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

The allosteric model for ribonuclease activity by Walker, Ralston & Darvey [(1975) Biochem.J. 147, 425--433; (1976) Biochem.J. 153, 329--337] involves the binding of a large number of molecules of substrate or substrate analogue to a series of allosteric sites on the enzyme. In the present paper, the nature of these allosteric interactions is investigated. The effects of ionic strength pH carbamoylation of lysine to homocitrulline and of deamidation of glutamine and asparagine on plots of velocity versus substrate concentration are examined and evidence is presented that the allosteric transition involves an electrostatic interaction between the negatively charged substrate molecules and the cationic groups on the enzyme.
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PMID:The nature of the allosteric interactions of ribonuclease and its ligands. 2 30

The nucleotide sequences of the two glutamine tRNA species in Escherichia coli K12 have been determined. Sufficient data was obtained to order unambiguously the products of complete RNase digestion of tRNA2Gln, and all but one oligonucleotide from tRNA1Gln. The sequence of tRNA1Gln was established by analogy with tRNA1Gln, as the two tRNAs are very similar, differing by only 7 residues out of 75. tRNA1Gln has the anticodon NUG, where N is a modified nucleotide which is likely to be a derivative of 2-thiouridine, and is specific for the codon CAA. tRNA1Gln has the anticodon CUG, and is specific for the codon CAG (Folk, W. R., and Yaniv, M. (1972) Nature 237, 165). The complete sequences of the tRNAGln species are: See journal for formula (Unique residues are enclosed in parentheses, with the residue in tRNA1Gln above that in tRNA2Gln.).
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PMID:The nucleotide sequences of the two glutamine transfer ribonucleic acids from Escherichia coli. 16 64

Pancreatic ribonucleases from several species (whitetail deer, roe deer, guinea pig, and arabian camel) exhibit more than one amino acid at particular positions in their amino acid sequences. Since these enzymes were isolated from pooled pancreas, the origin of this heterogeneity is not clear. The pancreatic ribonucleases from 11 individual arabian camels (Camelus dromedarius) have been investigated with respect to the lysine-glutamine heterogeneity at position 103 (Welling et al., 1975). Six ribonucleases showed only one basic band and five showed two bands after polyacrylamide gel electrophoresis, suggesting a gene frequency of about 0.75 for the Lys gene and about 0.25 for the Gln gene. The amino acid sequence of bactrian camel (Camelus bactrianus) ribonuclease isolated from individual pancreatic tissue was determined and compared with that of arabian camel ribonuclease. The only difference was observed at position 103. In the ribonucleases from two unrelated bactrian camels, only glutamine was observed at that position.
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PMID:Allelic polymorphism in arabian camel ribonuclease and the amino acid sequence of bactrian camel ribonuclease. 96 46

Dromedary (Camelus dromedarius) RNAase (ribonuclease) was isolated from pancreatic tissue by affinity chromatography. Peptides obtained by digestion with different proteolytic enzymes and CNBr were isolated by gel filtration, preparative high-voltage paper electrophoresis and paper chromatography. Peptides were sequenced by the dansyl-Edman method. All peptide bonds were overlapped by one or more peptides. The polypeptide chain consists of 123 amino acids. A deletion (position 39) was observed in an external loop of the polypeptide chain (residues 35-40), as was found earlier to horse RNAase (Scheffer & Beintema, 1974). A heterogeneity was found at position 103 (glutamine and lysine). Dromedary RNAase differs at 23-32% of the positions from all other pancreatic RNAases sequenced to date. In evolutionary terms this indicates that dromedary RNAase has evolved independently during the larger part of the evolution of the mammals. Detailed evidence for the sequence has been deposited as Supplementary Publication SUP 50046 (14 pages) at the British Library (Lending Division), Boston Spa, Wetherby, W. Yorks. LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem. J. (1975) 145, 5.
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PMID:The amino acid sequence of dromedary pancreatic ribonuclease. 116 57

Non-glycine residues with positive theta-angles have been identified in four proteins, barley serine proteinase inhibitor CI-2, bacterial ribonuclease (barnase) of Bacillus amyloliquefaciens, hen egg white lysozyme and a basic protein from barley seed (barwin) by use of nuclear magnetic resonance spectroscopy. By accurate measurements of the coupling constant (3)JHNHalpha and integration of the nuclear Overhauser HN-Halpha cross peak, positive theta-angles could be determined reliably to 60 degrees +/- 30 degrees, in full agreement with the crystal structures for lysozyme, barnase and serine proteinase inhibitor CI-2. The work emphasizes that positive theta-angles can also occur in non-glycine residues and in the four proteins, positive theta-angles have been observed for the residue types aspartic acid, asparagine, arginine, serine, glutamine, histidine, tyrosine, tryptophan and phenylalanine. The measured (3)JHNHalpha coupling constants and the intensity of the intraresidue HN-Halpha NOEs agree well with the solution structures of three of the proteins, using the existing parametrization of the Karplus curve (Pardi, A., Billeter, M. and Wuthrich, K. (1984) J. Mol. Biol., 180, 741-751; Ludvigsen, S. Andersen, K.V. and Poulsen, F.M. (1991) J Mol. Biol., 217, 731-736).
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PMID:Positive theta-angles in proteins by nuclear magnetic resonance spectroscopy. 139 67

A spermidine-dependent endoribonuclease (designated as RNase 65) activity requires both RNA and protein components (Nashimoto et al. (1991) Biochem. Biophs. Res. Comm. 176:1163-1169). In this study, we fractionated RNAs from mouse FM3A cell extracts and showed that an RNA fraction containing two major RNAs and two minor ones restored the micrococcal nuclease-inhibited RNase 65 activity. Partial sequences of these four RNA species were determined by chemical RNA sequencing. A sequence homology search revealed that the two major RNAs were glutamine tRNA lacking its 3' terminus, and that the two minor RNAs were initiator methionine tRNA and glycine tRNA lacking their 3' termini.
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PMID:Transfer RNA lacking its 3' terminus is required for spermidine-dependent ribonuclease 65 activity in mouse FM3A cell extracts. 187 44

Complementary DNA clones covering the coding region of the mouse androgen receptor (AR) were assembled by enzymatic amplification from testicular RNA and genomic DNA. The deduced amino acid sequence consists of 899 residues and departs from the rat sequence at 21 positions, 20 of which are in the amino-terminal trans-activation domain. A notable cluster of substitutions lies in the region of the long glutamine repeat at positions 174-195. The size heterogeneity of AR messengers suggested by previous blot hybridization experiments was examined by RNase protection analysis of sucrose gradient-fractionated poly(A) RNA from mouse liver. A predominant 10-kilobase long mRNA species was found to encode the AR, and a 3' noncoding portion longer than 5 kilobases was demonstrated by internal cleavage with RNase-H, followed by blot hybridization with a 3' probe. The sensitivity afforded by the use of homologous RNA probes in solution hybridizations allowed the demonstration in Tfm/Y mutant mice of an AR mRNA that covers the entire coding region, but is present at 10- to 20-fold lower levels than in normal animals. The detection of significant amounts of receptor messenger revives earlier suggestions of an AR protein in Tfm/Y mice and indicates, at variance with other conclusions, that the expression of this mutant AR is affected at a post-transcriptional level.
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PMID:Structure and size distribution of the androgen receptor mRNA in wild-type and Tfm/Y mutant mice. 217 22

cDNA clones coding for human plasma membrane Ca2+ pump isoforms have been isolated from a fetal skeletal muscle cDNA library. Compared with the sequence of a teratoma cDNA-encoded pump these clones specify isoforms that contain either 29- or 38-amino acid insertions within the calmodulin-binding region. Replacement of two basic arginine residues by an aspartic acid and a glutamine residue could influence the binding of calmodulin to these isoforms. RNase mapping shows that RNA species containing the 29-residue-encoding insertion are particularly abundant in skeletal muscles. The sequences coding for the insertions are present on a single 154-base-pair exon, as demonstrated by an analysis of the corresponding genomic region, and they are included in their respective mRNAs by alternative splicing involving the differential usage of two internal "cryptic" donor splice sites in the presence of a nearby canonical one. Inclusion of the complete 154-base-pair exon results in an mRNA coding for a pump protein with a shorter C-terminal amino acid sequence that lacks a consensus site for phosphorylation by the cAMP-dependent kinase. Exclusion, inclusion, or partial inclusion of the same exon can thus lead to the production of four different mRNAs from a single gene. When expressed as protein, these mRNAs encode Ca2+ pump isoforms that differ in their C-terminal regulatory domains.
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PMID:mRNAs for plasma membrane calcium pump isoforms differing in their regulatory domain are generated by alternative splicing that involves two internal donor sites in a single exon. 252 29

We report the DNA sequence and in vivo transcription start of pdxB, which encodes a protein required for de novo biosynthesis of pyridoxine (vitamin B6). The DNA sequence confirms results from previous minicell experiments showing that pdxB encodes a 41-kilodalton polypeptide. RNase T2 mapping of in vivo transcripts and corroborating experiments with promoter expression vector pKK232-8 demonstrated that the pdxB promoter shares its -10 region with an overlapping, divergent promoter. Thus, pdxB must be the first gene in the complex pdxB-hisT operon. The steady-state transcription level from these divergent promoters, which probably occlude each other, is approximately equal in bacteria growing in rich medium at 37 degrees C. The divergent transcript could encode a polypeptide whose amino-terminal domain is rich in proline and glutamine residues. Similarity searches of protein data bases revealed a significant number of amino acid matches between the pdxB gene product and D-3-phosphoglycerate dehydrogenase, which is encoded by serA and catalyzes the first step in the phosphorylated pathway of serine biosynthesis. FASTA and alignment score analyses indicated that PdxB and SerA are indeed homologs and share a common ancestor. The amino acid alignment between PdxB and SerA implies that PdxB is a 2-hydroxyacid dehydrogenase and suggests possible NAD+, substrate binding, and active sites of both enzymes. Furthermore, the fact that 4-hydroxythreonine, a probable intermediate in pyridoxine biosynthesis, is structurally related to serine strongly suggests that the pdxB gene product is erythronate-4-phosphate dehydrogenase. The homology between PdxB and SerA provides considerable support for Jensen's model of enzyme recruitment as the basis for the evolution of different biosynthetic pathways.
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PMID:Divergent transcription of pdxB and homology between the pdxB and serA gene products in Escherichia coli K-12. 268 Nov 52

Extensive 15N-NMR investigations of active-site amino acids were made possible by the solid-phase synthesis of the N-terminal pentadecapeptide of RNase A with selectively 15N-enriched amino acids. On complexation with S-protein a fully active RNase S' complex was obtained. The 15N resonances of the side chains of lysine-7 (N epsilon), glutamine-11 (N gamma), and histidine-12 (N pi, tau) were studied in the free synthetic peptide, in the RNase S' complex and in the nucleotide complexes RNase S' with 2'CMP, 3'CMP, and 5'AMP. The analysis of the 15N-1H couplings, the 15N line broadenings due to proton exchange, and the chemical shift values showed that, while the imidazole ring is directly involved in the peptide-protein interaction, the side chains of Lys-7 and Gln-11 do not contribute to this interaction. In the nucleotide complexes the resonances of His-12 and Gln-11 are shifted downfield. In the 2'CMP complex a doublet for the N tau signal of His-12 indicates a stable H bond between this nitrogen and the phosphate group of nucleotide. The other nucleotide influence the resonances of the imidazole group much less, possibly due to a slightly different orientation of the phosphate group. The downfield shift of the Gln-11 resonance indicates an interaction between the carbonyl oxygen of the amide group and the phosphate moiety of the nucleotide. The only observable effect of nucleotide complexation on the Lys-7 signal is line broadening due to reduced proton exchange. For comparison with the 15N-NMR titration curves of His-12 in RNase S' the 1H-NMR titration curves of RNase A were also recorded. Both shape and pK values were very similar for the 15N and the 1H titration curves. An extensive analysis of the protonation equilibria with several fitting models showed that a mutual interaction of the imidazole groups of the active-site histidines results in flat titration curves. The Hill plots of all resonances of the imidazole rings, including the 15N resonances, show a small inflection in the pH range 5.8-6.4. Since the existence of a diimidazole system is most likely in this pH range, the inflection could be interpreted as a disturbance of the mutual electrostatic interaction of the active-site histidines by a partial H-bond formation between the imidazole groups.
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PMID:15N- and 1H-NMR investigations of the active-site amino acids in semisynthetic RNase S' and RNase A. 283 66


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