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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure for the preparation of porcine protease E is described. The availability of a convenient source of the enzyme has permitted specificity studies utilizing the macromolecular substrates oxidized insulin A and B chains and oxidized ribonuclease. The results show that protease E has a pronounced selectivity for the carbonyl bonds of serine threonine, alanine, and valine residues, with the latter most favored. The specificity is complementary to that of the chymotrypsins and we suggest that this property is physiologically significant. The k3 and Km values for the substrates acetyl-trialanine methyl ester, succinyltrialanine p-nitroanilide and benzoylalanine methyl ester are comparable to those observed by others for porcine elastase. The specificity observed in the present work, however, indicates that protease E may best be regarded as a member of the chymotrypsin group of enzymes.
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PMID:The specificity of porcine pancreatic protease E. 700 83

Laboratory tests are the object of continuous interest in acute as well as chronic pancreatic disease. Enzymic assays play an important role, particularly in screening for pancreatic disease. The diagnostic contribution of amylase, isoamylases, immunoreactive trypsin and lactoferrin, ribonuclease and galactosyltransferase, as well as the problem of chronic nonpancreatic hyperamylasemia is reviewed. Functional methods detect a normal or abnormal function and in this sense the results should be interpreted. Present evaluation of the pancreozymin-secretin test, the Lundh test, fecal chymotrypsin, determination of stimulated chymotrypsin secretion by peroral synthetic substrates marked with 4-aminobenzoic acid, duodenal excretion of 75Se-methionine and plasma pancreatic polypeptide is given. Up to now, immunologic methods have not fulfilled the expectations in spite of considerable attention paid to them in recent years.
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PMID:[Developments in the laboratory diagnosis of diseases of the exocrine pancreas (author's transl)]. 702 8

Thin sections of heat-set proteins gels formed from bovine serum albumin, insulin, lysozyme, ribonuclease, and alpha-chymotrypsin, have been studied by transmission electron microscopy. Micrographs have been interpreted as showing protein networks with strands between one and two times as thick as the native protein diameters. Considerable differences in the persistence characteristics, and frequencies of cross-linking, of the strands are observed, and there are variations in network homogeneity over long distances which correlate well with changes in gel opacity caused by alterations in pH and ionic strength. Evidence that artefacts are unlikely to have influenced these interpretations has been obtained in the BSA case in particular, by studying the aggregation process in solution, using alternative microscope approaches such as heavy-metal shadowing and negative staining. assuming that artefacts are absent, gel section micrographs have been simulated by a computer procedure, and the results suggest that, in most cases, the simplest interpretation of the microscope data is in terms of a "string of beads" model for the aggregation process, involving only moderately unfolded, and still globular, protein molecules. Other structural interpretations cannot be ruled out, however, as the degree of protein unfolding, and the exact mode of incorporation of the monomers into the network filaments, cannot be established by the microscope technique alone.
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PMID:Electron microscopy of network structures in thermally-induced globular protein gels. 702 72

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

A folate-binding protein (binder) from human choroid plexus was solubilized with Triton X-100 and partially purified in three steps: (1) affinity chromatography, (2) Sephadex G-200 column chromatography, and (3) polyacrylamide gel electrophoresis. When the partially purified binder was subjected to sodium dodecyl sulfate--polyacrylamide gel electrophoresis, the binding activity was located in the region of the gel with a molecular weight between 45,000 and 60,000. The specific activity of the binder after the three purification steps was 1.2 mu g folic acid/mg protein, a 316-fold purification. Binding activity of the partially purified binder decreased below pH 6.0 and above pH 8.0, was unaffected by treatment with ribonuclease or deoxyribonuclease, but was abolished with trypsin, chymotrypsin, or protease (Streptomyces griesus). The binding of folic acid to the human binder was inhibited by folate Greater Than H4-folate Greater Than methyl-H4-folate approximately dihydrofolate approximately pteroic acid Greater Than methotrexate approximately aminopterin.
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PMID:Partial purification and characterization of a folate-binding protein from human choroid plexus. 727 9

The effect of prolactin on the digestive potency of the acinar pancreas was examined in pituitary-grafted hyperprolactinemic mice, because our previous experiment showed that a marked proliferation of pancreatic acinar cells was induced by pituitary grafting in mice. To know whether the digestive function is modified, the tissue contents of pancreatic digestive enzymes, such as chymotrypsin, lipase alpha-amylase and ribonuclease, were measured in the hyperprolactinemic mice. Pituitary grafting significantly increased the contents of chymotrypsin and lipase in the pancreas on day 12 after the operation without affecting intake of food, when compared to those in the sham-operated controls. On day 30, however, the differences between pituitary-grafted and control mice were no more discernible. Thus, the digestive enzyme activities are easily modified soon after the increase of circulating prolactin level. This effect of prolactin on the function of the pancreas may be responsible for "homeorhetic" control of nutrients during lactation. In another set of experiments in adrenalectomized-castrated or castrated mice, pituitary grafting induced an increase in the weight of the pancreas. In addition, adrenalectomy in combination with castration did not alter the pancreatic contents of chymotrypsin and lipase but decreased the amylase content. These results taken together seem to indicate that the effect of prolactin on the exocrine pancreas is not mediated by gonadal and adrenal steroid hormones.
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PMID:Modification of pancreatic digestive function by pituitary grafting in mice. 765 48

A ribonuclease (RNase Oy) was purified to homogeneity on SDS-PAGE from the homogenate of oyster (Crussdstrea grigus). The apparent molecular weight estimated from SDS-PAGE was ca. 28 kDa. The pH optimum of the RNase was 5.0. The RNase released mononucleotides from RNA in the order of 3'-GMP, 3'-AMP, and 3'-UMP. The complete amino acid sequence of RNase Oy was determined, mostly by analyzing the peptides generated by BrCN cleavage or digestion by lysylendopeptidase, staphylococcal V8 protease, and alpha-chymotrypsin. The molecular weight of the protein moiety of RNase Oy deduced from the sequence was 24,359. The sequence of RNase Oy contained two typical histidine residues in segments common to the active site of RNase T2 family enzymes. The locations of six half cystine residues among eight were almost superimposable on those of four known plant RNases of RNase T2 family. The sequence homology between RNase Oy and five fungal and four plant RNases amount, to 43-56 amino acid residues. The amino acid sequence of the N-terminal part of RNase Oy is more similar to those of plant RNases than to those of fungal RNases. This RNase is the first RNase T2 family RNase from mollusc whose primary structure has been elucidated.
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PMID:Purification, some properties, and primary structure of a base non-specific ribonuclease from oyster (Crussdstrea grigus). 813 35

The percentage of bacteriocin-producing and phage-producing Klebsiella strains was as follows: K. pneumoniae-10%, K. ozaenae-7%, K. rhinoscleromatis-9%. The antimicrobial spectrum of the studied inducible particler was broad and was not limited by the frames of the genus and family. Bacteriocins and bacteriophages from Klebsiella were active to Klebsiella, Enterobacter, Escherichia, Shigella and Proteus representatives significant in medicine. Klebocins and Klebsiella phages exhibited antagonistic effects to phytopathogenic bacteria. Some strains of Erwinia and Pseudomonas were sensitive to phages or bacteriocins from Klebsiella. Bacteriocins protected corn and tomato seeds from contamination by erwinioses agents. All cultures of Agrobacterium, Corynebacterium, Micrococcus, Staphylococcus, Streptococcus were resistant to action of phages and klebocins. Bacteriocins from Klebsiella were assayed for their sensitivity to trypsin, chymotrypsin, lysozyme, ribonuclease, deoxyribonuclease. Action of klebocins was associated with a protein component. Proceeding from data of diffusion through the disc ultrafiltration membranes molecular weight of klebocins was in the range of 30,000 and 50,000 Da.
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PMID:[The antimicrobial spectrum of the action of bacteriocins and bacteriophages from Klebsiella strains]. 816 98

We have obtained unusual 'zig-zag' temperature dependencies of the rate constant of irreversible thermoinactivation (k(in)) of enzymes (alpha-chymotrypsin, covalently modified alpha-chymotrypsin, and ribonuclease) in a plot of log k(in) versus reciprocal temperature (Arrhenius plot). These dependencies are characterized by the presence of both ascending and descending linear portions which have positive and negative values of the effective activation energy (Ea), respectively. A kinetic scheme has been suggested that fits best for a description of these zig-zag dependencies. A key element of this scheme is the temperature-dependent reversible conformational transition of enzyme from the 'low-temperature' native state to a 'high-temperature' denatured form; the latter form is significantly more stable against irreversible thermoinactivation than the native enzyme. A possible explanation for a difference in thermal stabilities is that low-temperature and high-temperature forms are inactivated according to different mechanisms. Existence of the suggested conformational transition was proved by the methods of fluorescence spectroscopy and differential scanning calorimetry. The values of delta H and delta S for this transition, determined from calorimetric experiments, are highly positive; this fact underlies a conclusion that this heat-induced transition is caused by an unfolding of the protein molecule. Surprisingly, in the unfolded high-temperature conformation, alpha-chymotrypsin has a pronounced proteolytic activity, although this activity is much smaller than that of the native enzyme.
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PMID:Reversible conformational transition gives rise to 'zig-zag' temperature dependence of the rate constant of irreversible thermoinactivation of enzymes. 830 89

Prior studies have revealed the presence of chymotrypsinlike protease in peripheral organs, although no definitive evidence for the synthesis of this enzyme in tissue other than the pancreas is available. In an attempt to detect chymotrypsinogen mRNA in peripheral organs, a fragment of the pancreatic chymotrypsin mRNA from rat was amplified using PCR. The sequence was identified as a portion of the rat chymotrypsin B gene overlapping exon 5 through exon 7. It was subcloned into the pGEM-4Z vector and used as a template for the vitro transcription of an antisense riboprobe. Using ribonuclease protection and Northern blot analyses, chymotrypsin mRNA was detected in the rat pancreas, stomach, duodenum, ovary, and spleen. Monoclonal and polyclonal antisera against chymotrypsin detected chymotrypsinlike immunoreactivity in rat and human pancreas, rat stomach, duodenum and jejunum. Electrophoresis and immunoblotting revealed chymotrypsin-chymotrypsinogen bands (25-29 kDa) in the stomach and duodenum. Synthesis of a potent protease such as chymotrypsin in tissue other than pancreas is significant, suggesting a potential physiological and/or pathological role in these tissues.
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PMID:Chymotrypsin gene expression in rat peripheral organs. 956 Apr 77


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