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

---

Query: EC:3.1.27.5 (RNase)
17,967 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.
...
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.).
...
PMID:The nucleotide sequences of the two glutamine transfer ribonucleic acids from Escherichia coli. 16 64

A 63-residue RNase A analog containing residues 26 to 35 then alanine, 41 to 59 and 73 to 84 then glycine, 100 to 110 then glycine, and 117 to 124 was synthesized by the solid phase method. The deletions comprised ordered (an alpha helix, parts of the beta sheet) and less ordered structures including 27 of the 56 residues invariant in mammalian ribonucleases. The synthetic 63-residue analog was cleaved from the insoluble support with liquid HF, reduced-reoxidized, fractionated by gel filtration, and purified further on an affinity column specific for the active site fold of RNase A. It had an activity of 8 to 14 per cent in the transphosphorylation step using poly(C) and poly(U) as substrates. It also had low synthetic and hydrolytic activity (0.2 per cent) and showed RNase A-like specificity toward the substrates tested. This indicated that all residues essential for substrate binding and catalysis were present and that their relative positions in the three-dimensional structure were probably very similar to those in native RNase A. Therefore, structure-function studies with the 63-residue RNase A analog should allow conclusions about the mode of action of the natural enzyme. As a first step in this direction, lysine 41 which is believed to be important for catalysis was replaced in the 63-residue analog by tyrosine or glutamine. The resulting (Tyr-41)- and (Gln 41)-63-residue analogs were also bound by the affinity column and had the same substrate specificity as native RNase A. They differed from each other, from the (Lys 41)-63-residue analog, and the 124-residue natural enzyme only with respect to the relative rates of the catalyzed reactions. Thus, lysine 41 does not seem to be essential for the functioning of RNase A.
...
PMID:Study of RNase A mechanism and folding by means of synthetic 63-residue analogs. 83 49

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.
...
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.
...
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).
...
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.
...
PMID:Transfer RNA lacking its 3' terminus is required for spermidine-dependent ribonuclease 65 activity in mouse FM3A cell extracts. 187 44

We review evidence for a pathway by which specific cytosolic proteins are targeted to lysosomes for degradation in cultured cells in response to serum withdrawal. This pathway is also activated by starvation in several rat tissues. The enhanced degradation is specific for a class of intracellular proteins containing peptide sequences related to residues 7 to 11 of ribonuclease A (RNase A). The amino acid sequence of this pentapeptide is lysine-phenylalanine-glutamate-arginine-glutamine, or, in single letter amino acid abbreviations, KFERQ. A heat shock protein of 73 kDa binds to such peptide regions in proteins and somehow mediates their transfer to lysosomes for degradation. The recent reconstitution of this lysosomal pathway of proteolysis in vitro should permit detailed mechanistic analysis of how proteins are directed to and translocated across lysosomal membranes.
...
PMID:Targeting of cytosolic proteins to lysosomes for degradation. 207 87

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.
...
PMID:Structure and size distribution of the androgen receptor mRNA in wild-type and Tfm/Y mutant mice. 217 22

A major challenge in genetics is identifying the basis of human heritable disease. We describe an "exon scanning" technique which surveys exons in genomic DNA for sequence alterations. By hybridizing genomic DNA to RNA probes derived from cDNAs, we can use RNase A to survey entire coding regions, comprising exons spread across extensive regions of genomic DNA, for mutations associated with genetic disease. Exon scanning of the beta-globin locus in the DNA of patients with 12 different hemoglobinopathies detected all of the culpable single base substitutions and deletions, but not single base insertions. Our analysis also revealed unsuspected polymorphisms and corrected a diagnosis originally based on hemoglobin electrophoresis. Exon scanning of the ornithine aminotransferase gene in a gyrate atrophy patient detected and localized a mutation in the sixth exon. Subsequent PCR amplification and sequencing characterized this as a missense mutation (proline----glutamine). Exon scanning of genomic DNA for sequence alterations, in combination with PCR amplification and sequencing, should be a generally useful strategy for evaluating suspect genes in disorders of unknown etiology, as well as for clinical diagnosis.
...
PMID:Detection of point mutations associated with genetic diseases by an exon scanning technique. 227 38


1 2 3 4 5 Next >>

---