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)

The complete amino acid sequence of ribonuclease (RNase MC) from the seeds of bitter gourd (Momordica charantia) has been determined. This has been achieved by the sequence analysis of peptides derived by enzymatic digestion with trypsin, lysylendopeptidase, and chymotrypsin, as well as by chemical cleavage with cyanogen bromide. The protein contains 191 amino acid residues and has a calculated molecular mass of 21,259 Da. Comparison of this sequence with sequences of the fungal RNases, RNase T2, and RNase Rh, revealed that there are highly conserved residues at positions 32-38 (TXHGLWP) and 81-92 (FWXHEWXKHGTC). Furthermore, the sequence of RNase MC was found to be homologous to those of Nicotiana alata S-glycoproteins involved in self-incompatibility sharing 41% identical residues.
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PMID:The complete amino acid sequence of ribonuclease from the seeds of bitter gourd (Momordica charantia). 189 1

The capacity of some Escherichia coli (E. coli) ribosomal proteins to bind to tRNA and to hydrolyse their aminoacylated derivatives has been analysed. The following results were obtained: (1) The basic proteins L2, L16 and L33 and S20 bound f[3H]Met-tRNA to a similar extent as the total proteins from 30 S (TP30) or 50 S (TP50) when tested by nitrocellulose filtration, in contrast to the more acidic proteins L7/L12 and S8. (2) The proteins of the peptidyltransferase centre, L2 and L16, showed no distinct specificity, binding various charged tRNAs from E. coli and Saccharomyces cerevisiae (S. cerevisiae). (3) A number of isolated ribosomal proteins hydrolysed aminoacyl-tRNA as assessed by trichloroacetic acid precipitation, in contrast to the TP30 and TP50. (4) The loss of radiolabel from Ac[14C]Phe-tRNA and from [14C]tRNA in the presence of these proteins could not be prevented by RNasin, a ribonuclease inhibitor, whereas that mediated by a sample of non-RNase-free bovine serum albumin was inhibited. (5) When double-labelled, Ac[3H]Phe-[14C]tRNA was incubated with L2 both radiolabels were lost, indicating that this potential candidate for a peptidyltransferase enzyme does not specifically cleave the ester bond between the aminoacyl residue and the tRNA.
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PMID:The complex between ribosomal proteins and aminoacyl-tRNA: the interactions and hydrolytic activities are not confined to the proteins L2 and L16 of Escherichia coli ribosomes. 218 27

We have isolated and sequenced cDNAs for S2- and S3-alleles of the self-incompatibility locus (S-locus) in Solanum chacoense Bitt., a wild potato species displaying gametophytic self-incompatibility. The S2- and S3-alleles encode pistil-specific proteins of 30 kDa and 31 kDa, respectively, which were previously identified based on cosegregation with their respective alleles in genetic crosses. The amino acid sequence homology between the S2- and S3-proteins is 41.5%. This high degree of sequence variability between alleles is a distinctive feature of the S-gene system. Of the 31 amino acid residues which were previously found to be conserved among three Nicotiana alata S-proteins (S2, S3, and S6) and two fungal ribonucleases (RNase T2 and RNase Rh), 27 are also conserved in the S2- and S3-proteins of S. chacoense. These residues include two histidines implicated in the active site of the RNase T2, six cysteines, four of which form disulfide bonds in RNase T2, and hydrophobic residues which might form the core structure of the protein. The finding that these residues are conserved among S-proteins with very divergent sequences suggests a functional role for the ribonuclease activity of the S-protein in gametophytic self-incompatibility.
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PMID:Cloning and sequencing of cDNAs encoding two self-incompatibility associated proteins in Solanum chacoense. 226 40

A cDNA encoding porcine ribonuclease inhibitor was used to express this protein in yeast under control of the PHO5 promoter. The recombinant protein was purified to homogeneity with a yield of 0.2 mg/g of yeast cells (wet weight) and was found to be indistinguishable from the inhibitor isolated from porcine liver on the basis of the following criteria: the amino acid composition, the number of free sulfhydryl groups, the molecular weight of the native and the denatured protein, peptide mapping, and amino acid sequence analysis of the N- and C-terminal regions of the protein. A simple method was developed for measuring accurately the slow, tight-biding kinetics of the inhibition of ribonuclease by ribonuclease inhibitor. From the dependence of the observed inhibition constant on the substrate concentration, it could be concluded that RI was competitive with the substrate UpA. The dependence of the observed association rate constant on the substrate concentration was consistent with a two-step mechanism in which the substrate only competed in the second (isomerization) step. The values for the inhibition constant for the inhibition of RNase by the recombinant inhibitor, 67 fM, the association rate constant, 1.5 x 10(8) M-1.s-1, and the dissociation rate constant, 8.3 x 10(-6) s-1, were in good agreement with those obtained for the porcine liver RNase inhibitor.
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PMID:Protein chemical and kinetic characterization of recombinant porcine ribonuclease inhibitor expressed in Saccharomyces cerevisiae. 227 59

Alkaline ribonuclease (RNase; EC 3.1.27.5) activities and 2',5'-oligoadenylate synthetase (2-5 AS; no EC no. assigned) activities in serum were measured in nine patients with hepatitis B e antigen-positive chronic hepatitis B before, during, and after treatment with recombinant human interferon alpha-2b for four weeks at daily doses ranging from 3 to 10 mega-units. Alkaline RNase activities in serum significantly increased from 65.8 +/- 9.5 units/L (mean +/- SD) to 84.3 +/- 11.9 units/L after the first week of therapy (P less than 0.001). (One unit of RNase activity is defined as that increasing the absorbance at 260 nm by 1.0 in 1 min). This increase persisted during and until two weeks after the end of the therapy, at which time the mean RNase activity in serum was still significantly increased (70.8 +/- 9.4 units/L, P less than 0.01). Before therapy, phosphocellulose chromatography of RNase showed five active peaks of enzyme activity, which were similar to that observed even when RNase activity increased immediately after therapy. There was a close correlation between RNase activities and the logarithm of 2-5 AS activities, measured simultaneously in each patient. We conclude that recombinant alpha-interferon therapy increases RNase activities in serum, associated with the increased 2-5 AS activities.
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PMID:Effects of recombinant leukocyte interferon on ribonuclease activities in serum in chronic hepatitis B. 235 34

A ribonuclease has been isolated from human spleen (RNase HS) by means of acid extraction, ammonium sulphate fractionation, successive column chromatographies on CM-cellulose, heparin-actigel, and poly(G)-agarose, and double gel-filtration on Sephadex G-75. The purified preparation was homogeneous as judged by SDS/PAGE. RNase HS was found to be a glycoprotein, containing three fucose, one mannose and five glucosamine residues/molecule, with a molecular mass of 17 kDa as determined by both SDS/PAGE and gel filtration. The catalytic properties and structural features, including its amino acid composition and the amino acid sequence of the N-terminal 35 residues, indicated that the enzyme was strictly related to nonsecretory RNase isolated from human urine and liver. In particular, the amino acid sequence of the N-terminal was identical with that of urine nonsecretory RNase and eosinophil-derived neurotoxin. Furthermore, analyses using three different antibodies specific to RNase HS, urine nonsecretory RNase and urine secretory RNase, indicated that RNase HS was not immunologically distinguishable from urine nonsecretory RNase, but clearly so from urine secretory RNase. However, the carbohydrate compositions of RNase HS and urine nonsecretory RNase were found to differ. It therefore remains to be resolved whether or not the tissue of origin of nonsecretory RNase in urine is the spleen.
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PMID:Purification and characterization of a ribonuclease from human spleen. Immunological and enzymological comparison with nonsecretory ribonuclease from human urine. 238 98

The applicability of ribonuclease cleavage at mismatches in RNA:DNA duplexes (RNase cleavage method) for determining nucleotide variant rates has been examined in a Japanese population. DNA segments of various lengths obtained from 4 different regions of a normal and 3 thalassemic cloned human beta-globin genes were inserted into transcription vectors. Sense and antisense RNA probes uniformly labeled with 32P were prepared. When RNA probes of 771 nucleotides (nt) or less were hybridized with cloned DNAs and the resulting duplexes were treated with a mixture of RNases A and T1, the length of products agreed with theoretical values. Twelve possible mismatches were examined. Since both sense and antisense probes were used, uncleavable mismatches such as G:T and G:G which were made from one combination of RNA and DNA strands could be converted to the cleavable C:A and C:C mismatches, respectively, by using the opposite combination. Deletions and insertions of 1 (G), 4 (TTCT), 5 (ATTTT) and 10 (ATTTTATTTT) nt were easily detected. A polymorphic substitution of T to C at position 666 of the second intervening sequence (IVS2-666) of the beta-globin gene was detected using genomic DNAs from cell lines established from the peripheral B lymphocytes of 59 unrelated Japanese from Hiroshima or those amplified by polymerase chain reaction (PCR). The frequency of the gene with C at the IVS2-666 (allele C) was 0.48 and that of the gene with T (allele T) was 0.52. The associations of the 2 alleles were in agreement with Hardy-Weinberg proportions. No contradiction to Mendelian inheritance was observed in the results obtained from 11 family studies. Two new polymorphic substitutions of C to A and A to T were detected at nucleotide positions 1789 and 1945 from the capping site, respectively, using genomic DNAs amplified by PCR. The feasibility of the RNase cleavage method combined with PCR for large-scale screening of variation in chromosomal DNA is discussed.
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PMID:Detection of deletions, insertions and single nucleotide substitutions in cloned beta-globin genes and new polymorphic nucleotide substitutions in beta-globin genes in a Japanese population using ribonuclease cleavage at mismatches in RNA:DNA duplexes. 238 39

The cytosolic untransformed molybdate-stabilized glucocorticoid-receptor complex from rat liver was eluted as a heterogenous peak containing two components with Stokes radii (Rs) of 8.3 nm and 7.1 nm when analyzed by size-exclusion HPLC even in the absence of molybdate. In contrast, the highly purified glucocorticoid receptor yielded a sharp symmetrical peak of Rs = 7.1 nm. We demonstrate that the 7.1-nm component could not result from a proteolytic degradation of the 8.3-nm receptor form. The same receptor heterogeneity was observed in thymus cytosol which contains less proteases than liver. After labeling with [3H]dexamethasone 21-mesylate and SDS/PAGE the same 94-kDa receptor band was revealed in both the 8.3-nm and 7.1-nm forms. Immunoblotting experiments showed that both the 94-kDa hormone-binding subunit and the 90-kDa heat-shock protein were present in the two different receptor forms. The 8.3-nm receptor form was converted to the 7.1-nm receptor form after treatment by ribonuclease A in the presence of molybdate and this effect was dose-dependent, being completely prevented by placental ribonuclease inhibitor (RNasin). In contrast, in the presence of molybdate, the 7.1-nm receptor form was ribonuclease-insensitive. Treatment of cytosol with RNase A in the absence of molybdate, partially shifted the untransformed receptor towards the 5.2-nm transformed receptor form. This effect was abolished by placental ribonuclease inhibitor. RNase S protein, an enzymatically inactive proteolytic fragment of RNase A, or S1 nuclease, which is specific for single-stranded nucleic acids, were ineffective when used instead of RNase A. In contrast, cobra venom endonuclease, which preferentially attacks double-stranded regions of small RNAs, caused a complete conversion of the 7-8-nm untransformed receptor to the 5.2-nm transformed receptor form. These results were not observed in the presence of molybdate. Addition of RNasin prior to heating cytosol in the absence of molybdate did not prevent the receptor from dissociating to the 5.2-nm form, suggesting that an endogenous RNase is not involved in the transformation process. The 7.1-nm receptor form was shifted to a 9.2-nm complex when incubated with an excess of GR 49 antireceptor antibody, whereas the 8.3-nm receptor form did not bind to the antibody.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:RNA binding to the untransformed glucocorticoid receptor. Sensitivity to substrate-specific ribonucleases and characterization of a ribonucleic acid associated with the purified receptor. 246 3

Double-stranded (ds) RNA and many viruses are inducers of interferon (IFN), the latter presumably because they contain, or can form, dsRNA. Concomitant with the induction of IFN in chicken embryo cells was the induction of a novel double-stranded ribonuclease (dsRNase), which was released into the medium and continued to accumulate long after IFN production ceased. Only avian cells (chicken, quail, turkey, or duck) expressed high levels of this dsRNase; mammalian, turtle, or fish cells did not. Production of the nuclease was inducer dose-dependent. Optimum pH and cation requirements distinguished it from other dsRNase activities. Degradation of dsRNA was endonucleolytic. Activity resided in a molecule of an Mr of approximately 34,500. Low levels of a single-stranded (ss) RNase activity were inseparable from the dsRNase. The role for a dsRNA-inducible dsRNase released from cells is unknown.
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PMID:Double-stranded ribonuclease coinduced with interferon. 247 Dec 68

The human MDR1 gene encoding P-glycoprotein, an energy-dependent drug-efflux pump, was initially isolated from a multidrug-resistant KB carcinoma cell. When a 3 kb genomic sequence isolated from normal human tissue including the major downstream promoter and the first and second exons of the MDR1 gene was compared to the equivalent fragment from KB cells, the MDR1 gene from KB carcinoma cells was found to have a point mutation in the first exon. Although this mutation does not affect the downstream promoter sequence or the coding sequence of the MDR1 gene, it creates a single base mismatch between the 5' KB genomic fragment previously used for RNase protection analysis of MDR1 RNA expression in normal tissues and thereby reduces the sensitivity of this assay. Using the DNA fragment from normal tissues rather than KB cells, we have reanalyzed MDR1 mRNA levels in 12 renal carcinomas and 4 colon adenocarcinomas. By this RNase protection assay, MDR1 RNA levels are as high in these tumors as in the multidrug-resistant cell line, KB-8-5. The ribonuclease protection assay indicated that the major downstream promoter was mainly used in these clinical samples including two samples of RNA from metastatic renal cancer. This assay appears to be a very sensitive and specific assay for detecting MDR1 mRNA levels and mRNA initiation sites in clinical samples.
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PMID:Detection of multidrug resistance (MDR1) gene RNA expression in human tumors by a sensitive ribonuclease protection assay. 248 65


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