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 diagnostic value of the low-molecular mass proteins ribonuclease, beta 2-microglobulin, and lysozyme in serum for the detection of reduced glomerular filtration rates was evaluated. The values of these proteins and of serum creatinine investigated in 52 patients suffering from chronic renal diseases were plotted against 99m-Tc-diethylenetriaminopentaacetate clearance as an indicator of glomerular filtration rate. Log-transformed data showed a good fit of linearity. Considering the 95% confidence limits of the regression equations, ribonuclease increased above the normal range when the glomerular filtration rate was lower than 1.24 ml/s whereas the other analytes partly remained within their normal limits. Out of those 18 patients with glomerular filtration rates lower than 1.24 ml/s, all patients showed elevated ribonuclease levels. beta 2-Microglobulin, creatinine, and lysozyme were increased in 17, 14, and 12 cases, respectively. Ribonuclease and beta 2-microglobulin showed similar results when other diagnostic criteria (specificity, efficiency and predictive values) were taken into account. We recommend ribonuclease determination in serum for the detection of reduced glomerular filtration rate in the normal range of creatinine. The test is diagnostically powerful, cheap and easy to perform.
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PMID:Diagnostic value of low-molecular mass proteins in serum for the detection of reduced glomerular filtration rate. 332 Feb 63

Previous studies have indicated that at least part of the selection of proteins for degradation takes place at a binding site on ubiquitin-protein ligase, to which the protein substrate is bound prior to ligation to ubiquitin. It was also shown that proteins with free NH2-terminal alpha-NH2 groups bind better to this site than proteins with blocked NH2 termini (Hershko, A., Heller, H., Eytan, E., and Reiss, Y. (1986) J. Biol. Chem. 261, 11992-11999). In the present study, we used simple derivatives of amino acids, such as methyl esters, hydroxamates, or dipeptides, to examine the question of whether the protein binding site of the ligase is able to distinguish between different NH2-terminal residues of proteins. Based on specific patterns of inhibition of the binding to ligase by these derivatives, three types of protein substrates could be distinguished. Type I substrates are proteins that have a basic NH2-terminal residue (such as ribonuclease and lysozyme); these are specifically inhibited by derivatives of the 3 basic amino acids (His, Arg, and Lys) with respect to degradation, ligation to ubiquitin, and binding to ligase. Type II substrates (such as beta-lactoglobulin or pepsinogen, that have a Leu residue at the NH2 terminus) are not affected by the above compounds, but are specifically inhibited by derivatives of bulky hydrophobic amino acids (Leu, Trp, Phe, and Tyr). In these cases, the amino acid derivatives apparently act as specific inhibitors of the binding of the NH2-terminal residue of proteins, as indicated by the following observations: (a) derivatives in which the alpha-NH2 group is blocked were inactive and (b) in dipeptides, the inhibitory amino acid residue had to be at the NH2-terminal position. An additional class (Type III) of substrates comprises proteins that have neither basic nor bulky hydrophobic NH2-terminal amino acid residues; the binding of these proteins is not inhibited by homologous amino acid derivatives that have NH2-terminal residues similar to that of the protein. It is concluded that Type I and Type II proteins bind to distinct and separate subsites of the ligase, specific for basic or bulky hydrophobic NH2-terminal residues, respectively. On the other hand, Type III proteins apparently predominantly interact with the ligase at regions of the protein molecule other than the NH2-terminal residue.
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PMID:Specificity of binding of NH2-terminal residue of proteins to ubiquitin-protein ligase. Use of amino acid derivatives to characterize specific binding sites. 334 27

Thermal unfolding of ribonuclease, lysozyme, chymotrypsinogen, and beta-lactoglobulin was studied in the absence or presence of poly(ethylene glycols). The unfolding curves were fitted to a two-state model by a nonlinear least-squares program to obtain values of delta H, delta S, and the melting temperature Tm. A decrease in thermal transition temperature was observed in the presence of poly(ethylene glycol) for all of the protein systems studied. The magnitude of such a decrease depends on the particular protein and the molecular size of poly(ethylene glycol) employed. A linear relation can be established between the magnitude of the decrease in transition temperature and the average hydrophobicity of these proteins; namely, the largest observable decrease is associated with the protein of the highest hydrophobicity. Further analysis of the thermal unfolding data reveals that poly(ethylene glycols) significantly effect the relation between delta H degrees of unfolding and temperature for all the proteins studied. For beta-lactoglobulin, a plot of delta H versus Tm indicates a change in slope from a negative to a positive value, thus implying a change in delta Cp in thermal unfolding caused by the presence of poly(ethylene glycols). Results from solvent-protein interaction studies indicate that at high temperature poly(ethylene glycol) 1000 preferentially interacts with the denatured state of protein but is excluded from the native state at low temperature. These observations are consistent with the fact that poly(ethylene glycols) are hydrophobic in nature and will interact favorably with the hydrophobic side chains exposed upon unfolding; thus, it leads to a lowering of thermal transition temperature.
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PMID:Thermal stability of proteins in the presence of poly(ethylene glycols). 342 6

With the synthesis of a new, strongly basic Immobiline (pK 10.3 at 10 degrees C) it has been possible to formulate a new pH 10-11 recipe for focusing very alkaline proteins, not amenable to fractionation with conventional isoelectric focusing in carrier ampholyte buffers. In this formulation, water is added as an acidic Immobiline having pK = 14 and a unit molar concentration (or with a pK = 15.74 and standard 55.56 molarity) since around pH 11 its buffering power becomes significant. The gel contains a 'conductivity quencher', i.e. a density gradient incorporated in the matrix, with the dense region located on the cathodic side (pH 11) for (a) smoothing the voltage gradient on the separation cell and (b) reducing the anodic electrosmotic flow due to the net positive charge acquired by the matrix at pH 11 (1 mM excess protonated amino groups to act as counterions to the 1 mm OH- groups in the bulk water solution generated by the local value of pH 11). Excellent focusing is obtained for such alkaline proteins as lysozyme (pI 10.55), So-6 (a leaf protein, pI 10.49), cytochrome c (pI 10.45) and ribonuclease (pI 10.12).
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PMID:Isoelectric focusing in immobilized pH gradients in the pH 10-11 range. 342 69

The coefficient of compactness was recently introduced and used to locate domains in lysozyme and ribonuclease (Zehfus and Rose: Biochemistry 25:5759-5765, 1986). Nineteen additional proteins now have been analyzed by using this measure. Complete listings of compact units and plots showing their hierarchic organization are presented for all twenty-one proteins. Large compact units correspond well to protein domains; however, many smaller compact structures of equal or better compactness are also found. Since small compact units could represent subdomains or protein-folding intermediates, their structural composition is further examined.
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PMID:Continuous compact protein domains. 344 75

The capability of dietary selenium (Se) to augment the immune response was evaluated in 96 crossbred weanling swine. Six groups of 16 pigs were fed diets with Se supplemented as sodium selenite at 0, 0.3, 0.6, 0.9, 1.2, and 1.5 mg/kg. The basal diet contained 0.068 mg of Se/kg. Weight gain, feed consumption, and feed efficiency were similar for all diets. Whole blood concentrations of Se linearly increased as the dietary concentrations of Se increased. The humoral response was monitored by immunoglobulin G titers to lysozyme and ribonuclease, using an enzyme-linked immunosorbent assay. Although no significant difference in immunoglobulin G titers to either antigen was detected among diets, a similar trend in antibody response was noted. The diet with 0.9 mg of added Se/kg produced the highest antibody response to both antigens, whereas the diet with 0.3 mg of added Se/kg produced the lowest titers for both antigens. Cell-mediated immunity was evaluated in the pigs by the dermal response to phytohemagglutinin. Significant difference was not detected in pigs fed the various diets in terms of the mean diameters of their dermal reactions to phytohemagglutinin injections. Although blood concentrations of Se were increased, rate and efficiency of weight gain and humoral and cell-mediated immunity were not significantly improved by adding 0.3 to 1.5 mg of Se/kg to diets.
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PMID:Immunomodulation in weanling swine with dietary selenium. 348

The amino-terminal 20 amino acids are required for microinjected ribonuclease A (RNase A) to be taken up by lysosomes and degraded at an enhanced rate during serum withdrawal. We used water-soluble carbodiimides to covalently attach the RNase S-peptide (residues 1-20) to [3H]RNase S-protein (residues 21-124) at unspecified locations. We then measured catabolism of the [3H]S-protein-S-peptide conjugate after its microinjection into human diploid fibroblasts. The attached S-peptide caused the degradation of S-protein to be enhanced 2-fold in the absence of serum. Control experiments showed that degradation of [3H]RNase S-protein remained unresponsive to serum after conjugation with the inactive fragment, RNase S-peptide (residues 1-10). Covalent attachment of RNase S-peptide had a similar effect on the catabolism of two other proteins. Degradation rates of microinjected 125I-labeled lysozyme and 125I-labeled insulin A chain are normally unresponsive to serum withdrawal. However, breakdown rates of microinjected 125I-labeled lysozyme-S-peptide and 125I-labeled insulin A chain-S-peptide conjugates were increased 2-fold during serum deprivation. We suggest that RNase S-peptide acts as a "single sequence" that directs cytosolic proteins to lysosomes through a pathway that is activated by deprivation conditions.
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PMID:Covalent linkage of ribonuclease S-peptide to microinjected proteins causes their intracellular degradation to be enhanced during serum withdrawal. 352 40

Two developments have enabled major advancements in the use of capillary gas chromatography (GC), the result being its much more widespread use in investigations on a broad range of chemical and biological problems. The 2 technological developments were the introduction of fused silica capillary columns and the development of immobilized stationary phases for capillary GC columns. Because fused silica columns with immobilized stationary phases of varying polarities are offered by numerous vendors of chromatographic equipment, they have become widely used for many analytical tasks. We conducted a study to compare the effectiveness of commercially available fused silica capillary columns with the classical ion-exchange method in the separation and quantitation of amino acids. We selected the N-trifluoroacetyl (TFA) n-butyl and the N-heptafluorobutyryl (HFB) isobutyl ester derivatives for this study because of the extensive research and application of these derivatives during the past 20 years. The amino acid content of hydrolysates of 5 materials was measured: ribonuclease, beta-lactoglobulin, lysozyme, soybean meal, and a commercial poultry feed. Single 6N HCl hydrolysates of each material were prepared to minimize sample preparation differences, and 3 independent analyses of each hydrolysate were made by each of 3 techniques: the N-TFA n-butyl and N-HFB isobutyl ester methods using capillary gas chromatography and the ion-exchange chromatographic method using a Beckman 121 M amino acid analyzer. Our results clearly demonstrate that capillary GC analysis of amino acids using fused silica bonded-phase columns provides data with good precision and in general excellent agreement with ion-exchange analyses.
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PMID:Amino acid analysis by capillary gas chromatography. 357 Nov 20

The glycation (nonenzymatic glycosylation) of several proteins was studied in various buffers in order to assess the effects of buffering ions on the kinetics and specificity of glycation of protein. Incubation of RNase with glucose in phosphate buffer resulted in inactivation of the enzyme because of preferential modification of lysine residues in or near the active site. In contrast, in the cationic buffers, 3-(N-morpholino)propane-sulfonic acid and 3-(N-tris(hydroxymethyl)methyl-amino)-2-hydroxypropanesulfonic acid, the kinetics of glycation of RNase were decreased 2- to 3-fold, there was a decrease in glycation of active site versus peripheral lysines, and the enzyme was resistant to inactivation by glucose. The extent of Schiff base formation on RNAse was comparable in the three buffers, suggesting that phosphate, bound in the active site of RNase, catalyzed the Amadori rearrangement at active site lysines, leading to the enhanced rate of inactivation of the enzyme. Phosphate catalysis of glycation was concentration-dependent and could be mimicked by arsenate. Phosphate also stimulated the rate of glycation of other proteins, such as lysozyme, cytochrome c, albumin, and hemoglobin. As with RNase, phosphate affected the specificity of glycation of hemoglobin, resulting in increased glycation of amino-terminal valine versus intrachain lysine residues. 2,3-Diphosphoglycerate exerted similar effects on the glycation of hemoglobin, suggesting that inorganic and organic phosphates may play an important role in determining the kinetics and specificity of glycation of hemoglobin in the red cell. Overall, these studies establish that buffering ions or ligands can exert significant effects on the kinetics and specificity of glycation of proteins.
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PMID:Effect of phosphate on the kinetics and specificity of glycation of protein. 358 12

Fourier transform-infrared (FT-IR) spectra are reported for the amide III spectral region of the native and thermally denatured forms of chymotrypsinogen, ribonuclease, bovine serum albumin, and lysozyme. Chymotrypsinogen denatures into structures containing substantial contributions from beta-sheets, while lysozyme and bovine serum albumin show increased amounts of random-coil forms. The changes observed for ribonuclease are quite small. Bovine serum albumin shows at least six bands in the 1,260-1,320 cm-1 region which undergo large intensity changes upon thermal denaturation, and hence are assignable to alpha-helical amide III modes. The large number of observed bands suggests that slight variations in helical geometry, symmetry, or interactions result in changed amide III frequencies, so that simple correlations between narrow frequency ranges and secondary structures may not be applicable for this mode. A widened frequency range is suggested as diagnostic for helical structures.
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PMID:Thermal denaturation of globular proteins. Fourier transform-infrared studies of the amide III spectral region. 360 22


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