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)

The histidine C-2 proton NMR titration curves of ribonuclease S-peptide (residues 1 to 20) and S-protein (residues 21 to 124) are reported. Although S-protein contains 3 histidine residues, four discrete resonances are observed to titrate. One of these arises from the equivalent histidine residues of unfolded S-protein. The variation in area of the four resonances indicate that there is a reversible pH-dependent equilibrium between the folded and unfolded forms of S-protein, with some unfolded material being present at most pH values. Two of the resonances of the folded S-protein can be assigned to 2 of the histidine residues, 48 and 105, from the close similarity of their titration curves to those in ribonuclease. These similarities indicate a homology of portions of the folded conformation of S-protein to that of ribonuclease in solution. These results indicate that the complete amino acid sequence is not required to produce a folded conformation similar to the native globular protein, and they appear to eliminate the possibility that proteins fold from their NH2 terminus during protein synthesis. The low pH inflection present in the titration curve assigned to histidine residue 48 in ribonuclease is absent from this curve in S-protein. This is consistent with our previous conclusion that this inflection arises from the interaction of histidine 48 with aspartic acid residue 14, which is also absent in S-protein. The third titrating resonance of native S-protein is assigned to the remaining histidine residue at position 119. The properties of this resonance are not identical with either of the titration curves of the active site histidine residues 12 and 119 of ribonuclease. The resonance assigned to histidine 119 is the only one significantly affected on the addition of sodium phosphate to S-protein, indicating that some degree of phosphate binding occurs. In both the absence and presence of phosphate this curve also lacks the low pH inflection observed in the histidine 119 NMR titration curve in ribonuclease. This difference presumably arise from a conformational between ribonuclease and the folded S-protein involving a carboxyl group.
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PMID:Nuclear magnetic resonance titration curves of histidine ring protons. Ribonuclease S-peptide and S-proteins. 0 55

Optimal conditions were established for RNase activity measurement. The enzyme was measured in human seminal plasma as well as in spermatozoa. Results suggest that sperm enzyme may come from seminal plasma contamination and that RNase may be used as a marker enzyme for seminal plasma contamination. Sodium dodecylsulfate, a reagent utilized to produce the solubilization of the spermatozoa, produced a very strong inhibition of the RNase at low concentrations (530 muM). Zinc sulfate and EDTA also produced inhibition of the RNase activity. Such inhibition may be very useful in future studies of RNA metabolism in human spermatozoa.
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PMID:Human semen ribonuclease. Location, properties and inhibition by sodium dodecyl sulfate, zinc sulfate and EDTA. 0 82

In the hepatic cytosol fraction of bullfrog, Rana catesbeiana, an alkaline RNase [EC 3.1.4.22] exists in two forms. One is the free form of RNase, which elutes from a carboxymethyl-cellulose column at a concentration of 0.2 M NaC1. The other is a masked or latent form (RNase-RNase inhibitor complex) which is not adsorbed on the carboxymethyl-cellulose column and which can be converted to the free form of RNase by the addition of p-chloromercuribenzoate. Electrophoretically pure RNase was obtained by the following procedure. The unadsorbed fraction of hepatic cytosol on a column of carboxymethyl-cellulose was treated with p-chloromercuribenzoate and then applied to a second carboxymethyl-cellulose column. The molar weight of RNase was determined to be approximately 12,000 by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. From the results of gel filtration, the molecular weight of the RNase-RNase inhibitor complex was 130,000. The RNase hydrolyzed poly C, poly U, and poly I, but not poly A or poly G. When poly C was used as a substrate, 2',3'-cyclic CMP as an intermediate and 3'-CMP as a final product were identified. The results of amino acid analysis indicated the presence of an unusual component. The general properties of the RNase and the RNase-RNase inhibitor complex are also reported.
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PMID:Purification and properties of an alkaline ribonuclease from the hepatic cytosol fraction of bullfrog, Rana catesbeiana. 0 78

Four urinary alkaline ribonucleases (RNase, EC 3.1.4.22) were purified from patients with nephrotic syndrome using phosphocellulose, DEAE-cellulose and Sephadex G-75 chromatographiy. These enzymes were designated as RNases 1--4, respectively, in order of elution on phosphocellulose chromatography. The respective purification of each fraction was 41-, 23-, 34- and 27-fold with a total recovery of 25%. The pH optima of these RNases were around 8.5 with Tris/HCl buffer and the reaction was activated by mono- and divalent cations, such as Na+, K+, Mg2+ and Ca2+, but inhibited by Fe2+, Cu2+ and Zn2+. EDTA had little effect on the velocity of reaction. The molecular weights of RNases 1--4 were estimated by gel filtration as 45 000, 32 000, 20 000, and 13 000, respectively. Each enzyme hydrolyzed pyrimidine nucleotides preferentially with higher affinity for poly(C) than poly (U) as determined with synthetic polymers and was free from other nucleolytic enzymes. The patients with renal disorders excreted one to four RNases in urine and the number of enzymes increased as the concentration of urinary protein increased. On the other hand, normal subjects excreted a single fraction essentially identical to RNase 1.
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PMID:Purification and properties of urinary alkaline ribonucleases from patients with nephrotic syndrome. 1 98

Radioactive selenite reacts with purified human and goat immunoglobulins at acidic and neutral pH. The antigenic properties of the immunoglobulins are retained during the selenium labelling as shown by immunoelectrophoresis and autoradiography. Pepsin digests of 75Se-labelled IgG possess 75Se both in the (Fab')2 fraction and in the low molecular weight peptides derived from the Fc domains. Alpha-1-acid glycoprotein, ribonuclease, and lysozyme are also labelled by this procedure. Enhancement of 75Se incorporation by urea, guanidinium chloride, mercaptoethanol, sodium sulfite and carrier selenite is interpreted as an effect of destabilization of IgG disulfide bonds. Up to 1.4 g atoms Se per mol IgG have been incorporated. We assume that selenite is cleaving disulfides by a process akin to sulfitolysis. The lability of the isolated 75Se-labelled IgG to high concentrations of mercaptans and sulfite is consistent with this idea. These 75Se-labelled proteins may be useful in structure studies and radioimmunoassay.
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PMID:Reaction of selenium with immunoglobulin molecules. 1 84

Acid ribonuclease, free of nucleases and phosphatases, is isolated from rat thymus chromatin. The pH optimum of the enzyme is 5.0-5.5, optimal concentrations of Na+ and K+ ions are 0.05-0.15 M and 0.05 M respectively, Mg2+ inhibits the enzyme activity. The enzyme hydrolyses poly U, poly AU, cytoplasmic and nuclear RNAs, but does not attack poly A, polyG, polyC, poly A:poly U, native and denatured DNA'S. The enzyme is 3'-endonuclease, it splits the bond between the 5'-carbon atom of adenosine, guanosine and uridine and 3'-phosphate of uridilic residue. Middle length of oligonucleotides after the hydrolysis of cytoplasmic RNA comprises 10 nucleotides. Possible role of the enzyme in the processing of nuclear RNAs is discussed.
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PMID:[Characteristics of acid ribonuclease from rat thymus chromatin]. 1 99

Donor deoxyribonucleic acid (DNA) single strands exist in a complex during the eclipse phase in pneumococcal transformation. This eclipse complex exhibited specific physical properties distinct from those of both pure DNA single strands and native DNA. These included a lower affinity for diethylaminoethyl-cellulose and hydroxylapatite than that of single-strand DNA, faster sedimentation than the DNA chains that it contains, and a buoyant density in Cs2SO4 lower than that of native DNA. The complex was dissociated by treatments with sodium dodecyl sulfate, NaOH, guanidine-hydrochloride, chloroform, and proteinase K but was insensitive to ribonuclease.
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PMID:Transformation in pneumococcus: existence and properties of a complex involving donor deoxyribonucleate single strands in eclipse. 2 Nov 66

Sodium acetate and sulphuric acid extracts of human epidermis can each be separated by chromatographic techniques into three or more fractions with ribonuclease activity. Eight of these fractions were compared with respect to molecular weight, pH activity profile, polyribonucleotide hydrolysis, and activity in the presence of low levels of spermidine. Sodium acetate and sulphuric acid extracts were also prepared from callus and from psoriatic lesions and compared with extracts from normal epidermis for their response to exogenous spermidine. All eight human epidermal ribonuclease fractions studied had an apparent molecular weight of 15,000 daltons. Seven of the ribonuclease fractions were optimally active at alkaline pHs (pH 7.3-7.6 in sodium phosphate and pH 8.I in Tris-HCl) while the eighth ribonuclease was most active at pH 5.6 in a citrate-phosphate buffer. All enzymes hydrolyzed polycytidylic acid and five also hydrolyzed polyuridylic acid. None hydrolyzed polyadenylic acid. Seven of the eight ribonucleases studied exhibited greater activity in the presence of added spermidine. The extracts from psoriatic scales showed markedly elevated ribonuclease levels which could not be raised further by the addition of spermidine.
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PMID:Epidermal nucleases. III. The ribonucleases of human epidermis. 2 41

1. Double-stranded f2 sus11 or Qbeta RNAs, resistant to bovine pancreatic RNAase A in 0.15 M NaCl/0.015 M sodium citrate (SSC), are quickly and completely degraded at 10-fold lower ionic strength (0.1 X SSC) under otherwise similar conditions. At this ionic strength the secondary structure of double-stranded RNA is maintained, as judged by the following: (a) the unchanged resistance of double-stranded RNA and DNA, under similar low ionic strength conditions, to nuclease S1 from Aspergillus oryzae, in contrast with the sensitivity of the corresponding denatured nucleic acids to this enzyme, specific for single-stranded RNA and DNA; (b) the co-operative pattern of the thermal-transition profile of double-stranded RNA (with a Tm of 89 degrees C) in 0.1 X SSC. 2. Whereas in SSC bovine seminal RNAase (RNAase BS-1) and whale pancreatic RNAase show an activity on double-stranded RNA significantly higher than that of RNAase A, in 0.1 X SSC the activity of the latter enzyme on this substrate becomes distinctly higher than that of RNAase BS-1, and similar to that of whale RNAase. 3. From these results it is deduced that the secondary structure is probably not the only nor the most important variable in determining the susceptibility double-stranded RNA to ribonuclease. Other factors, such as the effect of ionic strength on the enzyme and/or the binding of enzyme to nucleic acids, may play an important role in the process of double-stranded RNA degradation by ribonucleases specific for single-stranded RNA.
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PMID:How much is secondary structure responsible for resistance of double-stranded RNA to pancreatic ribonuclease A? 2 5

Acid RNase was purified from normal human serum about 2400-fold by chromatography on phosphocellulose and Sephadex G-75 and rechromatography on Sephadex G-75. Assayed with yeast RNA as substrate, the enzyme showed the maximal activity at about pH 6.5 with sodium phosphate buffer. The reaction was activated by Na+, K+, and spermine, but it was not affected greatly by Mg2+, Co2+, and EDTA. Ca2+, Fe2+, Zn2+, and Cu2+ inhibited the reaction. Among the synthetic substrates examined, the enzyme preferentially hydrolyzed pyrimidine nucleotides, with a higher affinity for polycytidylate than for polyuridylate. The enzyme was thermolabile, but it stabilized with bovine plasma albumin. The molecular weight was approximately 15,000, estimated gel filtration on Sephadex G-75, and its isoelectric pH was above 11.0. From normal human leukocytes, acid RNase was purified about 400-fold by the same procedure described previously except that rechromatography on Sephadex G-75 was omitted. The properties of leukocytic RNase were found to be similar to those of serum acid RNase, but the latter enzyme differed in substrate specificity substantially from leukocytic RNase, preferring polyuridylate to polycytidylate. This evidence shows that serum RNase is not of leukocytic origin under normal physiological conditions.
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PMID:Purification and properties of acid ribonucleases in human serum and leukocytes. 2 64


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