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)

A preparation of purified polyribosomes was isolated from wheat embryos germinating for 1 h with [3H]adenosine. Treatment of polyribosomes with pancreatic ribonuclease leads to the liberation of particles containing poly(A) sequences. Poly(A)-containing complexes show a heterogeneous distribution in the region 8--15 S. The ability of 8--15 S material to be absorbed to membrane filters under the conditions of low ionic strength and its sensitivity to pronase indicate that poly(A) sequences in polyribosomes are associated with protein. Analysis of this protein by electrophoresis in a polyacrylamide gel demonstrates the presence of two polypeptides with the molecular weights equal to 86,000 and 52,000.
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PMID:Proteins bound to poly(A) sequences of polyribosomes from germinating wheat embryos. 73 78

ATP : RNA adenyltransferase, purified from Escherichia coli, was used to add a series of adenosine residues to the 3'-end of MS2RNA. Incubations of the order of a few minutes at 37 degrees C were sufficient for synthesis of a short poly(A) chain that did not appreciably alter the hydrodynamic or electrophoretic properties of MS2 RNA. The size of the poly(A) tails was estimated by gel electrophoresis after prior hydrolysis of the primer RNA with pancreatic ribonuclease. These results were in good agreement with the values calculated on the basis of the relative amount of incorporated AMP. After the addition of a short poly(A) tail, approximately 50% of the treated material binds specifically to an oligo(dT)-cellulose column. The majority of the recovered poly(a)-containing RNA was still intact, as shown by analysis on polyacrylamide gel. After incubations beyond 6 min, slowly sedimenting material, also showing reduced electrophoretic mobility, was formed. Presumably this material corresponds to RNA chains to which long poly(A) tails are linked.
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PMID:The enzymic addition of poly(A) to the 3'-end of RNA using bacteriophage MS 2 RNA as a model system. 76 7

A method for the release of some proteins from Escherichia coli (MRE 600)ribosomes is described, avoiding extraction with denaturing reagents. High-salt-washed, 70-S ribosomes were treated with pancreatic ribonuclease which led to the release of 12 proteins of the larger ribosomal subunit. Separation of released protein was first attempted by gel filtration and by fractionation with (NH4)2SO4. The number and type of the released proteins were identified by sodium dodecyl sulphate-polyacrylamide gels and two-dimensional gel electrophoresis. The method should prove of use in the large scale purification of proteins L1, L7, and L25.
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PMID:Release of certain ribosomal proteins from 70-S Escherichia coli ribosomes by mild ribonuclease digestion. 76 34

We have studied the primary structure of 16S ribosomal RNA from Proteus vulgaris. The oligonucleotides containing methylated bases appeared to be the same as those of Escherichia coli, with one exception. We have also studied the base composition of the oligonucleotides obtained after T1 ribonuclease digestion of 16S RNA. On the basis both of their position on the fingerprint and of their pancreatic ribonuclease analyses, approximately 25 appeared to differ from those found in the E. coli T1 fingerprints. From the isolation of large fragments arising from the action of endogeneous endonucleases, we have concluded that the RNA sequences of both species are very similar. We have shown that the 5' and 3' extremities of 16S RNA are mostly conserved. It appears that the regions which are known to interact with ribosomal proteins in E. coli (particularly S8 and S15) are also less modified. It is noteworthy that the sequence modifications which have been observed are clustered and often correspond to regions of heterogeneity in E. coli 16S RNA.
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PMID:Comparative study of the 16S RNA's of Escherichia coli and Proteus vulgaris. 76 41

Kinetic properties of protein methylase II (S-adenosymethionine:protein O-methyltransferase, EC 2.1.1.24) which methylates (esterifies) the free carboxyl side chains of amino acids in proteins was studied using various polypeptides as methyl acceptor substrates. Bovine pancreatic ribonuclease, a model substrate for the enzyme, was subjected to specific cleavage by cyanogen bromide, trypsin, and performic acid oxidation. Several polypeptide fragments derived were then separated by molecular sieve chromatography on a column of Sephadex G-25. The method was found to be very simple and gave good yields. Km values for these polypeptides as well as a few other protein substrates were determined. While Km values for the isolated peptides range generally between 4.8 and 0.7 X 10-3 M, those of native bovine panreatic ribonuclease, luteinizing hormone, and follicle-stimulating hormone were determined to be 4.0 X 10-4, 5.0 X 10-5, and 0.77 X 10-5, respectively. Sites of enzymatic methylation of the native ribonuclease were also investigated. Although polypeptides derived from the C-terminal and N-terminal regions of the molecule were found to accept methyl groups, they were unable to under go enzymatic methylation when native molecule was used as the substrate indicating that within the native ribonuclease these regions are in a conformation which do not allow them to be methylated by protein methylase II under the present assay conditions.
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PMID:A comparison of kinetic parameters of polypeptide substrates for protein methylase II. 78 14

Trypsin, pepsin and subtilisin have been used as conformational probes for the structure of bovine seminal ribonuclease BS-1 by studying, under definite conditions, their effects on the seminal enzyme, a dimeric protein made up to two identical subunits; on bovine pancreatic monomeric ribonuclease A (EC 3.1.4.22) with a polypeptide chain homologous to that of the seminal ribonuclease subunit chain; and on a monomeric, active and stable derivative of seminal ribonuclease. The results show: (1) that the C-terminal regions of the pancreatic and the seminal proteins are very similar as they appear to fit in an identical way to the active site of pepsin; (2) that the resistance of the N-terminal region of ribonuclease BS-1 to subtilisin is not due to the dimeric structure of the protein, but to the conformation of this region, where an essential feature is the presence of a proline residue at position 19; (3) that the monomer of ribonuclease BS-1 is resistant to tryptic action only when bound to the partner monomer in the quaternary structure of the protein. This indicates that dissociation of the seminal ribonuclease makes some potentially susceptible susceptible bond or bonds available to trypsin either through a conformational change of the protein subunit, or by simply exposing the protein area hidden at the intersubunit interfaces.
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PMID:Proteolytic enzymes as structural probes for ribonuclease BS-1. 78 46

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 study of polysomal formation in the ts-136 thermo-sensitive yeast mutant indicates that ribosomes are assembled with an mRNA, which is in a structure tightly bound to membranes, and are then released into the soluble cytoplasmic fraction. This has been observed by studying the recruitment of ribosomes when glucose is added to glucose-starved cells and when transport of mRNA is permitted by shifting the mutant to the permissive temperature. A soluble cytoplasm and a fraction becoming soluble after sodium deoxycholate treatment of a rapidly sedimenting structure have been characterized. The former contains the majority of polysomes, free 80-S monomers and almost all of the ribosomal subunits. The latter fraction is composed of bound 80-S monomers and polysomes, but lacks ribosomal subunits. Treatment of the rapidly sedimenting structure with pancreatic ribonuclease produces the release of 80-S monomers, with EDTA the release of an equal proportion of both ribosomal subunits, and with sodium deoxycholate the release of 80-S monomers and polysomes. These findings are consistent with the assumption that bound ribosomes are assembled with an mRNA which is tightly bound to this rapidly sedimenting structure, presumably membranes. From the operational viewpoint this fraction is called the "membrane." During the process of polysomal formation ribosomes are recruited more rapidly in the "membranes" than in the soluble cytoplasm. Since "membranes" do not accumulate polysomes and contain only a small fraction of the total amount of ribosomes, the result is consistent with the assumption that either there is a higher turnover of bound versus free polysomes or bound polysomes are the precursors of free polysomes. The latter assumption is more likely since we have shown previously (a) that in yeast, transport is coupled with the translation of bound mRNA, (b) that this mRNA is tightly bound to a structure which sediments very rapidly and becomes soluble only after sodium deoxycholate treatment, and (c) when cycloheximide is added during the recruitment of ribosomes there is accumulation of membrane-bound ribosomes.
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PMID:Biogenesis of polysomes and transport of messenger RNA in yeast. 80 67

32P-Labeled MS2 RNA was partially digested with ribonuclease T1 (guanyloribonuclease; ribonucleate 3'-guanylo-oligonucleotidohydrolase; EC 3.1.4.8) or with epilson-carboxymethyl-lysine-41 pancreatic ribonuclease A (ribonucleate 3'-pyrimidino-oligonucleotidohydrolase; EC 3.1.4.22). A series of overlapping fragments was obtained which allowed the reconstruction of a 361-nucleotide-long 3'-terminal sequence. A unique reading frame could be deduced, which indicated that the replicase gene ends with a U-A-G termination signal and is followed by a 174-nucleotide-long untranslated segment.
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PMID:3'-Terminal nucletide sequence (n equals 361) of bacteriophage MS2 RNA. 80 66


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