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)

Red kangaroo (Macropus rufus) ribonuclease was isolated from pancreatic tissue by affinity chromatography. The amino acid sequence was determined by automatic sequencing of overlapping large fragments and by analysis of shorter peptides obtained by digestion with a number of proteolytic enzymes. The polypeptide chain consists of 122 amino acid residues. Compared to other ribonucleases, the N-terminal residue and residue 114 are deleted. In other pancreatic ribonucleases position 114 is occupied by a cis proline residue in an external loop at the surface of the molecule. Other remarkable substitutions are the presence of a tyrosine residue at position 123 instead of a serine which forms a hydrogen bond with the pyrimidine ring of a nucleotide substrate, and a number of hydrophobichydrophilic interchanges in the sequence 51-55, which forms part of an alpha-helix in bovine ribonuclease and exhibits few substitutions in the placental mammals. Kangaroo ribonuclease contains no carbohydrate, although the enzyme possesses a recognition site for carbohydrate attachment in the sequence Asn-Val-Thr (62-64). The enzyme differs at about 35-40% of the positions from all other mammalian pancreatic ribonucleases sequenced to date, which is in agreement with the early divergence between the marsupials and the placental mammals. From fragmentary data a tentative sequence of red-necked wallaby (Macropus rufogriseus) pancreatic ribonuclease has been derived. Eight differences with the kangaroo sequence were found.
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PMID:The amino-acid sequence of kangaroo pancreatic ribonuclease. 65 39

Two ribonucleases were isolated from guinea-pig pancreas by extraction with 0.125 M sulfuric acid, precipitation with acetone and chromatography on carboxymethyl-cellulose. The amino acid sequences were determined from tryptic digests of the aminoethylated proteins. The tryptic peptides were positioned in the sequence by homology with other pancreatic ribonucleases. Both ribonucleases not only differ in the presence (ribonuclease B) or absence of carbohydrate (ribonuclease A), but also at 31 positions of the amino acid sequence. In guinea-pig ribonuclease B a leucine/proline heterogeneity was found at position 64. The carbohydrate in guinea-pig ribonuclease B is attached to asparagine residues at positions 21 and 34. The carbohydrate-free guinea-pig ribonuclease A possesses a recognition site for sugar attachment in the sequence Asn-Val-Ser (62-64).
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PMID:Guinea-pig pancreatic ribonucleases. Isolation, properties, primary structure and glycosidation. 86 24

Pancreatic RNAase (ribonuclease) from the pike whale (lesser rorqual, Balaenoptera acutorostrata) was isolated by affinity chromatography. The protein was digested with different proteolytic enzymes. Peptides were isolated by gel filtration, preparative high-voltage paper electrophoresis and paper chromatography. The amino acid sequence of peptides was determined by the dansyl-Edman method. Although we do not have an amino acid composition for the whole protein, all peptide bonds were overlapped by one or more peptides. Residues 85-96 are bridged by a peptide of unstaisfactory composition and the sequence here depends, at least in part, on homology for its confirmation. Another region in which a similar situation obtains is residues 39-40. This pancreatic RNAase differs at 24-33% of the positions from all other mammalian pancreatic RNAases sequenced to date, except for pig RNAase, from which it differs by 19%. This indicates that whale RNAase has evolved independently during the larger part of the evolution of the mammals. Lesser-rorqual pancreatic RNAase is partially glycosidated (30%) at asparagine-76 in an Asn-Ser-Thr sequence (residues 76-78). Pig RNAase also has carbohydrate attached to asparagine-76 and is identical with lesser-rorqual RNAase in residues 76-98. Detailed evidence for the sequence has been deposited as Supplementary Publication SUP 50066 (11 pages) at the British Library Lending Division, Boston Spa, Wetherby, W. Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms ginen in Biochem. J. (1976) 135, 5.
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PMID:The amino acid sequence of pike-whale (lesser-rorqual) pancreatic ribonuclease. 96 70

Serum contains a sugar transferase which is able to catalyse the glycosylation in vitro of the asparagine residue present in the sequence Asn.Leu.Thr in bovine pancreatic ribonuclease. UDP-2-Acetamido-2-deoxy-D-glucose (UDP-N-acetyl-D-glucosamine) acts as a donor, although the mechanism of the transfer is unexplored. Spermidine and Mn2+, as well as CDP-choline, can act as activators for the reaction. Monoglycosylated ribonuclease (ribonuclease-GlcNAc) has been separated (23% yield) from unreacted ribonuclease A by affinity chromatography on a column of wheat-germ agglutinin bound to Sepharose, and characterised. A possible reason for the presence of the enzyme in serum is suggested.
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PMID:UDP-N-acetyl-D-glucosamine-asparagine sequon N-acetyl-beta-D-glucosaminyl-transferase-activity in human serum. 98 74

The COOH-terminal tetradecapeptide of ribonuclease A, Glu-Gly-Asn-Pro-Tyr-Val-Pro-Val-His-Phe-Asp-Ala-Ser-Val, and two analogs, [Ser(Me)-123]-RNase 111-124 and [Ala-123]-RNase 111-124, were synthesized by the solid phase method and were purified to chromatographic and electrophoretic homogeneity. Methods are described for the hydrolysis and quantitative amino acid analysis of peptides containing O-methylserine. The peptides were combined noncovalently with RNase 1-118 and examined for ability to regenerate enzymatic activity in the presence of the substrates C greater than p, U greater than p, poly(C) poly(U), and poly(AF). The dissociation constants of the peptide-protein complexes, and the Michaelis constants for C greater than p and U greater than p with the reconstituted enzymes were determined. The data were used to test hypotheses, drawn from x-ray crystallographic and other studies, for the role of serine-123 in the binding of substrates by ribonuclease. It was found that Ser-123- and Ala-123-containing peptides were equally active for the hydrolysis step when measured with C greater than p as substrate and for the transphosphorylation step as measured in the assays with poly(C). The serine and alanine analogs were also equally active for the transphosphorylation step when poly AF was the substrate. With U greater than p as substrate the alanine analog was 4 times less active than the serine derivative and with poly U it was 2 times less active. The semisynthetic enzyme composed of RNase 1-118 and [Ala-123]-RNase 111-124, therefore, shows appreciable selectivity for substrates containing cytosine. It was concluded that a hydrogen bond between the hydroxyl of serine-123 and the C4 amino group of cytidine or the C-7 amino group of formycin is not important for substrate binding and catalytic activity. In contrast, the hydrogen bond between the hydroxyl of serine 123 and the C-4 carbonyl oxygen of uridine contributes significantly to substrate binding and catalytic activity. The data with serine-O-methyl ether at position 123 in the tetradecapeptide were less clear because it was difficult to separate steric effects from the contributions of hydrogen bonding. Substrate binding to ribonuclease was rationalized in terms of a binding energy equivalent to a total of two hydrogen bonds per pyrimidine.
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PMID:The role of serine-123 in the activity and specificity of ribonuclease. Reactivation of ribonuclease 1-118 by the synthetic COOH-terminal tetradecapeptide, ribonuclease 111-124, and its O-methylserine and alanine analogs. 111 2

1. RNAase (ribonuclease) U2, a purine-specific RNAase, was reduced, aminoethylated and hydrolysed with trypsin, chymotrypsin and thermolysin. On the basis of the analyses of the resulting peptides, the complete amino acid sequence of RNAase U2 was determined, 2. When the sequence was compared with the amino acid sequence of RNAase T1 (EC 3.1.4.8), the following regions were found to be similar in the two enzymes; Tyr-Pro-His-Gln-Tyr (38-42) in RNAase U2 and Tyr-Pro-His-Lys-Tyr (38-42) in RNAase T1, Glu-Phe-Pro-Leu-Val (61-65) in RNAase U2 and Glu-Trp-Pro-Ile-Leu (58-62) in RNAase T1, Asp-Arg-Val-Ile-Tyr-Gln (83-88) in RNAase U2 and Asp-Arg-Val-Phe-Asn (76-81) in RNAase T1 and Val-Thr-His-Thr-Gly-Ala (98-103) in RNAase U2 and Ile-Thr-His-Thr-Gly-Ala (90-95) in RNAase T1. All of the amino acid residues, histidine-40, glutamate-58, arginine-77 and histidine-92, which were found to play a crucial role in the biological activity of RNAase T1, were included in the regions cited here. 3. Detailed evidence for the amino acid sequence of the sequence of the proteins has been deposited as Supplementary Publication SUP 50041 (33 PAGES) AT THE British Library (Lending Division)(formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1975), 145, 5.
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PMID:The amino acid sequence of ribonuclease U2 from Ustilago sphaerogena. 115 64

Interactions of several proteins with glutathione-insulin transhydrogenase (GIT) have been investigated by determining their ability to inhibit degradation of 125I-labeled insulin catalyzed by GIT. The inhibition by every insulin analog (des-Asn-des-Ala-pork insulin, desoctapeptide-pork insulin, des-Ala-pork insulin, pork insulin, proinsulin, and guinea pig insulin) was competitive vs. competitive vs. insulin indicating that they function as alternate substrates. The insulin analogs with the least hormonal activity showed the highest potency as inhigitors of insulin degradation. Whereas native ribonuclease and lysozyme showed little or no inhibition, their scrambled forms (i.e. reduced and randomly reoxidized) showed competitive inhibition with a potency greater than that of insulin. These results suggest that the conformation of the substrate or inhibitor is probably the major factor in determining the specificity for (or binding to) the enzyme. Studies withother peptide hormones showed competitive inhibition with vasopressin and oxytocin and noncompetitive inhibition with glycagon. The inhibition with growth hormone could be either competitive or noncompetitive. The inhibition by glucagon and growth hormone (physiologic antagonists of insulin) could serve as a control mechanism to modulate the activity of enzyme. The following showed very little or no inhibition; the native and scrambled form of pepsinogen, trypsin inhibitor of beef pancreas and of lima bean, C-peptide of pork proinsulin, and heptapeptide (B23-B29) of insulin.
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PMID:Interaction of insulin analogs, glucagon, growth hormone, vasopressin, oxytocin, and scrambled forms of ribonuclease and lysozyme with glytathione-insulin transhydrogenase (thiol: protein-disulfide oxidoreductase): dependence upon conformation. 117 Aug 77

Studies on the covalent structure of eland (Taurotragus oryx) pancreatic ribonuclease have been performed on tryptic and thermolysin digests. The first 45 residues have been determined with a Beckman sequencer. From the remaining part of the sequence only those peptides were sequenced that differed in amino acid composition with the corresponding peptide of bovine ribonuclease. Eland pancreatic ribonuclease differs in four positions from bovine pancreatic ribonuclease A, but more differences due to a different state of amidation may be present. The absence of an Asn-X-Thr/Ser sequence in the covalent structure of eland ribonuclease (asparagine 34 has been substituted by aspartic acid) explains the absence of a glycosidated component in eland ribonuclease.
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PMID:Studies on the covalent structure of eland pancreatic ribonuclease. 126 25

Pancreatic ribonuclease from muskrat (Ondatra zibethica) was isolated and its amino acid sequence was determined from tryptic digests of the performic acid-oxidized and the reduced and aminoethylated enzyme. The peptides have been positioned in the sequence by homology with other ribonucleases. This could be done unambiguously for all peptides except Arg-Arg (tentative position 32-33) and Ser-Arg (tentative position 75-76). The amino acid sequences of the peptides were determined by the dansyl-Edman method, with the exception of residues 23-25 and 99-102, which were positioned by homology. The enzyme differs in 38 positions from the enzyme from rat and in 31-42 positions from other mammalian pancreatic ribonucleases, while rat ribonuclease differs at 44-52 positions from the other enzymes. These data point to a common ancestry of the enzymes from muskrat and rat and an increased evolution rate of rat ribonuclease after divergence of the ancestors of both species. Muskrat ribonuclease contains no carbohydrate, although the enzyme possesses a recognition site for carbohydrate attachment in the sequence Asn-Val-Thr (62-64).
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PMID:The primary structure of muskrat pancreatic ribonuclease. 127 85

From the systematic replacements of amino acid residues of Escherichia coli ribonuclease HI with those of its thermophilic counterpart, the basic protrusion domain including region 6 (R6) from residues 91 to 95 was found to increase the structural stability of the mutant protein (Kimura, S., Nakamura, H., Hashimoto, T., Oobatake, M., and Kanaya, S. (1992) J. Biol. Chem. 267, 21535-21542). Further mutagenesis concentrating in the R6 region has revealed that replacements of Lys95 at the left-handed structure with Gly or Asn essentially enhances the protein stability. Gly and Asn substitutions stabilize the protein up to 1.9 kcal/mol and 0.9 kcal/mol in the free energy changes of unfolding, respectively. We propose that the amino acid substitution of left-handed non-Gly residue with Gly or Asn residue can be used as one of the general strategies to enhance protein stability, when such a non-Gly residue itself does not seriously contribute to protein stability.
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PMID:Thermostabilization of Escherichia coli ribonuclease HI by replacing left-handed helical Lys95 with Gly or Asn. 133 Oct 44


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