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 study of the temperature dependence of the hydrolysis of cytidine 2',3'-phosphate by bovine pancreatic ribonuclease A (EC 3.1.27.5) at pH 7.0 by using the pH-stat method showed a transition at 4 degrees C [J. A. Biosca and C. M. Cuchillo (1980) Biochem. J. 189, 655-657]. The breaks found in the Van't Hoff and Arrhenius plots at pH 7.0 were confirmed in the present work by following the reaction spectrophotometrically with a stopped-flow spectrophotometer adapted to the use of sub-zero temperatures. Similar results were found at pH 5.5. In addition it was found that the discontinuity disappears when 40% ethyleneglycol is present in the reaction mixture. However, in this latter instance a discontinuity around 0 degrees C appears in the Arrhenius plot. To explore the possibility that all these effects were due to a conformational transition in the protein, thermal perturbation experiments were carried out with the enzyme. A change in the slope of the plot of delta A290 as a function of temperature was found around 6 degrees C at pH 7.0 but not at pH 5.5. The results reported here can be interpreted as due to a change in the protein structure induced by the change of the structure of water. The studies carried out in the presence of ethyleneglycol also open the way to the cryoenzymological experimentation on ribonuclease.
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PMID:Influence of the structure of water on the hydrolysis of cytidine 2',3'-phosphate catalysed by bovine pancreatic ribonuclease A. 628 86

The preparation, properties, and immunogenicity of the dialyzable factor from a ribosomal fraction of Salmonella typhimurium are described. The ribosomal fraction was purified to eliminate O-antigenic components, by affinity chromatography (Sepharose-anti-O antibody conjugates used as immunoadsorbent). The dialyzable factor was obtained in the concentrated dialysate of the purified ribosomal fraction which was alternately frozen in dry-ice acetone and thawed in an 80 C water bath, for a total of five or six cycles. When this preparation was tested for its ability to protect mice against challenge with 1,000 LD50 of the homologous bacteria, it afforded 100% protection at a dose equivalent to 5.0 micrograms of RNA. The protection conferred by this factor was mainly cell mediated but immune serum enhanced this immunity despite the fact that no antibodies were detected in it. The protective activity of this factor was sensitive to RNase digestion but resistant to proteolytic enzymes. Ion exchange chromatography of this factor with DEAE-Sephadex A-25 (in 7 M Urea-0.02 M Tris-HCl buffer, pH 7.5) resulted in a single A260 peak which was found to be immunogenic. Chemical analysis of this peak after it was concentrated and desalted revealed that this immunogenic fraction was composed mainly of mixed nucleotides. The data indicate that protective immunity conferred by a ribosomal vaccine is associated with RNA but may not require the intact RNA molecule.
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PMID:Immunogenic dialyzable factor derived from a ribosomal fraction of Salmonella typhimurium. I. Preparation of the protective dialyzable factor from the ribosomal fraction by the freeze-thaw procedure. 634 23

Bacteria were isolated from lake water, and their ability to remain viable in a dilute, nutrient-deficient environment was tested by a method that permits suspension of test bacteria between two appressed microporous membranes in an aqueous environment. This approach permitted separation of the lake isolates into two categories. Members of the tribe Klebsielleae were shown to have a prolonged survival rate of 40% or better after 24 h, whereas nonsurvivors were not viable for much longer than 24 h. These nonsurvivors belonged to the genera Acinetobacter, Aeromonas, Alcaligenes, Erwinia, Escherichia, Flavobacterium, and Pseudomonas. Differences in ribonuclease and adenosine triphosphatase levels between Escherichia coli (nonsurvivor) and Klebsiella (survivor) cells were detected. At pH 7.5, stressed E. coli cells contained 14% of the adenosine triphosphatase activity detected in the control, whereas at pH 5.5, in the presence of calcium ions, these same cells contained 50% of the control adenosine triphosphatase levels. At pH 7.2, E. coli cells were strongly inhibited by an adenosine triphosphatase inhibitor, bathophenanthroline (88%); oligomycin (64%); and the proton ionophore carbonyl- cyanide-m-chlorophenyl hydrazone (67%). Both sodium azide and valinomycin were only moderately inhibitory (15 and 28%, respectively). Although the ability to scavenge internal endogenous reserves seems important, we postulate that certain enteric bacteria are capable of utilizing acidic conditions (pH 5.5) as an electrochemical gradient to generate necessary high-energy intermediates for prolongation of survival beyond that possible in environments of near-neutraL pH.
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PMID:Bacterial survival in a dilute environment. 645 90

The bichromatic paper disk spectrophotometry ultramicromethod developed in the "Stefan S. Nicolau" Institute of Virology can be successfully applied to the study of viral and cellular nucleic acids. The main applications - succinctly presented in the review - refer to : the identification and spectral characterization of nucleic acids, their quantitative determination, the study of the helix - statistical coil transition, the evaluation of the degree of polymerization of single stranded polynucleotides, the study of the kinetics of chemical and enzymatic hydrolysis and the determination of RNase activity, e.g. in human serum, the demonstration of the interaction between nucleic acids and other molecules of biological interest (biopolymers, poly- and oligocations, etc.), the rapid characterization of the ion exchange capacity of chromatography papers and of a mobile phase of the water - alcohol - electrolyte type.
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PMID:Characterization of nucleic acids by bichromatic paper disk spectrophotometry. 651 12

In order to investigate the role of carboxyl groups of a base non-specific ribonuclease from Aspergillus saitoi [EC 3.1.27.1] (RNase M, molecular weight 36,000), the modification of RNase M with a water-soluble carbodiimide, 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide(CMC), was studied. The inactivation of RNase M proceeded almost linearly with the incorporation of about 9.5 CMC moieties. The peptide backbone structure of the modified RNase M was practically the same as that of the native RNase M, as assessed from the CD spectra in the region of 200-250 nm. In the presence of competitive inhibitors, adenosine, and cytidine, inactivation of RNase M by CMC was partially inhibited. In the presence of cytidine (1 M), the modification of about 4 carboxyl groups of RNase M proceeded with a slight loss of enzymatic activity (ca. 20%). Further modification inactivated RNase M with the incorporation of ca. 4-5 CMC without any detectable intramolecular peptide bond formation. Therefore, it was concluded that carboxyl groups responsible for enzymatic activity were included among these carboxyl groups protected by cytidine. The logarithm of the half-live of the inactivation of RNase M by CMC was a linear function of log[CMC] with a slope of minus one, indicating that at least one carboxyl group among the modified ones may be essential for catalysis. The digestion of CMC-modified RNase M with carboxypeptidase A eliminated the carboxyl terminal group from the site of CMC modification.
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PMID:Modification of a major ribonuclease from Aspergillus saitoi with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide. 657 11

The antitumor activity of a marine bacterium, Vibrio anguillarum, against Ehrlich carcinoma cells in ddY mice was investigated. The aqueous layer obtained by the hot phenol-water procedure exhibited more antitumor activity than did the middle layer or the phenol layer. This finding indicates that lipopolysaccharide (LPS) derived from V. anguillarum exhibits significant antitumor activity. In fact, mice injected with LPS obtained by ultracentrifugation and treatment with RNase had a longer mean survival period than the control mice. V. anguillarum LPS also inhibited the growth of syngeneic fibrosarcoma induced by 3-methylcholanthrene in C57BL/6 mice. V. anguillarum LPS possesses no 2-keto-3-deoxyoctonate, a regular sugar component of the core region of most gram-negative bacterial LPS, suggesting that 2-keto-3-deoxyoctonate is unnecessary for the antitumor activity of LPS.
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PMID:Antitumor activity of 2-keto-3-deoxyoctonate-free lipopolysaccharide of Vibrio anguillarum in mice. 686 49

Camphorquinone-10-sulfonic acid hydrate was prepared by the action of selenous acid on camphor-10-sulfonic acid. Camphorquinone-10-sulfonylnorleucine was prepared either from the sulfonic acid via the sulfonyl chloride or by selenous acid oxidation of camphor-10-sulfonylnorleucine. These reagents are useful for specific, reversible modification of the guanidino groups of arginine residues. Camphorquinonesulfonic acid is a crystalline water-soluble reagent that is especially suitable for use with small arginine-containing molecules, because the sulfonic acid group of the reagent is a convenient handle for analytical and preparative separation of products. Camphorquinonesulfonylnorleucine is more useful for work with large polypeptides and proteins, because hydrolysates of modified proteins may be analyzed for norleucine to determine the extent of arginine modification. The adducts of the camphorquinone derivatives with the guanidino group are stable to 0.5 M hydroxylamine solutions at pH 7, the recommended conditions for cleavage of the corresponding cyclohexanedione adducts. At pH 8-9 the adducts of the camphorquinone derivatives with the guanidino group are cleaved by o-phenylenediamine. The modification and regeneration of arginine, of the dipeptide arginylaspartic acid, of ribonuclease S-peptide, and of soybean trypsin inhibitor are presented as demonstrations of the use of the reagents. The use of camphorquinonesulfonyl chloride to prepare polymers containing arginine-specific ligands is discussed.
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PMID:Camphorquinone-10-sulfonic acid and derivatives: convenient reagents for reversible modification of arginine residues. 692 87

Thermal denaturation of ribonuclease at NMR frequencies 22, 75, and 90 MHz was studied by proton magnetic relaxation. It has been found that the pattern of proton relaxation in denaturated macromolecule is determined by slow exchange tau M approximately 10(-2)--10(-3) sec of "rigidly bound" water molecules and the solvent as a whole.
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PMID:[Magnetic proton relaxation of aqueous solutions of ribonuclease in the temperature region of intramolecular melting]. 713 22

The paper describes a method for preparing extracellular alkaline ribonuclease from Bacillus intermedius (EC 3.1.4.23). The method consists of acid treatment of the culture fluid for selective inactivation of the interfering enzymes, concentration of the enzymic protein by ammonium sulfate precipitation, dialysis against water, chromatography on DEAE-cellulose and phosphocellulose in the steady state, rechromatography on a phosphocellulose containing column, desalting and freeze-drying of the end product. Experimental samples of ribonuclease of 92% purity have been thus obtained.
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PMID:[Isolation and purification of alkaline ribonuclease from Bacillus intermedius]. 724 46

The interactions between proteins and solvent components have been investigated for the sucrose/water system. Thermodynamic and kinetic measurements of the thermal unfolding of alpha-chymotrypsin, chymotrypsinogen, and ribonuclease were performed as a function of sucrose concentration. The alteration in protein-solvent interactions in the presence of sucrose was also studied by density measurements and analyzed by multicomponent thermodynamic theory. Sucrose does not induce a conformational change in three proteins studied, although it does induce a small change in the circular dichroism spectrum of ribonuclease. The enthalpy of thermal unfolding shows little dependence on the concentration of sucrose, while the apparent activation energy of the unfolding process is increased by the addition of sucrose. The results from the protein-solvent interaction study indicate that sucrose is preferentially excluded from the protein domain, increasing the free energy of the system. Thermodynamically this leads to protein stabilization since the unfolded state of the protein becomes thermodynamically even less favorable in the presence of sucrose. The exclusion of sucrose from the protein domain seems to be related to the higher cohesive force of the sucrose water solvent system since all the experimental observations can be correlated with the effect of sucrose on the surface tension of water.
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PMID:The stabilization of proteins by sucrose. 725 92


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