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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

After combined pancreatic and T(1) ribonuclease treatment of RNA, a characteristic series of products of the type A(n)N are obtained, where N can be any of the four ribonucleosides. Depending on whether phosphatase treatment is used before the addition of labelled phosphate at the 5'-terminus with bacteriophage phosphokinase, the labelled oligonucleotides obtained may or may not possess a phosphate group at the 3'- as well as the 5'-end. The behaviour of these characteristic products after electrophoresis on cellulose acetate strips followed by chromatography on polyethyleneimine-cellulose thin-layer plates was examined.
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PMID:The fractionation of adenosine-rich oligoribonucleotides on polyethyleneimine-cellulose. 482 12

GSH, but not GSSG, inhibits the reactivation by phosphate ion of ribonuclease activity inactivated by urea or guanidine. The effects of GSH are rather slow and pretreatment of ribonuclease with urea is a requisite for the inhibitory action of GSH on enzyme reactivation. GSH is more effective in urea than in guanidine and its action is greatly enhanced by EDTA. An optimum pH of about 9.0 was found for the inhibitory effect of GSH. Titration of the thiol groups formed after inactivation of ribonuclease by GSH strongly suggests that the reduction of only one disulphide linkage is involved. The reduction of this bond is sufficient to completely abolish the enzymic activity.
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PMID:Effect of glutathione on ribonuclease. 496 74

Group H streptococci (strain Challis) which are competent for transformation release a bacteriocin into liquid medium which is bacteriocidal for another group H streptococcus (strain Wicky). The streptocin (STH(1)) is resistant to treatment with deoxyribonuclease and ribonuclease but is sensitive to trypsin, phospholipase C, and alkaline phosphatase. Such enzyme sensitivity experiments indicate that the bacteriocin may be a complex molecule (protein and lipid) containing phosphate groups essential for activity. STH(1), which is readily distinguishable from competence factor and bacteriophage activity, appears to have no role in the initiation of the competent state in strain Wicky. The presence of this factor in Challis culture supernatant fluids indicates that a reevaluation of earlier studies performed with the Challis-Wicky transformation system may be necessary.
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PMID:Bacteriocin production by transformable group H streptococci. 508 61


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