 histidine residues broadened out as the pH was increased. Resonances due to histidine C-4 protons were also observed for 2 of the residues. The titration curves for both proteins were identical within experimental error. Resonances were assigned by comparison with histidine NMR titrations in ribonucleases from other species. Histidine 105, immediately adjacent to the site of attachment of a heterosaccharide side chain, has a C-2 proton chemical shift and pK that are insensitive to the large alteration in the bulk of the carbohydrate side chain. The chemical shifts of the C-2 proton of histidine 48 and of the C-4 proton of histidine 80, histidine residues that are close to one another and to another heterosaccharide side chain, show a similar insensitivity. The observations are direct evidence in support of the thesis that the heterosaccharides in porcine ribonuclease project away from the surface of the protein into the solution environment.
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PMID:A comparison by 220-MHz NMR of histidine hydronium ion titrations in porcine pancreatic ribonuclease and an extensively deglycosylated derivative. 3 80

Two antigenic variants of visna virus were isolated sequentially from a single sheep inoculated with a plaque-purified strain of virus designated 1514. The genetically stable variants, LV1-1 and LV1-4, are of two classes: LV1-1 is partially neutralized by antibody to the inoculum strain 1514, while LV1-4 is not neutralized by antibody to 1514. The genetic mechanism responsible for generating the antigenic variants was investigated by comparing the chymotryptic and tryptic maps of the envelope glycoprotein gp135 and core polypeptides (p30, p16, p14), and by comparing the pattern of large oligonucleotides produced by digestion of the RNAs by T1 ribonuclease. We show that only the peptide maps of gp135 differ among strains, that the number of peptide fragments altered is small and that gp135 is the polypeptide that elicits neutralizing antibody. The maps of the RNAs are identical. We conclude that mutation in the glycoprotein gene rather than recombination is more probably responsible for antigenic variation, and speculate on the special aspects of visna virus replication relevant to this phenomenon.
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PMID:Antigenic variation in visna virus. 22 3

The normal level of serum or plasma poly C-avid ribonuclease activity is 1047 +/- 247 U/mL. Serum levels increase proportionately with elevations in serum creatinine, reaching levels of 9,500-35,000 in patients undergoing dialysis. The levels can be normalised by successful renal transplantation but not by dialysis. Purified human urinary ribonuclease, a glycoprotein enzyme similar to the serum ribonuclease, was capable of: 1) inhibiting the incorporation of 3H-thymidine into mitogen-stimulated lymphocytes; 2) inhibiting the proliferation and growth of bone marrow red cell colonies; and 3) adversely affecting the growth and viability of precursor fat cells.
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PMID:Ribonuclease activity in renal failure: evidence for toxicity. 34 Nov 43

Two commonly used brands of reagent strip (dipsticks) were evlauated for their sensitivity to Bence-Jones and seven other urinary proteins. Both brands showed significant differences in sensitivity to albumin, glycoprotein, ribonuclease and lysozyme; both were most sensitive to albumin and least sensitive to globulin. Furthermore, their comparative sensitivities to these proteins also differed markedly. These differences in sensitivity could lead to underestimation of protein content in urine specimens. Tests on urines from patients with multiple myeloma showed that a negative urinary dipstick test result did not rule out the presence of the disease.
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PMID:Sensitivity of in vitro diagnostic dipstick tests to urinary protein. 64 3

Exposure of mycobacterial growth inhibitory factor (MycoIF) to trypsin, chymotrypsin, or neuraminidase decrease its ability to produce intracellular inhibition of mycobacterial growth within macrophages, suggesting that MycoIF was a glycoprotein. MycoIF was unaffected by deoxyribonuclease or ribonuclease. Supernatant fluids from antigenically stimulated H37Ra-immunized mouse spleen cells exposed to puromycin were unable to produce significant intracellular inhibition. This indicated that the presence of MycoIF activity in supernatant fluids required protein synthesis. The filtration of MycoIF-containing supernatant fluids on Sephadex G-150 demonstrated that significant MycoIF activity appeared only in those fractions which eluted on the downward side of the serum albumin peak. Based on protein standards filtered through the Sephadex gel, the molecular weight of MycoIF was calculated to be between 20,000 and 35,000. These calculations assumed that MycoIF is a globular protein. Attempts to purify MycoIF by anion exchange chromatography (diethylaminoethylcellulose) was not successful.
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PMID:Molecular weight and other characteristics of mycobacterial growth inhibitory factor produced by spleen cells obtained from mice immunized with viable attenuated mycobacterial cells. 81 60

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

We previously cloned, sequenced, and expressed two distinct mammalian Na+/H+ exchanger isoforms (NHE-1 and NHE-2). We report here the cloning of a composite cDNA which encodes a third mammalian isoform (NHE-3), which is expressed specifically in intestine and kidney. The protein deduced from the longest open reading frame of this composite sequence has 832 amino acids with a calculated Mr of 92,747. The hydrophobicity plot of NHE-3 is very similar to that of NHE-1 and NHE-2. NHE-3 is also predicted to have 10-12 membrane-spanning domains and a long cytoplasmic domain which contains putative protein kinase phosphorylation motifs. NHE-3 exhibits overall 41% amino acid identity with NHE-1. NHE-3 is likely a glycoprotein as it has one potential N-linked glycosylation site, which is conserved in all NHEs identified. Northern blot analysis of poly(A+) RNA isolated from rabbit ileum using NHE-3 cDNA as a probe hybridized to a single 5.4-kilobase transcript. More detailed tissue distribution of message was performed by ribonuclease protection assay. It was found that NHE-3 message is only expressed in intestine and kidney, with the kidney cortex having the most abundant message, followed by intestine and kidney medulla. In intestine, ileum and ascending colon have the same amount of message, with much lesser amounts in jejunum. The message is absent from duodenum and descending colon, which lack the neutral NaCl absorptive process. Thus, NHE-3 might be involved in Na+ absorption in intestinal and renal epithelial cells.
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PMID:Cloning and sequencing of a rabbit cDNA encoding an intestinal and kidney-specific Na+/H+ exchanger isoform (NHE-3). 137 92

It was found, in cell-free assays, that the Man8GlcNAc2 and Man7GlcNAc2 isomers having the mannose unit to which the glucose is added were glucosylated by the rat liver glucosyltransferase at 50 and 15%, respectively, of the rate of Man9GlcNAc2 glucosylation. This indicates that processing by endoplasmic reticulum mannosidases decreases the extent of glycoprotein glucosylation. All five different glycoproteins tested (bovine and porcine thyroglobulins, phytohemagglutinin, soybean agglutinin, and bovine pancreas ribonuclease B) were found to be poorly glucosylated or not glucosylated unless they were subjected to treatments that modified their native conformations. The effect of denaturation was not to expose the oligosaccharides but to make protein determinants, required for enzymatic activity, accessible to the glucosyltransferase because (a) cleavage of denatured glycoproteins by unspecific (Pronase) or specific (trypsin) proteases abolished their glucose acceptor capacities almost completely except when the tryptic peptides were held together by disulfide bonds and (b) high mannose oligosaccharides in native glycoproteins, although poorly glucosylated or not glucosylated, were accessible to macromolecular probes as concanavalin A-Sepharose, endo-beta-N-acetylglucosaminidase H, and jack bean alpha-mannosidase. In addition, denatured, endo-beta-N-acetylglucosaminidase H deglycosylated glycoproteins were found to be potent inhibitors of the glucosylation of denatured glycoproteins. It is suggested that in vivo only unfolded, partially folded, and malfolded glycoproteins are glucosylated and that glucosylation stops upon adoption of the correct conformation, a process that hides the protein determinants (possibly hydrophobic amino acids) from the glucosyltransferase.
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PMID:Recognition of the oligosaccharide and protein moieties of glycoproteins by the UDP-Glc:glycoprotein glucosyltransferase. 153 Oct 24

Differentiation inhibiting activity/leukemia inhibitory factor (DIA/LIF) is a glycoprotein that controls differentiation of pluripotential stem cells. Alternative transcription generates both diffusible and matrix-associated forms of DIA/LIF. Transcriptional analysis using a sensitive ribonuclease protection assay revealed that the two messages are expressed independently, consistent with the proposition that the two forms of DIA/LIF have distinct biological roles. DIA/LIF expression was found to be activated early during differentiation of embryonic stem (ES) cells, providing a mechanism for feedback regulation of stem cell renewal. Expression of DIA/LIF by mesenchymal cells was shown to be controlled in a paracrine manner by polypeptide regulatory factors. Specific expression of the two forms of DIA/LIF was also demonstrated in the egg cylinder-stage mouse embryo. The combination of cell type-specific and signal-specific regulation enables very precise control over DIA/LIF expression and may represent an important component of the regulatory networks that govern stem cell proliferation and differentiation during mammalian development.
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PMID:Developmentally programmed induction of differentiation inhibiting activity and the control of stem cell populations. 170 81


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