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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three ribonucleases, RNase I, RNase II and RNase III, were purified from the 109,000 X g supernate of detergent-treated Tetrahymena pyriformis strain W. RNases I and II act optimally at pH 5.5-6.0 and are inhibited by increasing concentrations of salts of monovalent cations. RNase III acts optimally at pH 7.5 and is activated 1.5-fold by millimolar concentrations of ZnSO4 and 5-fold by 50 mM KCl. RNases II and III are activated approximately 100% in the presence of 3 M and 5 M urea respectively. All enzymes are heat-sensitive and acid-resistant. They are endonucleases forming 2',3'-cyclic products. Their base specificity, as tested against ribosomal RNAs of known sequence, is as follows: RNase I hydrolyzes preferentially YpN and secondarily GpN bonds, RNase II is highly specific for RpN bonds, though the preparation can also hydrolyze the UpU sequence. Finally the principal targets of RNase III are YpR sequences and secondarily YpY sequences. A shorthand visualization of base specificity of nucleases in the form of right isosceles triangles is presented. The triangles are constructed by subdividing each of the two perpendicular sides in as many units as the maximum number of times the most abundant dinucleotide appears in all substrates employed and plotting the frequency of hydrolysis of each dinucleotide sequence by the enzyme under study. The proximity of each dinucleotide sequence to the hypotenuse or to one of the perpendicular sides is indicative of its susceptibility or resistance to the enzyme's action.
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PMID:Specificity and other properties of three ribonucleases of Tetrahymena pyriformis. 311 47

Multiple forms of ribonuclease II (EC 3.1.27.5) have been resolved from extracts of crude fractions of mouse liver by ion-exchange chromatography on phosphocellulose and gel permeation chromatography. The forms are designated 6S, 6L, 5S, 5L, 4S, 4L, 3S, 3L, 2, and 1 in increasing order of apparent cationic character. The forms fall into two series of apparent molecular weight. The small series increases from molecular weight equal to 9000 for form 1 to 14,000 for form 6S. The large series increases from molecular weight equal to 22,000 for form 2 to 44,000 for form 6L. All forms have pH-activity profiles with maxima near pH 7. Activity falls to no less than 30% of this maximum at pHs 5 and 8.5. Relative to the other forms, form 1 has a higher ratio of activity in the alkaline compared with acid pH range. Form 1 is found in the cytosolic, "light" particle, and "heavy" particle fractions. The other forms are largely restricted to the heavy particle fraction. In this fraction the proportion of total activity attributable to each form generally decreases in order from form 1 down to form 6. The results are accommodated by models in which one or more gene products give rise to multiple forms of ribonuclease II by processes involving dimerization and glycosylation.
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PMID:Multiple forms of ribonuclease II in mouse liver: relative sizes, subcellular distributions, and pH-activity profiles. 356 68

Thirty percent of RNase II (EC 3.1.27.5) is present in the cytosol of mouse liver where it exists in an inactive complex with a protein inhibitor. The remaining 70% of RNase II is active, soluble enzyme unassociated with inhibitor and is distributed in a ratio of 1.3 to 1 between the lumen of reticular elements and the interior of heavy particles. Although heavy particle RNase II resembles acid hydrolases in centrifugal behavior, in other tests including density shift experiments the resemblance is incomplete. In experiments employing lysis induced by L-amino acid methyl esters, RNase II activity is much more latent than the activity of the lysosomal marker, acid RNase. It is postulated that the heavy particle component of RNase II is contained in a secretory vesicle rather than in classic lysosomes.
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PMID:Multicompartmental distribution of ribonuclease II in mouse liver. 356 70

Because of evidence of an immunologic role for ribonuclease II (E.C. 3.1.27.5) in mammals, its presence in milk was further characterized to provide a basis for study of possible contributions of its activity to the health of infants. Isoenzymes of ribonuclease II were quantitatively resolved from milk samples as small as 1 ml or less by chromatography on phosphocellulose. Three isoenzymes detected in bovine milk were the previously reported ribonucleases A and B and a form termed ribonuclease II-1. These isoenzymes were in the ratio of 70:30:1. Form II-1 was unique in its inability to hydrolyze polycytidylate. Bovine colostrum contained 10 to 15 times more ribonuclease II-1 than does milk and three times more total ribonuclease II per unit volume. Human milk contains about 1% the concentration of ribonuclease II found in cows' milk. Ribonuclease II activity in milk was quite stable in the acidic conditions of whey production and during low heat treatments. However, most of its enzymatic activity was lost with high heat treatments. No commercially manufactured milk-based or soybean-based infant formula assayed contained nearly as much ribonuclease activity as either human or bovine milk.
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PMID:Ribonuclease activity and isoenzymes in raw and processed cows' milk and infant formulas. 366 41

RNase T, a nuclease thought to be involved in end-turnover of tRNA, has been purified about 4,000-fold from extracts of Escherichia coli. At this stage of purification, the enzyme was judged to be at least 95% pure based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native molecular weight of RNase T determined from gel filtration and sedimentation analyses is about 50,000, whereas the monomer molecular weight determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is 25,000, suggesting that the protein is an alpha 2 dimer. Purified RNase T is extremely sensitive to inactivation by oxidation, sulfhydryl group reagents, and temperature. The ribonuclease activity against tRNA-C-C-[14C]A is optimal at pH 8-9 in the presence of 2-5 mM MgCl2 and ionic strengths of less than 50mM. Although RNase T is highly specific for intact tRNA-C-C-A as a substrate and can hydrolyze all species in a mixed population of tRNA, it is inhibited by other RNAs, such as poly(A), rRNA, 5 S RNA, and tRNA-C-C. RNase T is an exoribonuclease which initiates attack at a free 3' terminus of tRNA and releases AMP; aminoacyl-tRNA is not a substrate. The role of RNase T in the end-turnover of tRNA and its possible involvement in other aspects of RNA metabolism are discussed.
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PMID:Purification and characterization of Escherichia coli RNase T. 388 94

To isolate mutants of Escherichia coli K-12 lacking endonuclease I activity (end), a method has been developed which detects, by differential methyl green staining, undegraded deoxyribonucleic acid (DNA) in colonies previously incubated in toluene. This procedure allows isolation of mutant strains in which DNA degradation is reduced. For half of these strains, this defect has been correlated with deficiencies of endonuclease I, ribonuclease I (rns), or ribonuclease II (rne) activities. The enzymatic deficiencies of the other strains remain unknown. An rne mutation is cotransducible with serA (which is located at 56 min on the genetic map). Most end mutations, called endA, are also cotransducible with serA and are located between serA and strA. One end mutation, called endB, is located between purE and trp (i.e., between 13 and 25 min on the genetic map).
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PMID:Mutants of Escherichia coli lacking endonuclease I, ribonuclease I, or ribonuclease II. 410 37

A number of "surface" enzymes of Escherichia coli (i.e., among those selectively released by osmotic shock) all displayed higher specific activities in extracts of minicells than in extracts of typical rod forms; these enzymes included alkaline phosphatase, cyclic phosphodiesterase, acid hexose monophosphatase, 5'-nucleotidase, and ribonuclease I. In addition, alkaline phosphatase, cyclic phosphodiesterase, and acid hexose monophosphatase were cytochemically localized to regions of minicell periplasm that resembled reactive polar enlargements of the periplasm in rod forms. In contrast, a number of "internal" cytoplasmic enzymes (inorganic pyrophosphatase, beta-galactosidase, glutamine synthetase, polynucleotide phosphorylase, and ribonuclease II) showed elevated or similar specific activities in extracts of rod forms versus extracts of minicells. A specific heat-labile inhibitor for 5'-nucleotidase, known to occur in the cytoplasm, also showed no enrichment in minicells. These findings indicate that the "surface" enzymes are segregated in vivo into the terminal minicell buds, possibly because these enzymes are concentrated in the polar enlargements of the periplasm in typical rod forms.
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PMID:Biochemical and cytochemical evidence for the polar concentration of periplasmic enzymes in a "minicell" strain of Escherichia coli. 431 25

The location of poly(A) sequences in the RNA of mammalian RNA-tumor viruses was determined by enzymatic analyses. The 56-64S viral genomic RNAs, the 20-40S viral subunit RNAs, and the 4-5S poly(A) sequences excised from these viral RNAs were subjected to either hydrolysis with a 3'-OH specific exoribonuclease from Ehrlich ascites tumor cells or phosphorolysis from the 3'-termini with polynucleotide phosphorylase from Micrococcus luteus. Purified adenosine-labeled poly(A) fragments, excised from genomic viral RNAs by RNase A and T(1) digestion, were hydrolyzed with the 3'-OH specific exoribonuclease for various periods of time. Poly(U) filter binding studies of the residual poly(A) indicated that 97% of the poly(A) fragments were hydrolyzed. Adenosine-labeled genomic and subunit viral RNAs and excised poly(A) fragments were phosphorolyzed from their 3'-termini for various periods of time with polynucleotide phosphorylase. The degree of phosphorolysis was monitored by poly(U) filter binding studies, and CCl(3)COOH insolubility and solubility determinations. There was an initial preferential rate of phosphorolysis of the poly(A) sequences of genomic and subunit viral RNAs as compared to the total adenosine-labeled viral RNAs. The data from these two different enzymatic mechanisms of action indicated conclusively that the poly(A) sequences were located at the 3'-termini of genomic and subunit viral RNAs.
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PMID:Polyriboadenylate sequences at the 3'-termini of ribonucleic acid obtained from mammalian leukemia and sarcoma viruses. 437 12

1. Two ribonucleases (aorta ribonuclease I and aorta ribonuclease II) from bovine aorta were purified 4611-fold and 667-fold respectively. Ethanolic precipitation, acid extraction, isoionic precipitation at pH3.5 and Bio-Rex 70 column chromatography were the methods employed. 2. Aorta ribonuclease I exhibited no deoxyribonuclease or alkaline phosphatase activity. 3. Aorta ribonuclease I appeared to be homogeneous when subjected to discontinuous gel electrophoresis. 4. Aorta ribonuclease II exhibited the same properties as aorta ribonuclease previously isolated. 5. The activities of the aorta ribonucleases and pancreatic ribonuclease on homopolymers and dinucleoside phosphates were compared. 6. Aorta ribonuclease I exhibited optimum pH7.5 and, under the assay conditions used, optimum temperature 60 degrees .
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PMID:Purification and characterization of bovine aorta ribonucleases. 534 73

A multiple mutant strain of Escherichia coli containing mutations affecting the exoribonucleases, RNase II, RNase D, and RNase BN, and also the endonuclease, RNase I, was constructed by P1-mediated transduction. Extracts of the mutant strain were lacking the aforementioned RNase activities. The multiple mutant displayed normal growth in both rich and minimal media at a variety of temperatures, recovered from starvation essentially as the wild-type parent, and could support the growth of a variety of bacteriophages. In addition, RNA synthesis was normal and no precursor RNA accumulation was observed. The properties of the mutant strain indicate that the three exoribonucleases are not essential for the viability of E. coli. The implications of these findings to our understanding of RNA processing and degradation are discussed.
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PMID:A multiple mutant of Escherichia coli lacking the exoribonucleases RNase II, RNase D, and RNase BN. 620 70


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