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)

Protein synthesis, normally a light-dependent process in isolated mature chloroplasts of Euglena gracilis var. bacillaris will take place in darkness if ATP and Mg2+ (ATP/Mg) are supplied. Either 5 or 10 mM ATP plus 15 mM MgCl2 are optimal and rates equal to those in the light can be obtained. Since ATP and Mg2+ are not stoichiometrically related, and since the optimal Mg2+ concentration is similar to that which stabilizes chloroplast ribosomes in vitro, it is suggested that the chloroplast is freely permeable to Mg2+ under these conditions. Protein synthesis under these conditions is not inhibited appreciably by DCMU, FCCP, cycloheximide, or by the addition of ribonuclease, but is highly sensitive to chloramphenicol. Carbon dioxide fixation is also a light-dependent process in isolated mature chloroplasts from Euglena, but addition of ATP (5 mM) and fructose bisphosphate (5 mM) plus aldolase (1.0 unit/ml) (fructose-1,6-bisphosphate/aldolase) yields CO2 fixation rates in darkness that are 43% of those normally obtained in the light. Mg2+ higher than 1.0 mM (e.g., 16 mM) is somewhat inhibitory. Chlorophyll synthesis from 5-aminolevulinate in 36 h developing chloroplasts from Euglena is also light-dependent, but addition of ATP/Mg and fructose-1,6-bis-phosphate/aldolase in darkness brings about the accumulation of a compound having the same RF on chromatography as protochlorophyllide from Barley; a subsequent brief illumination of the chloroplasts converts this compound to a compound with the RF of chlorophyll. Thus Euglena chloroplasts supplied with appropriate additions can carry out protein synthesis, carbon dioxide fixation and most of chlorophyll synthesis in darkness. This versatility is appropriate in photosynthetic organelles isolated from photo-organotrophic cells.
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PMID:Synthetic abilities of Euglena chloroplasts in darkness. 392 91

The crystalline complex of pancreatic ribonuclease (RNase) with oligomers of d(pA)4 has been solved by x-ray diffraction methods and refined by standard procedures to a conventional crystallographic R factor of 0.22 at 2.5 angstrom resolution. The asymmetric unit is a complex of one RNase molecule associated with four d(pA)4 oligomers. Although the DNA in this complex is segmented, and therefore shows some discontinuities, it nevertheless traces a continuous path 12 nucleotides in length that passes through the active site cleft of the enzyme and over the surface of the protein. The DNA makes a series of eight to nine electrostatic bonds between its phosphate groups and lysine and arginine residues on the protein, as well as specific chemical interactions at the active site. The path described by the sequence of nucleotides is likely to be that taken by an extended polynucleotide chain when it is bound by the enzyme.
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PMID:The mechanism of binding of a polynucleotide chain to pancreatic ribonuclease. 396 3

Some of the enzymes and metabolites of the glycolytic pathway of an animal model for cystic fibrosis (the chronically reserpine-treated rat) were investigated. The activities of the enzymes phosphofructokinase (P less than 0.002), enolase (P less than 0.03), pyruvate kinase (P less than 0.005), and lactate dehydrogenase (P less than 0.009) were decreased whereas the activity of glycerol-3-phosphate dehydrogenase was unaffected in the submandibular glands of the treated animals. For metabolites, the reserpine treatment resulted in an increased concentration of glycogen (P less than 0.0002) and phosphoenolpyruvate (P less than 0.001) and a decreased concentration of pyruvate (P less than 0.005) and lactate (P less than 0.002) in the glands. The concentration of glucose and glycerate-2-phosphate was unaffected. The perchloric acid-soluble part of the proteins was also increased (P less than 0.0001) in the submandibular glands of the reserpine-treated animals, as was the activity of ribonuclease. These findings point to a disturbance in the metabolism of glucose and a possible acidosis in the submandibular glands of this animal model for cystic fibrosis.
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PMID:The chronically reserpinized rat: decreased glycolytic activity in the submandibular gland. 399 4

Analysis in a cell flow cytometer (Ortho Spectrum III, Ortho Inst.) of single cell suspensions from the bursa and thymus of 20-day embryos revealed two distinct cell clusters. The two clusters were less apparent after fixation of the cells in paraformaldehyde and assumed a comet-like appearance at 30 min fixation in ethyl alcohol (EA). The G (postmitotic), S [deoxyribonucleic acid (DNA) synthesis], and G2/M (premitotic and mitotic) phases of the life cycle were visualized in two cell flow cytometers (Ortho Spectrum III and FACS IV, Bectin Dickinson) after treating the cells with EA, ribonuclease (RNase), and propidium iodide (PI, a fluorescent dye). Bursal cell suspensions exposed to the EA-RNase-PI protocol and stored for 3 weeks in phosphate-buffered saline showed minor changes in the G1 coefficient of variation, G1, and S percentages, but marked changes in these parameters occurred after 6 weeks of storage. Thymic cells treated in a similar fashion could not be maintained for 3 weeks. Bursal and thymic cells may remain in the EA for one day and possibly as long as 7 days prior to preparing them for DNA life cycle analysis. Paraformaldehyde was not a satisfactory cell fixative for assessing a cell's DNA life cycle.
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PMID:Cell flow cytometry of fixed and unfixed bursal and thymic cells. 400 Oct 57

A method has been developed for the isolation of outer membranes from Acinetobacter sp. strain MJT/F5/199A. Washed cells were broken in a French press and, after deoxyribonuclease and ribonuclease treatment, removal of intact cells, and four washes in 20 mosmol phosphate buffer, pH 7.4, with centrifugation at 25,000 x g for 10 min, preparations of cell wall fragments from which almost all pieces of plasma membrane had been removed resulted. Treatment of the cell walls with lysozyme and further washing, in the presence of 20 mM MgCl(2), yielded preparations of outer membranes. Electron microscopy of freeze-etched preparations shows that a regular pattern of subunits is present on the outer surfaces of intact cells. After negative staining, these subunits are visible on isolated walls and outer membranes; they can be removed by brief treatment with papain. In section, the cell wall structure is that typical of gram-negative bacteria, but the subunits are not detectable on the surface of the outer membrane. The outer membrane retains the appearance of a "unit membrane" in the cell wall, isolated outer membrane, and papain-treated outer membrane fractions. Both cell walls and outer membranes contain a high percentage of protein (76 and 84%, respectively) and not more than 5% carbohydrate, of which glucose and galactose are constitutents. The outer membranes of this Acinetobacter thus differ in structure and composition from those of bacteria in the Enterobacteriaceae.
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PMID:Isolation of outer membranes with an ordered array of surface subunits from Acinetobacter. 412 37

1. The alanyl-s-RNA synthetase of tomato roots has been purified by ammonium sulphate precipitation, adsorption on calcium phosphate gel and DEAE-cellulose chromatography and its properties have been investigated. 2. Enzyme activity was measured by using the hydroxamate assay, the [(32)P]pyrophosphate-ATP-exchange assay and the [(14)C]alanyl-s-RNA assay. The purified enzyme was specific for l-alanine and was activated by Mg(2+) ions and to a smaller extent by Co(2+) and Mn(2+) ions. It was free from adenosine triphosphatase, pyrophosphatase and ribonuclease, and possessed a specific activity comparable with that of the most highly purified aminoacyl-s-RNA synthetases from animal and microbial systems. 3. The properties of the purified enzyme were similar in many respects to most other highly purified aminoacyl-s-RNA synthetases. It differed, however, in that the pH optimum of the hydroxamate assay was almost the same as that of the pyrophosphate-ATP-exchange assay and in requiring a high concentration of l-alanine for maximum activity (100mumoles/ml.). 4. The purified enzyme was not absolutely specific for tomato-root s-RNA; slight activity was also observed with yeast s-RNA. 5. The properties of this enzyme are fully consistent with the suggestion that the enzymic formation of alanyl-s-RNA proceeds via the intermediate formation of alanyl acyl-adenylate with the elimination of pyrophosphate from ATP. It remains to be shown the extent to which alanyl-s-RNA participates further in subsequent stages of protein synthesis in plants.
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PMID:The purification and properties of the alanyl-transfer ribonucleic acid synthetase of tomato roots. 428 91

The stable free radical 2,2,6, 6-tetramethyl-4-hydroxypiperidin-1-oxyl monophosphate has been synthesized; it binds to ribonuclease. The selective changes in the nuclear magnetic resonance spectrum of the enzyme produced by the free radical make it possible to define qualitatively the region of the enzyme to which it binds. The radical appears to occupy a site similar to that to which inorganic phosphate binds which is close to or within the active site of the enzyme.
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PMID:Noncovalent binding of a spin-labeled inhibitor to ribonuclease. 430 77

A protein kinase which is intimately associated with equine herpesvirus (equine abortion virus) was found by using adenosine triphosphate-gamma-(32)P as a phosphate donor and virus protein as an acceptor. Consistent demonstration of the activity requires prior removal of phosphohydrolase. The kinase activity requires Mg(2+), is not stimulated by cyclic adenosine monophosphate, but is enhanced by added protamine or arginine-rich histone. The labeled product is resistant to ribonuclease, deoxyribonuclease, and chloroform-methanol but is sensitive to Pronase. Other tests suggest that serine and threonine residues are the acceptor sites. In the in vitro reaction, the incorporation represents an average of approximately 4,500 phosphate residues per virion, and all 17 virus protein bands resolved by polyacrylamide gel electrophoresis appear to be labeled.
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PMID:Protein kinase activity in equine herpesvirus. 433 15

Brief exposure of Chinese hamster ovary cell monolayers prelabeled with [(32)P]phosphate and [(3)H]leucine to 1 mug/ml of trypsin under conditions in which cells remain fully viable causes the release of macromolecular (32)P and (3)H. Whereas ribonuclease treatment was found to affect markedly both the (32)P and (3)H radioactivity, Pronase treatment had little effect on the macromolecular (32)P. Treatment of cells prelabeled with [(3)H]glucosamine and [(32)P]phosphate with insolubilized papain also revealed a parallel release of macromolecular glucosamine together with ribonuclease-susceptible macromolecular phosphate. Lactoperoxidase-mediated radioiodination of surface components in cells prelabeled with [(32)P]phosphate revealed electrophoretic comigration between the (125)I and the (32)P that are removed from the cells by mild proteolysis. Growth of the cells in Bt(2)cAMP-testosterone altered the kinetics of release and nature of the macromolecular (32)P liberated by proteolysis.
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PMID:An "external" RNA removable from mammalian cells by mild proteolysis. 453 Oct 29

1. Bison ribonuclease was isolated from pancreas glands of Bison bison by acid extraction, (NH(4))(2)SO(4) fractionation, affinity chromatography on Sepharose-5'-(4-aminophenylphosphoryl)uridine 2',3'-phosphate and ion-exchange chromatography on Bio-Rex-70. 2. The selectivity of the affinity column towards bison ribonuclease in heterogeneous protein solutions was greatly improved by employing piperazine buffers at pH5.3, which decreased non-specific interactions of other proteins. Rapid desorption from the affinity column was obtained with sodium phosphate buffer (pH3). 3. Bison ribonuclease has a total amino acid content very similar to ox ribonuclease. Inactivation of bison ribonuclease with iodoacetic acid leads to the formation of 0.62 residues of pi-carboxymethylhistidine and 0.36 residues of tau-carboxymethylhistidine. The amino acid composition of peptides isolated from diagonal peptide ;maps' and also of peptides isolated after pH1.6 and 2.4 two-dimensional high-voltage electrophoresis of a digest of bison ribonuclease labelled with pyridoxal 5-phosphate indicates that there is complete homology between ox and bison ribonucleases. 4. The Schiff-base attachment site of pyridoxal 5-phosphate was identified as lysine-41 by NaBH(4) reduction followed by peptide isolation.
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PMID:The isolation and partial characterization of ribonuclease A from Bison bison. 477 70


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