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 acid denaturation of bovine pancreatic ribonuclease A in the presence of 0.2M sodium dihydrogen phosphate has been studied by n.m.r. spectroscopy. Phenylalanine, tyrosine and methionine resonances serve as monitors of the unfolding process. It is shown that the inhibitor shifts the equilibrium towards the native structure at acid pH. Exchange broadening of the C-2 resonances of the active site histidines, 12 and 119, occurs in the presence of phosphate, suggesting an equilibrium between native and unfolded structures. Stabilisation of the partially unfolded protein is observed at pH 1.5, as evidenced by the lack of the histidine resonance due to random coil protein. A scheme of the equilibria relating the various states of the protein is proposed.
...
PMID:Stabilisation of enzyme structures by inhibitors. A nuclear magnetic resonance study of the effect of phosphate on the acid unfolding of ribonuclease A. 1 21

1. The aromatic proton resonances in the 360-MHz 1H nuclear magnetic resonance (NMR) spectrum of bovine pancreatic ribonuclease were divided into histidine, tyrosine and phenylalanine resonances by means of pH titrations and double resonance experiments. 2. Photochemically induced dynamic nuclear polarization spectra showed that one histidine (His-119) and two tyrosines are accessibly to photo-excited flavin. This permitted the identification of the C-4 proton resonance of His-119. 3. The resonances of the ring protons of Tyr-25, Tyr-76 and Tyr-115 and the C-4 proton of His-12 were identified by comparison with subtilisin-modified and nitrated ribonucleases. Other resonances were assigned tentatively to Tyr-73, Tyr-92 and Phe-46. 4. On addition of active-site inhibitors, all phenylalanine resonances broadened or disappeared. The resonance that was most affected was assigned tentatively to Phe-120. 5. Four of the six tyrosines of bovine RNase, identified as Tyr-76, Tyr-115 and, tentatively, Tyr-73 and Tyr-92, are titratable above pH 9. The rings of Tyr-73 and Tyr-115 are rapidly rotating or flipping by 180 degrees about their C beta--C gamma bond and are accessible to flavin in photochemically induced dynamic nuclear polarization experiments. Tyr-25 is involved in a pH-dependent conformational transition, together with Asp-14 and His-48. A scheme for this transition is proposed. 6. Binding of active-site inhibitors to bovine RNase only influences the active site and its immediate surroundings. These conformational changes are probably not connected with the pH-dependent transition in the region of Asp-14, Tyr-25 and His-48. 7. In NMR spectra of RNase A at elevated temperatures, no local unfolding below the temperature of the thermal denaturation was observed. NMR spectra of thermally unfolded RNase A indicated that the deviations from a random coil are small and might be caused by interactions between neighbouring residues.
...
PMID:The aromatic residues of bovine pancreatic ribonuclease studied by 1H nuclear magnetic resonance. 3 52

Incubation of Neurospora crassa conidia with ribonuclease (RNase) A reduces transport of L-phenylalanine by those cells. Under similar conditions, oxidized RNase A, RNase T1, and RNase T2 do not have this effect. Incubation of conidia with active RNase covalently attached to polyacrylamide beads reduces L-phenylalanine transport. This indicates that the site of enzymatic action is at the cell surface. At the lower concentration of enzyme used in this study, incubation with RNase A reduces transport of L-phenylalanine by the general (G) amino acid permease. Increasing the enzyme concentration results in reduction of transport by the neutral aromatic (N)-specific permease. The increased transport activity that accompanies onset of conidial germination is also sensitive to incubation with RNase A. Application of the enzyme to actively transporting cells does not release amino acid transported prior to enzyme addition. Cells cultured on media supplemented with [2-14C] uridine release isotopic activity after RNase A incubation. Analogous treatments with Pronase, RNase T1, RNase T2, or deoxyribonuclease I do not release isotope activity. Pronase treatment does reduce L-phenylalanine transport. Incubation of conidia with RNase A also inhibits germination of those conidia.
...
PMID:Effects of ribonuclease A on amino acid transport in Neurospora crassa. 12 24

This paper demonstrates the existence of regions in eight small globular proteins in which the side chains of sulfur-containing amino acids (cysteine and methionine) alternate in space with side chains of aromatic amino acids (histidine, phenylalanine, tryptophan and tyrosine). The proteins are: rubredoxin, high potential iron protein, cytochrome c, flavodoxin, deoxyhemoglobin, trypsin inhibitor, ribonuclease-S, and lysozyme. The sulfur-pi-bonded 'chains' involve a minimum of five and a maximum of 10 amino acids, and contain the most polarizable atoms within proteins. S-pi-chains give extra stability to the folding of proteins; they may also afford paths for the step-wise movement of electrons.
...
PMID:Chains of alternating sulfur and pi-bonded atoms in eight small proteins. 20 19

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.
...
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 second derivative absorption spectra of serum albumin, insulin, ribonuclease and lysozyme were measured under various conditions to determine the state and amount of their phenylalanine residues. The second derivative spectra of these proteins were very similar to that of phenylalanine in the region between 245 and 270 nm where tryptophan and tyrosine residues caused no appreciable interference. Denaturation of proteins with urea or guanidine hydrochloride caused decrease in the intensity of the second derivative spectra, but scarcely affected the positions of peaks and troughs. The amounts of phenylalanine residues in proteins calculated from a second derivative spectra of denatured proteins coincided well with those reported in the literature. The states of the phenylalanine residues in the proteins could be deduced from the change in optical intensity on denaturation.
...
PMID:Estimation of state and amount of phenylalanine residues in proteins by second derivative spectrophotometry. 39 35

The characteristics of an in vitro polyuridylic acid dependent amino acid incorporating system prepared from germinating macroconidia of Microsporum canis are described. The incorporation of 14C-phenylalanine into polyphenylalanine is dependent on S-30 extract, adenosine triphosphate, magnesium ions and polyuridylic acid. Incorporation is slightly enhanced by yeast transfer ribonucleic acid and pyruvate kinase. The system is highly sensitive to ribonuclease, puromycin and miconazole (an antifungal agent), moderately sensitive to sodium fluoride and much less sensitive to phenethylalcohol, cycloheximide, chloramphenicol and deoxyribonuclease. Cell-free extract from ungerminated conidia has less capacity to synthesize the protein and during germination a marked increase in the protein synthetic activity is observed. The results from experiments wherein ribosomes and S-100 fraction from germinated and ungerminated spores are unterchanged, revealed that the defect in the extract from the ungerminated spore is in the ribosomes.
...
PMID:Studies on the macroconidia of Microsporum canis. Characteristics of in vitro amino acid incorporating system. 42

(1) The regulation of the accumulation of the isoflavonoid-derived phytoalexin phaseollin in cell suspension cultures of Dwarf French Bean (Phaseolus vulgaris/ has been investigated. (2) An elicitor preparation from cell walls of Colletotrichum lindemuthianum, the causal agent of anthracnose disease of French bean, caused a marked accumulation of phaseollin in the cultures. The elicitor induced phaseollin accumulation to a level of 60% that obtained with the artificial elicitor autoclaved ribonuclease A and was maximally active at a concentration (weight basis) of at least 50 times lower than required for maximal response to ribonuclease. (3) Elicitor preparations from cell walls of Phytophthora megasperma var. sojae, a fungal pathogen of soybean, and Botrytis cinerea, the common grey mould, were much less effective than the C. lindemuthianum wall-released elicitor. (4) There was a marked but transient increase in the extractable activity of phenylalanine ammonia-lyase, the enzyme catalysing the first reaction in the biosynthesis of phaseollin from L-phenylalanine, in response to the elicitor from C. lindemuthianum. (5) Comparative density labelling with 2H from 2H2O indicated that the elicitor stimulates de novo synthesis of phenylalanine ammonie findings provide the basis of a scheme for elicitor induction of phytoalexin accumulation.
...
PMID:Stimulation of de novo synthesis of L-phenylalanine ammonia-lyase in relation to phytoalexin accumulation in Colletotrichum lindemuthianum elicitor-treated cell suspension cultures of french bean (Phaseolus vulgaris). 47 49

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.
...
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

Prior investigation of the protein synthesizing properties of mitochondria involved the whole organelle. In order to better characterize these properties, the present study was concerned more specifically with the activity of the inner mitochondrial membranes (IMM) which recent investigation has implicated as the primary location of mitochondrial ribosomes. To further define mitochondrial protein synthesis simultaneous experimentation was also conducted utilizing cytoplasmic ribosomes thus enabling both qualitative and quantitative comparison between the two systems. Results from this series of investigations reveal a dramatic amino acid incorporating ability by the IMM fraction of the brain mitochondria. This activity, in turn, was shown to be highly independent of exogenous sources of ATP, GTP, pH 5 enzymes, and cytoplasmic ribosomes. Furthermore, the addition of an exogenous source of messenger RNA, polyuridylic acid or (poly (U)) which resulted in an increased incorporation of [14C]phenylalanine into polypeptide in the cytoplasmic system was found to have no effect on the IMM system. Upon comparison of the in vitro protein synthesizing properties of the IMM fraction with those of the cytoplasmic ribosomal system, it became evident that obvious differences existed in the degree of amino acid incorporation and in the sensitivity of this process to the various protein synthesizing inhibitors. Cytoplasmic ribosomes demonstrated a much greater [14C]leucine and [14C]phenylalanine incorporating activity than the IMM fraction. In addition, RNase and cyclohexamide had their greatest effect on the cytoplasmic system while the action of chloramphenicol was most potent on the IMM system. Although puromycin inhibited both protein synthesizing systems, this effect was greatest in the presence of cytoplasmic ribosomes.
...
PMID:In vitro protein synthesis by inner membranes of rat brain mitochondria. 73 21


1 2 3 4 5 6 7 8 9 10 Next >>

---