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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A study has been made on the changes in the enzymatic activity of Ribonuclease-A**-(RNase-A) exposed to highly acidic (pH less than 1) acqueous environment. Irreversible alterations of activity were observed when the protein was exposed to an acidic medium for a long period (20 to 60 h). Even prior to these changes in activity RNase-A was found to form intermediates which had very nearly the same activity as the native protein. The primary process in the acid denaturation of RNase-A was observed to be deamidation of the protein leading to the formation of active chromotographically distinct derivatives. The initial product of deamidation, a monodeamidated derivative, has been isolated by chromatography on Amberlite XE-64. This initial deamidation reaction proceeded with very high specificity. The subsequent deamidation reaction is comparatively slower, so that nearly 50% of the native protein could be converted to this derivative before any subsequent deamidation took place. This monodeamidated derivative has been designated RNase-Aa1. The conversion of RNase-A to RNase-Aa1 was not accompanied by any changes in the primary structure other than the observed deamidation. Apart from the differences in chromatographic and electrophoretic mobilities, RNase-Aa1 was found to have very nearly the same activity and physicochemical properties as the native enzyme. Significance of this specific and faster deamidation of RNase-A in this denaturing medium as well as the biological significance of such deamidation reactions of proteins are discussed.
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PMID:Deamidated active intermediates in the irreversible acid denaturation of ribonuclease-A. 0 96

In an investigation into the disturbances of body function associated with burn injury we have measured the activity of alkaline ribonuclease (EC 3.1.4.22) and the level of urate in the serum and urine of patients sustaining burn injury. Ribonuclease activity was elevated in all patients. The degree of elevation can be related to the percentage of the body surface area burned and to a predictive index of burn mortality. Increased serum ribonuclease activity was accompanied by increased urine ribonuclease output. The relationship between serum urea and ribonuclease activity has been investigated. A significant correlation between these two parameters was observed during the first week post burn. We suggest that this correlation shows as a result of increased protein catabolism and renal dysfunction. After the first week a significant correlation between serum urea and ribonuclease activity was not observed. It is possible that, at this stage, increased ribonuclease activity is perhaps a result of tissue repair. Serum urate was found to be decreased in all patients after burn injury. Serum urate decrease expressed as a percentage of initial value, correlated very strongly with the predictive index of burn mortality. In severely burned patients the decrease in serum urate was accompanied by increased urine urate output and may indicate a change in renal handling of urate after burn injury.
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PMID:Observations on serum and urine alkaline ribonuclease activity and urate after burn injury in man. 2 22

A variety of proteins have been studied for their ability to interact and alter the thermotropic properties of phospholipid bilayer membranes as detected by differential scanning calorimeter. The proteins studied included: basic myelin protein (A1 protein), cytochrome c, major apoprotein of myelin proteolipid (N-2 apoprotein), gramicidin A, polylysine, ribonuclease and hemoglobin. The lipids used for the interactions were dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol. The interactions were grouped in three catagories each having very different effects on the phospholipid phase transition from solid to liquid crystalline. The calorimetric studies were also correlated with data from vesicle permeability and monolayer expansion. Ribonuclease and polylysine which exemplify group 1 interactions, show strong dependence on electrostatic binding. Their effects on lipid bilayers include an increase in the enthalpy of transition (deltaH) accompanied by either an increase or no change in the temperature of transition (Tc). In addition, they show minimal effects on vesicle permeability and monolayer expansion. It was concluded that these interactions represent simple surface binding of the protein on the lipid bilayer without penetration into the hydrocarbon region. Cytochrome c and A1 protein, which exemplify group 2 interactions, also show a strong dependence on the presence of net negative charges on the lipid bilayers for their binding. In contrast to the first group, however, they induce a drastic decrease in both Tc and deltaH of the lipid phase transition. Furthermore, they induce a large increase in the permeability of vesicles and a substantial expansion in area of closely packed monolayers at the air-water interface. It was concluded that group 2 interactions represent surface binding followed by partial penetration and/or deformation of the bilayer. Group 3 interactions, shown by proteolipid apoprotein and gramicidin A, were primarily non-polar in character, not requiring electrostatic charges and not inhibited by salt and pH changes. They had no appreciable effect on the Tc but did induce a linear decrease in the magnitude of the deltaH, proportional to the percentage of protein by weight. Membranes containing 50% proteolipid protein still exhibited a thermotropic transition with a deltaH one half that of the pure lipid, and only a small diminution of the size of the cooperative unit. It was concluded that in this case the protein was embedded within the bilayer, associating with a limited number of molecules via non-polar interactions, while the rest of the bilayer was largely unperturbed.
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PMID:Effects of proteins on thermotropic phase transitions of phospholipid membranes. 5 74

Ribonuclease (Ribonucleate nucleotide 2'-transferase E.C. 2.7.7.17) activity in serum of patients with chronic granulocytic leukaemia measured at pH 4.5-6.0 amounts to more than three times of that in serum of healthy subjects. At pH 6.0-8.0 the elevation of ribonuclease activity in serum of patients with chronic granulocytic leukaemia is less pronounced and amounts to about two times of that in normal ones. Using chromatography on CM Sephadex C-50 column, serum ribonuclease of both normal and chronic granulocytic leukaemia patients was separated into five distinct fractions. In serum of healthy subjects ribonuclease fractions denoted I-V contribute to 10; 21; 29; 22, and 18 percent of the total ribonuclease activity. In the serum of patients with chronic granulocytic leukaemia a decrease in ribonuclease fraction III to merely 17 percent and an increase in contribution of fraction IV to 32 percent of total ribonuclease activity could be observed. The comparison of each individual concentration of fraction in normal and leukaemia patients serum reveals, that ribonuclease fraction IV will increase about 3 times. A less pronounced increase could also be found for fractions I, II and V. However, ribonuclease fraction IV may be supposed to carry more than 50 percent of the whole extra load of ribonuclease present in the serum of chronic granulocytic leukaemia patients.
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PMID:Elevation of an acid ribonuclease in serum of patients with chronic granulocytic leukaemia. 8 84

A cross-linked dimer of pancreatic ribonuclease A (ribonucleate 3'-pyrimidino-olitonucleotidohydrolase, EC 3.1.4.22), at a 10 mg/liter concentration, blocks proliferation of tumor cells. The protein retains this ability after inactivation by iodoacetate. The cytostatic effect of ribonuclease preparations on various cell lines correlates well with their rate of uptake: for example, monomeric ribonuclease A is much less effective and is taken up into the cells 10 t0 15 times more slowly. Cell fractionation studies on hepatoma cells indicate accumulation of the dimer in the lysosomal system. Ribonuclease dimer induces a labilization of the lysosomes when added to cell homogenates, raising the possibility that its antitumoral effect may be mediated by endocytosis and lysosomes.
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PMID:Inhibition of tumor cell proliferation by dimerized ribonuclease. 17 14

Pseudomonas aeruginosa (ATCC 9027) releases four periplasm-located enzymes, i.e., ribonuclease (EC 3.1.4.22; EC 3.1.4.23), alkaline phosphatase (EC 3.1.3.1), cyclic-2', 3'-phosphodiesterase (EC 3.1.4.d), and 5'-nucleotidase (EC 3.1.3.5) into the medium during growth. Ribonuclease and alkaline phosphatase are classed as enzymes which are readily extracted by osmotic shock and spheroplast formation whereas cyclic-2',3'-phosphodiesterase and 5'-nucleotidase are classed as enzymes which are not readily extracted by these procedures. In view of the relative ease of extraction of the former enzymes it is suggested that the lattter enzymes, cyclic-2',3'-phosphodiesterase and 5'-nucleotidase, are bound and located in the periplasm in a manner different to ribonuclease and alkaline phosphatase.
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PMID:The release and characterization of some periplasm-located enzymes of Pseudomona aeruginosa. 18 95

Quantitative changes of various forms of ribonucleic acids [nuclear (n-RNA), ribosomal (r-RNA), transport (t-RNA)] as well as ribonuclease activity have been studied in rat brain, in its nuclear, ribosomal and supernatant fractions following 3,5-cyclic AMP (c-AMP) and S-adenosyl-L-methionine. These substances were shown to raise the levels of r-RNA in brain and reduce the amount of n-RNA of GC type. c-AMP was also found to reduce the n-RNA of AU type and t-RNA in brain, while S-adenosyl-L-methionine does not affect n-RNA of AU type and raises considerably t-RNA. S-adenosyl-L-methionine has been found to raise the levels of all kinds of RNA while c-AMP has no effect. Ribonuclease activity of nuclear, ribosomal and supernatant fractions (105,000 g) of brain has been found to be enhanced by c-AMP while S-adenosyl-L-methionine raises ribonuclease activity of ribosomal fraction only at pH 7.9. The data obtained indicate that c-AMP and S-adenosyl-L-methionine are of importance in the mechanisms regulating the level of nucleic acids and activity of enzymes involved in their metabolism.
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PMID:[Concentration of different forms of RNA in the brain and ribonuclease activity of the nuclear, ribosomal and supernatant fractions of brain tissue following the action of cyclic adenosine-3',5'-monophosphate and S-adenosyl-L-methionine]. 18 41

Serum Ribonuclease (RNase, EC. 3. 1. 4. 22) of normal persons and of patients with chronic pancreatitis, or pancreatic cancer was determined with poly (C) as substrate. Strikingly abnormal elevations occured in the serum RNase of patients with pancreatic cancer (p less than 0.001). Average serum RNase values of 18 normal persons, 10 patients with chronic pancreatitis and 26 patients with pancreatic cancer were 92, 118, and 249 units, respectively. In patients with pancreatic cancer, we compared the RNase level with four histologic types (ductar cell adenocarcinoma, anaplastic cell carcinoma, acinar cell carcinoma, and islet cell carcinoma). Adenocarcinoma showed higher activity than the other histologic types (p less than 0.005). When we compared the serum of pancreatic cancer and pancreatic cancer tumor extract with normal serum and normal pancreas extract, strikingly different phosphocellulose chromatographic pattern were evident. The correlation of increased serum RNase levels with tumor histology and different chromatographic pattern may explain the new enzyme production in cancer patients, and have biological significance in the development of pancreatic cancer.
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PMID:Serum ribonucleases in pancreatic cancer: relation to tumor histology. 21 87

The deuterium exchange kinetics of the C(2) protons of the four histidine residues of native bovine pancreatic ribonuclease A have been followed at pH 6.5 and 8.0 by proton magnetic resonance spectroscopy (1H NMR). Comparison of the order of exchange of the histidine peaks with tritium exchange rates into individual histidine residues [Ohe, M., Matsuo, H., Sakiyama, F., and Narita, K. (1974), J. Biochem. (Tokyo) 75, 1197] supports the previous assignment of histidine NMR peaks H(1) and H(4) to histidine-105 and histidine-48 but requires reassignment of peaks H(2) and H(3) to histidine-119 and histidine-12, respectively. Ribonuclease A samples having differentially deuterated histidines have been used to verify the existence of crossover points in the histidine proton magnetic resonance titration curves and to observe the discontinuous titration curve of histidine-48. Proton magnetic resonance peaks have been assigned to the C(4) protons of the four histidine residues of ribonuclease A on the basis of their unit proton areas and by matching their titration shifts with the more readily visible C(2)-H peaks of the histidines. The pK' values derived from the C(4)-H data agree, within experimental limits, with those derived from C(2)-H data. The C(4)-H peaks were assigned to histidine-12, -48, -105, and -119 of ribonuclease A on the basis of their pH dependence, pK' values, shifts of their pK' values in the presence of inhibitor cytidine 3'-phosphate, and by comparison with the assignments of the histidine C(2)-H peaks above.
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PMID:Correlation proton magnetic resonance studies at 250 MHz of bovine pancreatic ribonuclease. I. Reinvestigation of the histidine peak assignments. 24 Mar 82

Suspensions of rat pancreatic microsomal fraction release alpha-amylase and ribonuclease on incubation at 37 degrees C, but not at 2 degrees C. The release is abolished by proteolytic enzymes. Ribonuclease associated with the microsomal fraction is protected from subtilisin BPN' attack, but is sensitive after release.
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PMID:Proteinase-sensitive release of enzymes from pancreatic microsomal fraction. 31 Nov 98


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