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)

Preparations of yeast cell membranes can catalyse in vitro the N-acetyl-beta-D-glucosaminylation of the asparagine sequon at residues 34--36 of bovine pancreatic ribonuclease A. The relevant glycopeptides were isolated from tryptic hydrolysates of the glycosylated ribonuclease and analysed. The donor used was UDP-N-acetyl-D-glucosamine, although the mechanism of the transfer is unknown. Mn2+ ions at concentrations of 25 mM double the activity of the enzymic transfer.
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PMID:Glycosylation in vitro of an asparagine sequon catalysed by preparations of yeast cell membranes. 79 26

When the 23S RNA from E. Coli was pretreated for 1 h at 60 degrees in the presence of Mg++ and K+ and then subjected to T1 ribonuclease attack, resistant fragments were recovered from 3 regions of the molecule: region A (containing 470-500 nucleotides) located at the 5' end of 23S RNA, region B (containing 520-550 nucleotides) located at the 3' end and region C (containing 110-120 nucleotides) lying between region A and region B. The nucleotide sequences of the T1 and pancreatic ribonuclease digestion products from these 3 regions have been studied and in most cases determined. In the course of these studies, a certain number of abnormal nucleotides, which are not methylated, have been encountered. A low level of sequence heterogeneity was detected.
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PMID:Nucleotide sequences of the T1 and pancreatic ribonuclease digestion products from some large fragments of the 23S RNA of Escherichia coli. 80 6

The rRNA species from the total cytoplasmic, free and membrane-bound fractions of HeLa cells were compared. With the use of T1 ribonuclease and combined T1 ribonuclease plus pancreatic ribonuclease 'fingerprinting' procedures, no significant differences were found between the rRNA species from the different subcellular fractions.
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PMID:Comparison between the ribosomal ribonucleic acids from free and membrane-bound ribosomal fractions of HeLa cells. 82 Mar 34

Ribosomal protein S4 of Escherichia coli was bound to 16-S ribosomal RNAs from several bacterial species and the complexes digested with pancreatic ribonuclease in an effort to isolate heterologous RNA binding sites for protein S4. 16-S RNAs from Aeromonas punctata, Pseudomonas fluorescens and Vibrio cuneatus each gave rise to protected fragments whose electrophoretic mobility was 7S, i.e. similar to that of the fragment generated from E. coli 16-S RNA using the same conditions. No comparable fragment was obtained from 16-S RNA of either Bacillus subtilis or Bacillus stearothermophilus, if E. coli protein S4 was present prior to digestion. The protected 7-S RNA fragment from A. punctata and the subfragments obtained from it by gel electrophoresis under denaturing conditions were characterized further by fingerprinting and nucleotide sequence analysis. The sequence of many of the T1 ribonuclease oligonucleotides was obtained and compared to those from the E. coli 7-S fragment. This has permitted a tentative identification of the sequences of A. punctata 16-S RNA which are protected by E. coli protein S4, namely, the regions homologous to the E. coli sequence from section M through C''. The fingerprints of the protected 7-S fragments from both P. fluorescens and V. cuneatus were sufficiently different from that of the E. coli 7-S fragment that no conclusions regarding sequence homologies could be drawn.
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PMID:The binding site of Escherichia coli ribosomal protein S4 on 16-S ribosomal RNA from different bacterial species. 82 36

The sequences of amino acid residues 15-23 of red deer (Cervus elaphus) and roe deer (Capreolus capreolus) pancreatic ribonuclease and the identity of residue 99 in roe deer ribonuclease are corrected. Earlier results are explained by the cleavage of an Asp-Pro bond in both enzymes during the treatment with CNBr in 70% formic acid and by wrong interpretations of amino acid analyses. Proline residues, which occur at a number of positions in several mammalian ribonucleases, can be accommodated in a model of bovine ribonuclease S without disrupting the conformation of the main chain.
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PMID:Reinvestigation of the primary structures of red deer and roe deer pancreatic ribonuclease and proline sites in mammalian ribonucleases. 83 89

The lateral mobility of ribosomes bound to rough endoplasmic reticulum (RER) membranes was demonstrated under experimental conditions. High-salt-washed rough microsomes were treated with pancreatic ribonuclease (RNase) to cleave the mRNA of bound polyribosomes and allow the movement of individual bound ribosomesmfreeze-etch and thin-section electron microscopy demonstrated that, when rough microsomes were treated with RNase at 4 degrees C and then maintained at this temperature until fixation, the bound ribosomes retained their homogeneous distribution on the microsomal surface. However, when RNase-treated rough microsomes were brought to 24 degrees C, a temperature above the thermotropic phase transition of the microsomal phospholipids, bound ribosomes were no longer distributed homogeneously but, instead, formed large, tightly packed aggregates on the microsomal surface. Bound polyribosomes could also be aggregated by treating rough microsomes with antibodies raised against large ribosomal subunit proteins. In these experiments, extensive cross-linking of ribosomes from adjacent microsomes also occurred, and large ribosome-free membrane areas were produced. Sedimentation analysis in sucrose density gradients demonstrated that the RNase treatment did not release bound ribosomes from the membranes; however, the aggregated ribosomes remain capable of peptide bond synthesis and were released by puromycin. It is proposed that the formation of ribosomal aggregates on the microsomal surface results from the lateral displacement of ribosomes along with their attached binding sites, nascent polypeptide chains, and other associated membrane proteins; The inhibition of ribosome mobility after maintaining rough microsomes at 4 degrees C after RNase, or antibody, treatment suggests that the ribosome binding sites are integral membrane proteins and that their mobility is controlled by the fluidity of the RER membrane. Examination of the hydrophobic interior of microsomal membranes by the freeze-fracture technique revealed the presence of homogeneously distributed 105-A intramembrane particles in control rough microsomes. However, aggregation of ribosomes by RNase, or their removal by treatment with puromycin, led to a redistribution of the particles into large aggregates on the cytoplasmic fracture face, leaving large particle-free regions.
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PMID:Mobility of ribosomes bound to microsomal membranes. A freeze-etch and thin-section electron microscope study of the structure and fluidity of the rough endoplasmic reticulum. 83 67

Two ribonucleases were isolated from guinea-pig pancreas by extraction with 0.125 M sulfuric acid, precipitation with acetone and chromatography on carboxymethyl-cellulose. The amino acid sequences were determined from tryptic digests of the aminoethylated proteins. The tryptic peptides were positioned in the sequence by homology with other pancreatic ribonucleases. Both ribonucleases not only differ in the presence (ribonuclease B) or absence of carbohydrate (ribonuclease A), but also at 31 positions of the amino acid sequence. In guinea-pig ribonuclease B a leucine/proline heterogeneity was found at position 64. The carbohydrate in guinea-pig ribonuclease B is attached to asparagine residues at positions 21 and 34. The carbohydrate-free guinea-pig ribonuclease A possesses a recognition site for sugar attachment in the sequence Asn-Val-Ser (62-64).
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PMID:Guinea-pig pancreatic ribonucleases. Isolation, properties, primary structure and glycosidation. 86 24

The involvement of lysine residues in the active site of pancreatic ribonuclease has been investigated by assessing (a) the degree of substrate and substrate analogue protection of individual lysine residues against acetylation, and (b) the individual contribution of remaining unacetylated lysine residues to the total catalytic activity of the enzyme. Different substrate analogues (RNA digest, CMP, ATP, and pyrophosphate) were found to give different degrees of protection against acetylation with acetic anhydride. Instead of the expected specific protection of active site lysine residues such as lysine-7 and lysine-41, however, a general decrease in reactivity of all the lysines was observed when the substrate analogues were present during the acetylation. The fraction of enzymatic activity remaining in the protected samples was consistently greater than the fraction of any one lysine remaining unacetylated, and was found to correspond fairly well with the sum of the fractions of unacetylated lysine-7, lysine-41, and a third residue, tentatively assigned as lysine-66. This is consistent with other observations of ribonuclease which suggest that while no lysine residue interacts with substrate and substrate analogues in the formation of the Michaelis-Menten complex, a lysine amino group is required for catalysis. It is proposed that this lysine amino group can be supplied by any one of two or three lysine residues (7, 41, and 66) located close to the substrate binding site.
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PMID:The role of lysine in the action of bovine pancreatic ribonuclease A. 94 54

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2',3' hydroxyl end-groups is linked through the normal 3'--5' phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2',3 hydroxyl group is revealed. This structure could be a 5'-linked 5'-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3' end plus fragments that are not found after stepwise degradation. These fragments have a charge of --6 and --8 from pancreatic ribonuclease or --7 from ribonuclease T1 digestion. These charges are changed to --3.4 and --4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5' sequences m7G(5')ppp'AmpYpGp ... and m7G(5')pppAmpApGpYp.
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PMID:The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid. 94 25

Bison pancreatic ribonuclease was isolated by affinity chromatography. Thermolysin and tryptic digestion of denaturated protein, and subtilisin digestion of native protein yielded peptides, which were purified and submitted to amino acid analysis. These peptides, together with partial sequence data obtained by Stewart & Stevenson (16) overlap the entire amino acid sequence of bison ribonuclease. No differences with bovine ribonuclease were found, although there may be differences in state of amidation of some residues.
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PMID:Studies on the primary structure of bison pancreatic ribonuclease. 95 81


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