Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously demonstrated that (guanine-2-)-methyltransferase activity in extracts from 9,10-dimethyl-1,2-benzanthracene-induced rat mammary tumors differs from that of nonneoplastic mammary tissue. In this report, we explore further the nature of these differences by purification and characterization of the two major transfer RNA (tRNA) (guanine-2-)-methyltransferases from transplantable mammary tumors and proliferating mammary glands from pregnant rats. The position 10-specific (guanine-2-)-methyltransferases (2mGI) from proliferating rat mammary gland and mammary tumor were found to have similar properties with respect to molecular weight, substrate specificity, and elution behavior on ion-exchange columns. In addition, no tissue-specific differences were observed when the mammary tumor and mammary gland 2mGI activities were compared with those of purified rat liver enzyme. In contrast, the position 26-specific (guanine-2-)-methyltransferase (2mGII) from mammary tumors was seen to possess properties different from both the nontumorous mammary gland and liver enzyme. The tumor 2mGII activity showed unusual elution behavior on diethylaminoethyl-Sephadex, eluting along with the 2mGI activity. A small difference in molecular weight was detected between tumor and nontumorous 2mGII activities. Examination of the tumor enzyme in comparison with the well-characterized 2mGII from rat liver indicated that the mammary tumor 2mGII methylated a broader range of tRNA substrates. In particular, mature yeast phenylalanine-specific tRNA, which is methylated in vivo at all major eukaryotic methylation sites and should not be a substrate for eukaryotic methylating enzymes in vitro, could be methylated at low levels by the tumor enzyme. Two-dimensional electrophoretic fingerprint maps of T1 RNase-digested phenylalanine-specific tRNA from Escherichia coli methylated in vitro showed the presence of a methylated oligonucleotide which could not be correlated with normal sites of methylation on the tRNA. From these results, it appears that the mammary tumor 2mGII can methylate at some unusual site(s) on the tRNA molecule.
 ...
PMID:An unusual transfer RNA (guanine-2-)-methyltransferase from transplantable rat mammary tumors. 681 48

The degree to which amino acid sequence can be simplified with retention of conformational and functional properties has been investigated by semisynthesis using non-covalent fragment complexes of bovine pancreatic ribonuclease as test cases. Based on the ribonuclease S system, a set of synthetic model sequences was defined for the S-peptide (1-20) region which interacted productively with native S-protein (21-124). The most simple sequence, an eicosapeptide containing helix-favoring Ala residues at all positions except Glu 1 and 14, Phe 8, His 12, and Met 13, effected at least 15% of ribonuclease catalytic activity (versus native ribonuclease S) when added to S-protein in saturating amounts. The data for model S-peptides define an alpha-helical framework and specific side chains at positions 8, 12, and 13 as the core of sequence information necessary for S-peptide to effect a productive non-covalent complex with S-protein. Previous ribonuclease fragment studies also were used as a basis for making the productive, non-overlapping complex, (1-15):(21-111):(116-124). Addition of synthetic (1-15) and (116-124) to (21-111) led to a 3 degrees increase in Tm and 4% (versus ribonuclease A) catalytic activity. The three-fragment complex, with the beta-bend residues 112-115 deleted, exhibited significantly lower stability to thermal denaturation than did related two-fragment complexes. The potential use of three-fragment complexes related to the above is discussed for semi-synthetic sequence modeling concomitantly in the N- and C-terminal regions of ribonuclease.
 ...
PMID:Minimum information content and formation of interacting ribonuclease fragment complexes. 682 84

1. RNase Ms, a base non-specific RNase from Aspergillus saitoi was reduced and carboxymethylated (RCM-RNase Ms). RCM-RNase Ms was hydrolyzed with trypsin, and the trypsin digests were then treated with chymotrypsin. Trypsin digests were also treated with Staphylococcus protease and with chymotrypsin, separately. 2. By the analyses of the amino acid sequences of the peptides formed, the alignment of these peptides in RCM-RNase Ms was determined. 3. From the digest of heat-denatured RNase Ms with Bacillus subtilis protease, two peptides containing disulfide bridges were isolated. From the analysis of these two peptides, the locations of the bridges were determined. 4. The amino acid sequence of RNase Ms was compared with those of RNase T1 (Asp. oryzae, guanine specific), RNase U1 (Ustilago sphaerogena, guanine specific) and RNase U2 (Ustilago sphaerogena, purine specific). There are very similar sequences between these for RNases irrespective of their differences in base specificity. These were, in RNase Ms, tripeptide sequence containing His39 (Tyr-Pro-His), the tetrapeptide containing Glu57 (Glu-Tyr-Pro-Ile), the hexapeptide containing Arg76 (Asp-Arg-Val-Ile-Phe-Asp) and the hexapeptide containing His 91 (Ile-Thr-His-Thr-Gly-Ala). The other sequences common for all four RNases are Tyr67, Phe100, and Cys103 in RNase Ms. Since among these peptides His39, Glu57, His91, and Arg76 in RNase Ms corresponded to His40, Glu58, His92, and Arg77 in RNase T1 which are known to be involved in the active site of RNase T1, the possible role of these amino acids in the active site of RNase Ms is discussed. 5. The sequence similarity of RNase Ms to that of RNase T1 was about 60% and to those of RNase U1 and RNase U2 was about 30%. 6. The details of the experimental evidence used to elucidate the amino acid sequence of RNase Ms are described in the supplemental miniprint.
 ...
PMID:Primary structure of a minor ribonuclease from Aspergillus saitoi. 709 2

Investigations were carried out on the effects of phenylalanine loading on ribosomal protein phosphorylation in cerebral cortices of infant rats. Administration of L-phenylalanine intraperitoneally, in doses of 1 or 2 mg/g body wt., resulted within 30 min in a significant decrease in incorporation of radioactivity from intracisternally administered [32P]Pi into constitutive ribosomal proteins of the cerebral 40S subunit. This phenomenon was not accompanied by significant variations in 32P uptake into the cerebral cytosol. Incorporation of radioactivity into ribosomal proteins of the cerebral 60S subunit exhibited only minor variations under these circumstances. Alterations in the phosphorylation state of cerebral 40S ribosomal proteins induced by phenylalanine loading involved principally the S6 protein, which exists in multiple states of phosphorylation. The proportions of the more highly phosphorylated congeners of this protein were markedly decreased, as detected by two-dimensional electrophoretograms and autoradiographs of the cerebral 40S ribosomal proteins. Phenylalanine loading also altered the relative extent of phosphorylation of the S6 protein in cerebral polyribosomes and monoribosomes. In control animals, the specific radioactivity of 40S proteins in cerebral polyribosomes was five to ten times that of 40S proteins in the monoribosome population. At 1 h after phenylalanine administration, the specific radioactivities of 40S proteins in the two ribosome populations tended to approach equality. These alterations in ribosomal protein phosphorylation were accompanied by a decrease in the proportion of polyribosomes in purified ribosome preparations isolated from cerebral cortices of phenylalanine-treated infant rats. In animals given the higher dose of phenylalanine (2 mg/g body wt.), subsequent administration of a mixture of seven neutral amino acids, which resulted in partial recovery of polyribosomes, also tended to reverse the changes in ribosomal protein phosphorylation. Variations in the activities of ribonuclease enzymes in the cerebral cytosol were also observed under these conditions. Administration of phenylalanine increased the activities of cerebral ribonucleases, whereas subsequent treatment with the amino acid mixture partly reversed this effect. The results suggest that alterations in cerebral ribosomal protein phosphorylation, ribosome aggregation and ribosome function are interrelated in experimental hyperphenylalaninaemia.
 ...
PMID:Cerebral ribosomal protein phosphorylation in experimental hyperphenylalaninaemia. 747 57

The purpose of this study was to determine the mechanism by which contraction acutely accelerates the synthesis rate of the contractile protein myosin heavy chain (MHC). Laminin-adherent adult feline cardiocytes were maintained in a serum-free medium and induced to contract at 1 Hz via electrical field stimulation. Electrical stimulation of contraction accelerated rates of MHC synthesis 28%, p < 0.05 by 4 h as determined by incorporation of [3H]phenylalanine into MHC. MHC mRNA expression as measured by RNase protection was unchanged after 4 h of electrical stimulation. MHC mRNA levels in messenger ribonucleoprotein complexes and translating polysomes were examined by sucrose gradient fractionation. The relative percentage of polysomebound MHC mRNA was equal at 47% in both electrically stimulated and control cardiocytes. However, electrical stimulation of contraction resulted in a reproducible shift of MHC mRNA from smaller polysomes into larger polysomes, indicating an increased rate of initiation. This shift resulted in significant increases in MHC mRNA levels in the fractions containing the larger polysomes of electrically stimulated cardiocytes as compared with nonstimulated controls. These data indicate that the rate of MHC synthesis is accelerated in contracting cardiocytes via an increase in translational efficiency.
 ...
PMID:Contraction accelerates myosin heavy chain synthesis rates in adult cardiocytes by an increase in the rate of translational initiation. 766 17

A fluorescent tRNA derivative labeled at 3'-O position of the ultimate adenosine residue by reaction, under mild conditions, of tRNA with isatoic anhydride [3,1-benzoxazine-2,4(1H)-dione] was obtained. The labeling selectivity was determined by several criteria: digestion with RNase, followed by HPLC of the digest, produces only one labeled nucleoside, identified as 3'-O-anthraniloyladenosine; the ratio of the absorbance at 260 nm to 332 nm also suggests a 1:1 molar ratio between the nucleic acid and the fluorophore; finally, the incapacity of the labeled tRNA to be charged by the specific aminoacyltransferase further demonstrates the engagement of the 3'-O position. Although the 3'-O-anthraniloyl-labeled tRNA does not seem to be functionally active, as far as the aminoacyl charging activity is concerned, surprisingly we found that it is able to form the ternary complex with elongation factor Tu (EF-Tu) and GTP with an affinity consistently higher than uncharged tRNA. From fluorescence anisotropy measurements the ternary complex dissociation constant was estimated as 73 nM for Escherichia coli and 140 nM for yeast anthraniloyl-tRNA(Phe). These results may be interpreted in terms of the particular structure of the anthraniloyl group that makes the labeled tRNA similar to an aminoacyl-tRNA.
 ...
PMID:tRNA fluorescent labeling at 3' end inducing an aminoacyl-tRNA-like behavior. 768 46

Two distinct RNase P-like activities which cleave leader sequences from pre-tRNA molecules to give mature 5' ends have been identified in carrot suspension-culture cells. An Escherichia coli pre-tRNA(Phe) and a tobacco pre-tRNA(Tyr) were transcribed in vitro then used as substrates for processing reactions in a cell-free extract. The pre-tRNA(Tyr) transcript was used to establish optimal salt and divalent cation requirements for processing. Kinetic experiments were then carried out on both substrates to determine if 5' and 3' processing were ordered. Primer extension analysis of processing intermediates and stable products verified that an ammonium sulfate fraction of the extract was indeed capable of accurately processing the 5' ends of both pre-tRNAs. Subsequent fractionation of the 5' end-processing activity by chromatography on phosphocellulose revealed two distinct activities, eluting at 0.1 and 0.5 M KCI, when assayed with the tobacco pre-tRNA(Tyr) substrate. When the same fractions were assayed with the E. coli pre-tRNA(Phe), only the 0.1 M KCI fraction exhibited activity. Both of the active fraction display sensitivity to micrococcal nuclease (MN) and proteinase K indicating each is a ribonucleoprotein, a result not seen with other plant RNase Ps. Subsequent FPLC fractionation of the two activities using Mono Q and Mono S columns demonstrated that the two activities could be further distinguished on the basis of their chromatographic behavior.
 ...
PMID:Characterization and partial purification of two pre-tRNA 5'-processing activities from Daucus carrota (carrot) suspension cells. 774 55

Two Dutch patients with liver phosphorylase kinase (PhK) deficiency were studied for abnormalities in the PhK liver alpha (alpha L) subunit mRNA by reversed-transcribed-PCR (RT-PCR) and RNase protection assays. One patient, belonging to a large Dutch family that expresses X-linked liver PhK deficiency, had a C3614T mutation in the PhK alpha L coding sequence. The C3614T mutation leads to replacement of proline 1205 with leucine, which changes the composition of an amino acid region, containing amino acids 1195-1214 of the PhK alpha L subunit, that is highly conserved in different species. The patient showed normal levels of PhK alpha L mRNA. The second patient, from an unrelated family, was found to have a TCT (bp 419-421) deletion in the PhK alpha L coding sequence, resulting in a phenylalanine 141 deletion. The same deletion was found in the PhK alpha L coding sequence from lymphocytes of the patient's mother, together with a normal PhK alpha L coding sequence. The phenylalanine that is absent in the PhK alpha L coding sequence of the second patient is a highly conserved amino acid between species. Both the C3614T mutation and the TCT (bp 419-421) deletion were not found in a panel of 80 control X chromosomes. On the basis of these results, it is postulated that the mutations found are responsible for liver PhK deficiency in the two patients investigated.
 ...
PMID:X-linked liver phosphorylase kinase deficiency is associated with mutations in the human liver phosphorylase kinase alpha subunit. 784 71

A sequence-selective artificial ribonuclease was prepared by attaching ethylenediamine to the 5'-end of a DNA oligomer as the sequence-recognizing moiety. The hybrid, incorporating a 19-mer DNA which is complementary with the A44-A62 sequence of tRNA(Phe), hydrolyzed the tRNA selectively at the 3'-side of C63.
 ...
PMID:Selective hydrolysis of tRNA by ethylenediamine bound to a DNA oligomer. 788 43

High-performance liquid chromatography of carbohydrate materials on graphitized carbon columns (GCC) has some advantages over other types of chromatography. Oligosaccharides and glycopeptides with few amino acids are barely retained on reversed-phase columns even under high salt or low pH conditions, but can be retained effectively on a graphitized carbon column. Moreover, elution of GCC requires concentrations of organic solvents lower than that required for normal-phase columns. The usefulness of graphitized carbon columns is exemplified by the following results: (i) Man9GlcNAc2 with only Asn or Asn-Phe (derived from soybean agglutinin) was not retained by a C18 reversed-phase column, but could be separated on a GCC with a gradient of 10-45% CH3CN in 30 min. (ii) Ribonuclease B glycopeptides obtained by Pronase digestion could be separated on GCC with a gradient of 10-30% CH3CN, but they were not retained on a C18 reversed-phase column even with water as eluent. (iii) Oligosaccharides released from ribonuclease B by endo-beta-N-acetylglucosaminidase were separated from each other and peptides on GCC with a linear gradient of 10 mM NH4OH to 10 mM NH4OH-12.5% CH3CN in 50 min at 70 degrees C. Silica-based columns do not allow such an alkaline eluent. (iv) Chito-oligosaccharides (DP 1-9) are well separated within 40 min on GCC with a gradient (10 mM NH4OH-10 mM NH4OH with 25% CH3CN) at 50 degrees C. Chito-oligosaccharides could not be separated by high-performance anion exchange columns such as Carbopac PA-1.
 ...
PMID:High-performance liquid chromatography of glycopeptides and oligosaccharides on graphitized carbon columns. 808 79


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>