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 complete amino acid sequence of mouse pancreatic ribonuclease has been determined by analysis of tryptic, chymotryptic, thermolytic and CNBr peptides and by automatic sequence analysis of the intact protein. The sequence of mouse RNase differs in 20--30% of the positions from other RNase sequences. Three unique or neraly unique substitutions were found, viz. Gly-68 leads to Arg-68, Arg-85 leads to His-85 and Ser-123 leads to Thr-123. All these three residues might be involved in interactions with substrate molecules. A most parsimonious tree of the myomorph rodent RNase shows that after the divergence of rat and mouse, the ribonuclease of rat accumulated substitutions at a rate 2.5--4.3 times as high as the rates in other branches of the tree and 23 times as high as the average rate in the Bovidae ribonuclease evolution. These extreme fluctuations in substitution rate are difficult to reconcile with the hypothesis of the evolutionary clock. The high evolution rate of rat ribonuclease is thought to be caused by positive selection, leading to new functional properties of the enzyme.
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PMID:The amino acid sequence of mouse pancreatic ribonuclease. Extremely rapid evolutionary rates of the myomorph rodent ribonucleases. 55 67

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

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

The size of the cavity around Ser68 of Escherichia coli ribonuclease HI was modulated by amino acid substitutions to examine the effects on the stability of the enzyme. Five mutant proteins, Ser68----Gly, Ser68----Ala, Ser68----Thr, Ser68----Val and Ser68----Leu, were constructed. Each of the mutant proteins exhibited at least 40% of the enzyme activity of the wild-type protein. The stabilities of the mutant proteins were determined from urea-denaturation and thermal-denaturation curves. Among the five mutations, only the Ser----Val mutation resulted in an increase in the stability of the enzyme. The melting temperature, tm, at pH 3.0 of the mutant protein Ser68----Val was increased by 1.9 degrees C. Its free-energy change of unfolding in the absence of urea, delta G(H2O), and the midpoint of the denaturation curve, [D]1/2, were also increased by 5.4 kJ/mol and 0.18 M, respectively. The increase in the stability of the enzyme is probably due to the filling of the cavity space around Ser68 by valine. However, the mutation of Ser68 to glycine or leucine residues resulted in a considerable decrease in stability. In these cases, some conformational changes occur, as suggested by the CD and 1H-NMR spectra of these mutant proteins.
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PMID:Effect of cavity-modulating mutations on the stability of Escherichia coli ribonuclease HI. 131 95

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

Seven hydrophobic residues ranging in size from glycine to phenylalanine have been substituted for the wild-type methionine residue at position 13 in a 15-residue truncated version (S15) of S-peptide, the small component of ribonuclease S. Complexes of both S-15 and the seven variants with S-protein yielded isomorphous crystals. The structures of all eight complexes have been refined to final R-factors in the range of 17-19%. [See Kim, E. E. Varadarajan, R., Wyckoff, H. W., and Richards, F. M. (1992) Biochemistry (preceding paper in this issue) for the description of the reference S-15 complex.] Multiple side-chain conformations were seen for six residues in all of the complexes and for two to three additional residues in at least some of the complexes. Three of the complexes, Gly, Ala, and alpha-amino-n-butyric acid (ANB), contained a single water molecule in the cavity near residue 13 that makes three hydrogen bonds to protein atoms. Although space is available, no evidence for additional water in this region, ordered or disordered, was found. The atoms in the cavity wall tend to shrink the cavity by moving in on the small residues and to swell the cavity by moving out for the larger Phe substitution. A swelling seen with leucine was attributed to a shape effect since Leu, Ile, and Met all have the same volume. A slight volume contraction of the collection of interior residues outside of the region of position 13 was also noted. (All changes noted are in the direction to maintain a constant packing density averaged over the whole protein.) Leu51, a surface hydrophobic residue, moved considerably in the G, A, and ANB complexes in directionswhich would tend to decrease the cavity volume. The only other major change in position, 1.5 A, was the 66-69 loop, which is about 25 A from position 13. His12, Phe120, and Asp121 appear to be involved in this movement, but the connection with position 13 is not clear at all. The thermodynamic data on the association reaction for all of these complexes have been previously reported [Connelly, P. R., Varadarajan, R., Sturtevant, J. M., & Richards, F. M. (1990) Biochemistry 29, 6108-6114; Varadarajan, R., Connelly, P. R., Sturtevant, J. M., & Richards, F. M. (1992) Biochemistry 31, 1421-1426]. Some comments are offered on our initial attempts to correlate the structural changes with the changes in the thermodynamic parameters.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Crystallographic structures of ribonuclease S variants with nonpolar substitution at position 13: packing and cavities. 146 20

We have isolated overlapping cDNA clones from human and hamster libraries which comprise the entire coding sequences for the prepro-alpha 1(V) collagen chains of both species. The translated polypeptide has a signal peptide of 36 amino acids, a central triple helical domain of 338 uninterrupted Gly-X-Y triplets, and 266 amino acids which comprise the C-telopeptide and propeptide. The N-propeptide and telopeptide are comprised of 522 residues in humans and 524 residues in hamsters. The cDNA-derived pro-alpha 1(V) amino acid sequences exhibit a variety of structural features characteristic of fibrillar collagens. Pro-alpha 1(V) is found to be unique among fibrillar collagen chains, however, in lacking potential cross-linking lysyl residues in either telopeptide, and in possessing potential N-asparaginyl-linked carbohydrate attachment sites in its N-propeptide. Of particular interest is the strong homology found between the pro-alpha 1(V) and pro-alpha 1(XI) collagen chains in most domains, with the notable exception of a subdomain in the globular region of the N-propeptide. RNase protection analysis of RNA with a variety of pro-alpha 1(V) cDNA-derived riboprobes indicates a broad distribution of expression of the pro-alpha 1(V) chain in tissues and suggests that transcripts encoding the pro-alpha 1(V) chain and the putative pro-alpha 1'(V) chain are not products of the same gene.
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PMID:The pro-alpha 1(V) collagen chain. Complete primary structure, distribution of expression, and comparison with the pro-alpha 1(XI) collagen chain. 172 13

Sequence analysis of cDNA clones encoding fibronectin (FN) from Xenopus laevis reveals extensive amino acid identities with other vertebrate FNs, including the presence of the Arg-Gly-Asp (RGD) cell attachment site in type III-10 and of a second, cell-binding site (EILDV) in the alternative spliced V region of the protein. These cDNAs have been used to study the expression of FN mRNAs during early development. Overall, levels of maternal FN mRNA remain constant until the mid- to late-gastrula stage when the accumulation of new FN transcripts is first apparent. RNase protection analyses reveal that the pattern of FN alternative splicing is similar to that reported for other species and does not change with the shift from maternal to zygotic mRNA expression. The cellular forms of the FN protein predominate in the early embryo with the EIIIA and EIIIB exons included in most mRNAs at this time. A comparison of V-region alternative splicing between embryonic and adult liver RNAs indicates a segment of 345 nucleotides that can be either completely excluded or included in mature FN transcripts but there is no evidence for additional V-region variants. Maternal mRNAs encoding alternatively spliced forms of FN can be specifically eliminated from Xenopus oocytes following the injection of antisense oligodeoxynucleotides into the cytoplasm, thereby making it possible to analyze the structure, composition, and function of FN mRNAs in early embryos.
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PMID:Identification and characterization of alternatively spliced fibronectin mRNAs expressed in early Xenopus embryos. 173 Mar 90

Ribonuclease T1 (RNase-T1) from Aspergillus Oryzae cleaves ribonucleic acid specifically at guanosine to yield oligonucleotides with terminal guanosine-3'-phosphate. It forms a complex with vanadate (association constant K approximately 145 +/- 30 M-1; delta (51V) = -514 ppm) with spectral features similar to the less stable complexes obtained with di- and tripeptides (Gly-His, Pros-His-Ala, Gly-His-Lys, Val-Glu) containing amino acids that are constituents at the active site of the enzyme. Guanosine also forms a (sparingly soluble) complex with vanadate. Its role is mimicked by inosine, which yields two soluble complexes with vanadate, characterized by delta values of -511 (K = 94 M-1) and -523 ppm (K = 305 M-1 in TRIS buffer and 685 m-1 in buffer-free solution). Comparison with literature values leads to an assignment of the delta = -523 signal to a complex where monovanadate, possibly in a trigonal bipyramidal geometry suggested for the transition state of the phosphate analogue, is coordinated to the 2'- and 3'-oxygens of the ribose ring. A drastic increase of complex stability is observed in the ternary vanadate (12-16 mM)/inosine(10.5 mM)/RNase-T1(5.4 mM) system. An approximate lower limit for the association constant is 1.5.10(5) M-2. The spectral characteristics of the main component of the binary vanadate/inosine complex are essentially maintained (delta = -525 ppm, half-width = 960 Hz), suggesting vanadate binding to the enzyme through hydrogen bonds.
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PMID:Binding of vanadate (V) to ribonuclease-T1 and inosine, investigated by 51V NMR spectroscopy. 251 77


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