Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. o-Diphenol oxidase was isolated from potato tubers by a new approach that avoids the browning due to autoxidation. 2. There are at least three forms of the enzyme, of different molecular weights. The major form, of highest molecular weight, was separated from the others in good yield and with high specific activity by gel filtration through Bio-Gel P-300. 3. The major form is homogeneous by disc electrophoresis but regenerates small amounts of the species of lower molecular weight, as shown by rechromatography on Bio-Gel P-300. 4. There is an equal amount of RNA and protein by weight in the fully active enzyme. The RNA cannot be removed without loss of activity, and is not attacked by ribonuclease. 5. The pH optimum of the enzyme is at pH5.0 when assayed with 4-methylcatechol as substrate. It is ten times more active with this substrate than with chlorogenic acid or catechol. The enzyme is fully active in 4m-urea. 6. A minimal molecular weight of 36000 is indicated by copper content and amino acid analysis of the protein component of the enzyme. 7. The protein contains five half-cystinyl residues per 36000 daltons, a value similar to that found in o-diphenol oxidase from mushrooms. It also contains tyrosine residues although, when pure, it does not turn brown by autoxidation.
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PMID:The purification and properties of a ribonucleoenzyme, o-diphenol oxidase, from potatoes. 499 May 83

Four proteins, which have been designated A, B, C and D, have been purified from human parotid saliva. These proteins are the major constituents of parotid saliva which migrate rapidly to the anode in polyacrylamide electrophoresis at pH9.5. Gel filtration and polyacrylamide electrophoresis were employed in the purification procedures. After purification all four preparations were tested for homogeneity by electrophoresis at pH2.8 and 9.5, by isoelectric focusing in the pH range 3-10, by immunodiffusion, and by sedimentation in the analytical ultracentrifuge. None of the proteins showed significant activity in assays for amylase, acid and alkaline phosphatase, protease, lysozyme, ribonuclease, peroxidase, beta-glucuronidase, beta-galactosidase, iron-binding activity and esterase. No cross-reactions were detected with antisera specific for lactoferrin and 15 serum proteins. All four proteins were rich in glutamic acid, proline and glycine and were lacking completely the sulphur-containing amino acids. Proteins A and C contained no threonine or tyrosine. Carbohydrate could be demonstrated only in protein A at a concentration of 4% of the total protein.
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PMID:Purification and partial characterization of four proteins from human parotid saliva. 500 93

Temperature-jump studies have been used to detect a rapid reaction in the thermal unfolding of ribonuclease A (RNase A). The fast reaction occurs over a wide range of pH, and the results of a detailed study at pH 1.3 are reported here. Although its amplitude is small, the reaction is easily measurable over the entire temperature range of thermal unfolding. It occurs in the millisecond time range, and is faster by 3-4 orders of magnitude than the slow unfolding reaction studied previously. Unfolding is measured here by the change in absorbance at 287 nm, which reflects the exposure to solvent of buried tyrosine groups. Since the fast reaction has a detectable amplitude only in the temperature range of unfolding, it apparently detects the presence of intermediate, partly-folded states. Previous equilibrium studies of the unfolding of RNase A in the pH range 1-2 have indicated that it is essentially a 2-state reaction, without detectable intermediates. The existence of a rapid transient phase in the unfolding of RNase A had been predicted previously from a model for this unfolding reaction, based on nucleation-dependent sequential folding. The model served to reconcile kinetic and equilibrium studies of the thermal unfolding reaction of RNase A at neutral pH. Kinetic studies had shown that the slow unfolding reaction, measured at 287 nm, could be represented as a single exponential process, as expected for a 2-state reaction. However, earlier equilibrium measurements, especially the calorimetric studies of Sturtevant and coworkers, had revealed significant deviations from the 2-state behavior at neutral pH. These conflicting observations are explained by the model, which satisfies closely many criteria for a 2-state unfolding, even when appreciable concentrations of partly folded molecules are present. In particular, it predicts that the final, and major, portion of the kinetic reaction will occur as a single process characterized by an exponential time course.
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PMID:The sequential unfolding of ribonuclease A: detection of a fast initial phase in the kinetics of unfolding. 528 48

The RNA extracted from normal peritoneal macrophages exposed to a linear, random synthetic polypeptide, Glu(60)Ala(30)Tyr(10), initiated an immune response in C57B1/6J mice, although this strain responds very poorly to the antigen itself. From 10 to 150 micrograms of RNA obtained from mouse, rat, or rabbit macrophages was injected intraperitoneally into recipient mice, and specific antibody was detectable by passive hemagglutination 3 to 4 weeks later. Treatment of the RNA with ribonuclease destroyed its ability to initiate a specific immune response. The RNA contained by weight 0.02 percent of the (specific) antigen. The RNA obtained from cells incubated with a second polypeptide, Glu(36)Lys(24)Ala(40), initiated a response specific for this polymer. This RNA even when incubated in vitro with Glu(60)Ala(30)Tyr(10) failed to initiate antibody formation specific for Glu(60)Ala(30)Tyr(10).
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PMID:Antibody formation: initiation in "nonresponder" mice by macrophage synthetic polypeptide RNA. 564 72

The quantum yields for the disruption of various amino acids in glutathione and ribonuclease by 229, 254, 265, and 280 nm UV photons have been determined. The results of the measurements on the destruction of tyrosine and histidine and the loss of enzymic function in RNAse and the disruption of cystine in both compounds lead to the following conclusions: (a) The photodestruction of some and perhaps many constituent amino acid residues does not cause RNAse inactivation. (b) Contrary to the basic premise of proposals made by other authors, the photochemical yields of constituent residues in a protein are not the same as that for the same amino acids in solution alone-the difference is a function of the exciting wavelength. Further, the extent of histidine destruction varies by a large factor among three proteins. (c) Consistent with previous predictions, the present results show that photons absorbed in the aromatic residues of RNAse cause the disruption of cystines elsewhere in the enzyme. (d) Although cystine disruption appears to be the most prevalent mode of RNAse inactivation by photons of the four wavelengths studied, some of the minor mechanisms leading to loss of enzymic function may vary with the UV energy.
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PMID:Photochemical yields in ribonuclease and oxidized glutathione irradiated at different wavelengths in the ultraviolet. 569 11

1. Bovine pancreatic ribonuclease is not reduced by GSH at near-physiological concentrations and pH. 2. Disruption of the structure of ribonuclease by proteolytic enzymes leads to products that can be reduced by GSH. 3. At higher temperatures the disulphide bonds of ribonuclease are completely reduced by GSH in a coupled system. The T(tr) is 51 degrees and this has been found to be lower than the T(tr) for the abnormal tyrosine residues under the same conditions.
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PMID:The reactivity of the disulphide bonds of bovine pancreatic ribonuclease with glutathione. 586 27

We make use of the known exchange rates of individual amide proton in the S-peptide moiety of ribonuclease S (RNAase S) to determine when during folding the alpha-helix formed by residues 3 to 13 becomes stable. The method is based on pulse-labeling with [3H]H2O during the folding followed by an exchange-out step after folding that removes 3H from all amide protons of the S-peptide except from residues 7 to 14, after which S-peptide is separated rapidly from S-protein by high performance liquid chromatography. The slow-folding species of unfolded RNAase S are studied. Folding takes place in strongly native conditions (pH 6.0, 10 degrees C). The seven H-bonded amide protons of the 3-13 helix become stable to exchange at a late stage in folding at the same time as the tertiary structure of RNAase S is formed, as monitored by tyrosine absorbance. At this stage in folding, the isomerization reaction that creates the major slow-folding species has not yet been reversed. Our result for the 3-13 helix is consistent with the finding of Labhardt (1984), who has studied the kinetics of folding of RNAase S at 32 degrees C by fast circular dichroism. He finds the dichroic change expected for formation of the 3-13 helix occurring when the tertiary structure is formed. Protected amide protons are found in the S-protein moiety earlier in folding. Formation or stabilization of this folding intermediate depends upon S-peptide: the intermediate is not observed when S-protein folds alone, and folding of S-protein is twice as slow in the absence of S-peptide. Although S-peptide combines with S-protein early in folding and is needed to stabilize an S-protein folding intermediate, the S-peptide helix does not itself become stable until the tertiary structure of RNAase S is formed.
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PMID:Amide proton exchange used to monitor the formation of a stable alpha-helix by residues 3 to 13 during folding of ribonuclease S. 609 89

Rat brain extracts contain two heat-stable, nondialyzable inhibitors of tubulinyl-tyrosine carboxypeptidase. One of the inhibitors was sensitive to ribonuclease and insensitive to trypsin and pronase, indicating that the inhibitor is RNA. This is supported by the observation that purified RNA from rat brain inhibited the enzyme activity to the same extent as similar amounts of the endogenous RNA. Similar results were obtained with calf liver RNA. The other inhibitor was purified by chromatography on a DEAE-Sephadex and identified as proteoglycan. The elimination of the protein moiety of the proteoglycan resulted in a small increase of its inhibitory activity. Glycosaminoglycan was released from the proteoglycan by beta elimination, indicating that the linkage between glycosaminoglycan and the protein moiety is through an O-glycosidic bond. The glycosaminoglycan contains uronic acid, hexosamine and sulfate in a molar ratio of 1:1.01:0.99, respectively. Treatment of the glycosaminoglycan with chondroitinase ABC completely abolished its inhibitory activity. Chondroitin sulfate A, chondroitin sulfate B, chondroitin sulfate C, and the brain glycosaminoglycan inhibited tubulinyl-tyrosine carboxypeptidase to the same extent when used in comparable amounts.
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PMID:Inhibition of tubulinyl-tyrosine carboxypeptidase by brain soluble RNA and proteoglycan. 616 Nov 29

Using a rapid phenol extraction assay, an enzyme was purified from uninfected HeLa cells that can cleave the 5'-terminal protein (VPg) from poliovirus RNA. Both cytoplasmic and nuclear extracts had enzymes with similar behavior. A polypeptide of molecular weight 27,000 was the major one present in the purified preparation. Assuming that this protein is the enzyme, a very low turnover number was calculated for it. The purified enzyme would cleave the tyrosine-phosphate bond linking VPg to poliovirus RNA with minimal degradation of the RNA or of VPg. If the RNA was first treated with proteinase K to degrade VPg, leaving a small peptide on the RNA, this peptide could also be removed by the enzyme. If the RNA was degraded with T1 RNase, leaving VPg attached to a nonanucleotide, the enzyme still would cleave off VPg, although incompletely. If the RNA was degraded completely, leaving either pUp or pU attached to VPg, the enzyme would not remove the nucleotides from the protein. Thus, for the enzyme to be active requires some length of polynucleotide attached to the protein but only a short peptide need be present for the enzyme to act.
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PMID:Purification and properties of a HeLa cell enzyme able to remove the 5'-terminal protein from poliovirus RNA. 624 32

3-N-Carboxymethyl-His-12 and 1-N-carboxymethyl-His-119-RNase A bind to the naturally occurring RNase inhibitor, isolated from human placenta, 1.3 and 3.6 times, respectively, more strongly than does native RNase A. Near-ultraviolet circular dichroism measurements indicate that the conformational change which occurs upon carboxymethylation of either of the active site histidine residues appears different from that which the protein undergoes upon binding of substrate of a substrate analogue. Specific carboxymethylation of Lys-41 of RNase A decreased the strength of the interaction between the enzyme and the RNase inhibitor to about 12% of the initial value. The near-UV CD spectra of Cm-Lys-41-RNase A and of acetimidyl-RNase A (9.3 lysines modified) and carbamylated RNase A (3.0 lysines modified), which also have weaker interactions with RNase inhibitor of 25% and 10%, respectively, show a negative [theta]MRW identical to that of native RNase A at 275 nm but are altered in the positive [theta]MRW at 240 nm. The CD measurements suggest that one or more tyrosine residues of RNase A may be involved in the interaction with inhibitor. The effects of pH and salt concentration suggest that a major part of the protein-protein interaction is probably through nonpolar forces. The strengths of interactions between the inhibitor and pancreatic RNases from several species were very similar. Since Tyr-92 is the only tyrosine residue retained in all of the species studied, this residue may have a key role in the nonpolar interaction. The data presented herein suggest that the interaction between RNase A and the inhibitor involves the positively charged epsilon-NH2 group of Lys-41 of RNase A. This interaction could result in the inactivation of the enzyme.
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PMID:The role of lysine-41 of ribonuclease A in the interaction with RNase inhibitor from human placenta. 625 94


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