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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

M protein was extracted from type 24, group A streptococci with pepsin at pH 5.8 and was further purified by ammonium sulfate precipitation, ribonuclease digestion, ion-exchange chromatography, and isoelectric focusing. The purified pepsin extract of M (pep M) protein was shown to be free of nontype-specific immunoreactivity in (a) complement fixation tests with heterologous M antiserum, (b) skin tests in normal adult guinea pigs, and (c) passive hemagglutination tests for the presence of lipoteichoic acid sensitizing or antigenic activity. The pep M24 was highly immunogenic; two of three rabbits developed opsonic antibody titers of 1:256 and the third a titer of 1:32 6 wk after a single injection of 100-pg doses of pep M24 emulsified in complete Freund's adjuvant. The antisera lacked nontype-specific antibodies and produced single precipitin lines in agar gel diffusion tests against crude HC1 extracts of the homologous M protein. Thus, the type-specific antigenic determinant(s) of type 24 M protein appears to be separable from immunotoxic, cross-reactive antigens without loss of immunogenicity in rabbits. The mobility of pep M24 upon electrophoresis in 10 percent sodium dodecyl sulfate pelyacrylamide gel was consistent with an average mol wt of 33,500 daltons. Amino acid analysis demonstrated a predominance of alanine, followed by glutamic acid, lysine, leucine, and aspartic acid. Pep M24 contained an estimated six to seven methionine residues and approximately ten phenylalanine residues per molecule. No other aromatic amino acids were detected. Automatic Edman degradation of pep M24 yielded the sequence of the first 29 amino acids (the amino terminal amino acid being valine) of the amino terminal region of the molecule. The detection of only one new amino acid at each step of Edman degradation confirmed the homogeneity of the purified pep M24.
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PMID:Purification and properties of M protein extracted from group A streptococci with pepsin: covalent structure of the amino terminal region of type 24 M antigen. 32 68

The amino acid sequence of golden hamster pancreatic ribonuclease was determined by analysis of tryptic, chymotryptic, thermolytic, and CNBr peptides and by automatic sequence analysis of the intact protein. Like all RNases with an Asn-Met-Thr sequence at positions 34-36, hamster RNase is glycosylated at position 34 with a complex-type carbohydrated chain. Val-17, Ala-18, His-55, His-76 and Ala-90 have never been observed in other pancreatic RNases. Ala-90 replaces Ser-90, which had been invariant in all mammalian RNases studied so far. The amino acid sequence of hamster RNase differs at 15 positions from that of another Cricetidae rodent, the muskrat. The similarity between both ribonucleases was used to confirm a few less certain parts of the muskrat RNase sequence. The replacement rate of the RNases of the Cricetidae appeared to be higher than the average rate in the mammals, but much lower than the rate in another myomorph family, the Muridae (mouse and rat). Possibly, in many respects, the Cricetidae underwent less evolutionary change in recent times than the evolutionarily highly successful Muridae.
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PMID:The amino acid sequence of hamster pancreatic ribonuclease. 51 28

A description is given of the synthesis by fragment condensation of the peptide Gly-Glu-Ser-Arg-Glu-Ser-Ser-Ala-Asp-Lys-Phe-Lys-Arg-Gln-His-Met-Asp-Thr-Glu-Gly-Pro-Ser-Lys corresponding to the 1--23 amino acid sequence of rat pancreatic ribonuclease. This rat peptide combined with bovine S-protein yields a fully active ribonuclease S' analogue.
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PMID:Studies on polypeptides. XXVI. Synthesis of the N-terminal 1--23 peptide sequence of rat pancreatic ribonuclease; enzymatic activity of the hybrid complex with bovine S-protein. 64 56

Conformational changes induced in antibody molecules and in their Fab fragments by binding of antigen were investigated by the circular polarization of the fluorescence emitted by the tryptophan residues. This property of the fluorescence is related to the asymmetry, and thus to the conformation and environment, of the emitting chromophore. Changes in the circular polarization of the fluorescence of the antibody were observed upon binding of RNase to anti-RNase, of poly(DL-alanyl)-poly(L-lysine) to antipoly(D-alanine), and of the "loop" of lysozyme, a monovalent antigenic determinant, to anti"loop." The spectral changes were observed at different antigen-antibody ratios, including high antigen excess, indicating that they are due to antigen binding and not to aggregation. The circular polarization of fluorescence also detects changes in conformation of the different Fab fragments upon binding of the corresponding antigens. These changes in conformation were, however, markedly different from those observed for the whole antibody molecules, and indicated an interaction between the Fc and Fab fragments in the antibody molecule, and probably a change in the conformation of Fc upon binding of antigen to the antibody. In contrast, the small hapten, phosphorylcholine, did not induce a change in the circular polarization of the fluorescence of its antibody or corresponding Fab fragments. Reduction of the interchain disulfide bonds of the antibodies abolished the antigen-induced spectral changes due to the presence of the Fc portion in the molecule, but not the changes observed in Fab, suggesting that the disulfide bonds at the hinge region of the antibody are required for the transmission of the conformational change from the Fab to the Fc.
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PMID:Antigen-induced conformational changes in antibodies and their Fab fragments studied by circular polarization of fluorescence. 105 92

A 70-residue analog of RNase S-protein was synthesized by the solid phase method. It was obtained by omitting the NH2 terminus from positions 21 to 25 and the segments 36 to 40, 58 to 73, 87 to 96, and 113 to 114. Four residues were inserted to link the ends formed by the deletions. Half-cystine residues that had not been part of the deletions were replaced by alanine or leucine residues. The synthetic polypeptide was separated by gel filtration into a dimer and a monomer. Both fractions were purified further by ion exchange chromatography. The dimeric 70-residue S-protein analog had a specific activity of approximately 4% using RNA as substrate. It also cleaved other substrates of RNase A such as 5'-(3'-cytidylyl)-guanosine, 5'-(3'-uridylyl)-guanosine, and polycytidylic acid. The monomer of the 70-residue analog was less active but showed the same substrate specificity as the dimer. It was found that both fractions of the synthetic S-protein analog catalyzed only the transphosphorylation step of the RNase A mechanism and had very little if any activity in the hydrolysis step. Addition of natural S-peptide or S-protein did not increase the activity in the transphosphorylation reaction but greatly enhanced the reaction rate of the hydrolysis step. IN THE PRESENCE OF S-peptide, both monomeric and dimeric 70-residue S-protein, both monomeric and dimeric 70- residue S-protein analog had approximately 8% activity using cyclic cytidine 2':3'-monophosphate as substrate. The mixtures of monomer and dimer of the synthetic S-protein analog with natural S-protein generated even higher activities (151 and 74%, respectively) against this substrate despite the fact that the NH2-terminal portion of the natural enzyme (including His 12) was missing in both components of the two complexes. The 70-residue S-protein analog was completely inactive against DNA and (with one exception) against substrates for RNase T1. The close agreement of the substrate specificity of the synthetic analog with that of native RNase A in the transphosphorylation step suggested a remarkable conservation of the configuration of the active site despite drastic changes of the primary structure of the parent molecule. Possible implications of these results for the mechanism of action of RNase A are discussed.
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PMID:A synthetic 70-amino acid residue analog of ribonuclease S-protein with enzymic activity. 111 95

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

RNA identified by its base composition and T1 RNase oligonucleotide pattern as the message for silk fibroin was purified from mature posterior silk glands of Bombyx mori larvae and used to direct polypeptide synthesis in an Ehrlich ascites cell-free extract. Fibroin mRNA stimulated [3-H]alanine incorporation about 3- to 4-fold in the presence of 80 mM K+ and 4 mM Mg-2+. The stimulation was reduced in the presence of 5 times 10-minus 6 to 10-minus 4 M aurintricarboxylic acid, an inhibitor of the initiation of protein synthesis. The cell-free products were heterogeneous in size, including peptides as large as 100,000 daltons. They co-precipitated with carrier fibroin sequences after digestion with trypsin. A large fraction of the polypeptides synthesized in response to fibroin mRNA was precipitated by antiserum directed against amino acid sequences in noncrystalline region polypeptides of fibroin. Furthermore, after digestion with chymotrypsin, a major fraction of the cell-free products specifically co-precipitated with crystalline region sequences of native fibroin. The size and amino acid composition of the fibroin crystalline region polypeptides isolated from the cell-free products were similar to those from native fibroin.
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PMID:Translation of silk fibroin messenger RNA in an Ehrlich ascites cell-free extract. 117 Oct 97

Raney nickel (Ni(H)) catalyzes a specific reductive cleavage of carbon-sulfur bonds and, therefore, can be used to determine whether compounds are covalently bound to proteins through a sulfide linkage. When the covalent thymidylate synthetase-[3H]5-fluoro-2'-deoxyuridylic acid-[14C]-5,10-CH2H4-folate complex (Langenbach et al. (1972a), Biochem, Biophys. Res. Commun. 48, 1565) was denatured and then shaken with Ni(H) at 25 degrees C, both isotopes were rapidly cleaved from the protein, with identical reaction halftimes of less than 10 min. The liberated radioactivity was filterable through nitro-cellulose filters and comigrated with small molecules on Sephadex G-25. Both labels migrated identically upon paper chromatography. A [3H]5-fluoro-2'-deoxyuridylic acid-[35S]thymidylate synthetase complex was formed with enzyme isolated from Lactobacillus casei grown in the presence of [35S]cysteine. This complex, upon Ni(H) treatment, released both tritium and sulfur-35 at identical rates. Control experiments on amino acids showed that only the sulfur-containing amino acids are degraded by Ni(H). Cysteine was rapidly converted to alanine and methionine to alpha-aminobutyric acid. 5-Carboxymethylcysteine and 5-uracilylcysteine, simple models for the tenary enzyme-5-fluoro-2'-deoxyuridylic acid-5,10-CH2H4-folate complex, were converted to alanine at the same rate that 5-fluoro-2'-deoxyuridylic acid (FdUrd-5'-P) was cleaved from the enzyme. Native ribonuclease, which has a tightly coiled structure, was not affected by the reagent, but carboxymethylated ribonuclease was desulfurized. Amino acid analysis of Ni(H)-treated thymidylate synthetase showed that cysteine was the only amino acid degraded. Gel electrophoresis of the proteins after exposure to Ni(H) showed no breakage of polypeptide chains. These results support a sulfide linkage between FdUrd-5'-P and thymidylate synthetase in the covalent complex.
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PMID:The effect of Raney nickel on the covalent thymidylate synthetase-5-fluoro-2'-deoxyuridylate-5,10-methylenetetrahydrofolate complex. 125 51


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