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:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

By sequential acid treatment, gel filtration and KM-cellulose sorption a 18--20-fold purified preparation of ribonuclease with a yield of 50--60% was obtained from the culture liquid filtrate of Actinomyces rimosus 994. The preparation had a high specific activity of 450,000--600,000 units/mg protein, contained 85--98% protein, insignificant amounts of carbohydrates and hydroxytetracycline, and no quantities of DNase, phosphomonoesterases, phosphodiesterase or proteases. In RNA degradation (preparation of the total yeast RNA of the Sigma Co.) optimal results were obtained at 50 degrees C and pH 7.0--7.2 in phosphate buffer and 7.6--8.0 IN Tris-HCl buffer. The preparation was stable at high temperatures (80--100 degrees) in the wide pH range and during storage in the lyophilized form and in buffer solutions. RNase effect was inhibited by zinc, copper, iron and cobalt cations and activated by beta-mercaptoethanol, citrate and EDTA. Protamine sulphate and urea in low concentrations (0.01% and 1--4 M, respectively) accelerated and in high concentrations (1% and 8 M, respectively) terminated the enzyme reaction. With respect to many properties RNase from Act. rimosus 994 was similar to extracellular RNases, produced by other actinomycetes and fungi.
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PMID:[Preparation of extracellular ribonuclease form Actinomyces rimosus 994]. 3 16

By application of electron cytochemical techniques to cerebellar tissue, the presence of proteoglycans was demonstrated at the axoplasmic matrix of mossy fiber endings. Blocks of glutaraldehyde (G) fixed mouse cerebellum were processed according to the following procedures: a) Some pieces of tissue were post-fixed in osmium tetroxide, dehydrated by ethanol and embedded in araldite. b) Other pieces were sectioned to 30 mum thick and then immersed in Alcian blue solution pH = 2.7 followed by osmium tetroxide fixation, dehydrated and embedded in araldite (GABOUL procedure). c) Parallel slices of (b) previous to Alcian blue immersion were washed and incubated in either methanol-HCl, neuraminidase, ribonuclease or testicular hyaluronidase with their respective controls. d) Other blocks of G fixed tissue without any other treatment and fixation were dehydrated and embedded in araldite. Ultrathin sections of a, b and c were doubly stained with uranyl acetate and lead citrate while ultrathin sections of (d) were stained with the osmium coordination compound Os-DMEDA. The electron microscopic study revealed at the presynaptic axoplasm of mossy fiber rosettes, the presence of a GABOUL and Os-DMEDA positive electron dense material surrounding synaptic vesicles and continuous with presynaptic dense projections. This material which coincides with cytonet distribution was resistant to neuraminidase and ribonuclease and sensible to hyaluronidase and carboxymethylation. These findings permit us to conclude that the axoplasmic material of mossy fiber endings is constituted by proteoglycans in which hyaluronic acid and chondroitin 4-and/or 6-sulphate are present. The probable importance of these proteoglycans in synaptic mechanisms is also discussed.
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PMID:Electron microscopic demonstration of hyaluronidase sensible proteoglycans at the presynaptic area in mouse cerebellar cortex. 6 92

Purification and partial characterization of the poliovirus RNA-linked protein (VPg) are described. VPg has been freed from the RNA by ribonuclease digestion and phenol extraction. Gel filtration chromatography of VPg-pUp (labeled with 32P) in 0.5% sodium dodecyl sulfate or 6 M guanidine HCl indicates that it has a molecular weight of about 12,000. VPg is bound to the 5' end of poliovirion RNA by a phosphodiester bond between a tyrosine residue in the VPg molecule and the 5'-terminal uridine. After acid hydrolysis of [3H]tyrosine-labeled VPg-pU, free tyrosine can be released by venom phosphodiesterase. Acid hydrolysis of VPg-p labeled with either 32P or [3H] tyrosine yields tyrosine-phosphate. There appears to be only 1 tyrosine residue per VPg molecule.
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PMID:Protein is linked to the 5' end of poliovirus RNA by a phosphodiester linkage to tyrosine. 20 34

The in vitro folding kinetics of a fragment corresponding to an intact dimer of the Cgamma3 domain of human IgG1 (pFc') were monitored via the large changes in tryptophan fluorescence which accompany these processes. In going from the guanidine hydrochloride (Gdn.HCl) induced unfolded state (4.0 M Gdn.HCl) to the native state (0.5 M Gdn.HCl), three well-separated first-order processes were observed having time constants of 5, 50, and 350 s and roughly equal amplitudes. These values were concentration independent, a fact consistent with there being no fluorescence change accompanying dimerization. These time constants are one to two orders of magnitude slower than those observed for proteins of similar size such as ribonuclease or cytochrome c, most probably reflecting the complex processes involved in forming the correct beta-sheet arrangement of immunoglobulin domains. The corresponding unfolding transition is biphasic having time constant values of 50 and 500 s, the latter comprising 80% of the fluorescence change. These data indicate the presence of at least one species with intermediate fluorescence along the unfolding pathway. Gdn.HCl concentration jumps were also performed over various intervals within the transition zone. The results are not consistent with a fully reversible mechanism. In the absence of the intrachain disulfide bond, pFc' exists in an unfolded state even at 0.5 M Gdn.HCl. In a concomitant refolding and reoxidation experiment (at 0.5 M Gdn.HCl and using an optimal disulfide interchange catalytic system), the time constant for disulfide formation was in the range of 80--200 s and the fluorescence change revealed a lag phase analyzable in terms of rate-limiting reoxidation and refolding times consistent with those observed for the initially disulfide bonded species. Under similar conditions but a 4 M Gdn.HCl, reoxidation was more than two orders of magnitude slower, suggesting that reoxidation is directed by a refolding nucleation event.
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PMID:Folding pathways of immunoglobulin domains. The folding kinetics of the Cgamma3 domain of human IgG1. 46 72

The rate of hydrolysis of protein-methyl ester, the enzymatic product of S-adenosylmethionine: protein-carboxyl methyltransferase (EC.2.1.1.24) acting on oxidized ribonuclease, was measured at pH 7.1 and 8.6 at 37 degrees C. The half-life of the hydrolysis of the ester is 25 min at pH 7.1, and 4 min at 8.6. The rate of hydrolysis of the enzymatically formed esters at pH 7.0, in 0.1 M phosphate buffer, was about 25 times faster than that of esters formed chemically by reaction with methanol in HCl. The lability of the enzymatically synthesized protein-methyl ester suggests that the esterification is specific to sites such that ionization of neighboring amino acid side chains enhances the rate of the hydrolysis.
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PMID:Labile protein-methyl ester: comparison between chemically and enzymatically synthesized. 95 34

The synthesis of cytidylyu-(3,-5,)-cytidine (CpC) catalyzed by pancreatic ribonuclease at 23 degrees, 0 degrees, and -15 degrees C in Tris-HCl-buffer was compared with that in aqueous propan-2-0. The data obtained show that the increase in the yield of oligonucleotides in aqueous buffer at -15 degrees, observed earlier is rather a result of the concentration change in the reaction mixture caused by the freezing of water than by a temperature fall from 0 to -15 degrees. A 4-fold increase in the initial concentrations of the substrates and ribonuclease with respect to the concentrations used earlier leads to the yield of CC in a homogeneous solution at 0 degrees close to is yield found in the frozen mixture at -15 degrees.
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PMID:[Effect of temperature and concentrations of initial components on synthesis of internucleotide bond catalyzed by pancreatic ribonuclease]. 120 86

Porcine ribonuclease inhibitor (RI) contains 30 1/2-cystinyl residues, all of which occur in the reduced form. Reaction of the native protein with 5,5'-dithiobis (2-nitrobenzoic acid) resulted in the release of 30 mol of the product 5-mercapto-2-nitrobenzoate, and the loss of the RNase inhibitory activity. A linear relationship between the degree of modification and inactivation was observed. The rate of modification was greatly increased in the presence of 6 M guanidinium HCl. Reaction with substoichiometric amounts of 5,5'-dithiobis(2-nitrobenzoic acid) was found to yield a mixture of fully reduced active molecules, and fully oxidized inactive ones, but no partially oxidized forms were detected. This suggests that an "all-or-none" type of modification and inactivation took place. All 1/2-cystinyl residues in the inactive, monomeric inhibitor had formed disulfide bridges, judged by the absence of either free thiol groups or mixed disulfides with 5-mercapto-2-nitrobenzoate. This fully disulfide-cross-linked molecule had an open conformation compared to the native one, as shown by gel filtration and limited proteolysis. Reaction of phenylarsinoxide with vicinal dithiols yields products that are much more stable than those with monothiols. Titration of RI with this reagent yielded complete inactivation at a reagent/thiol ratio of 0.5. Taken together, these observations suggest that the thiol groups in RI have a diminished reactivity due to three-dimensional constraints. After the initial modification of a small number of thiol groups, a conformational change occurs which causes an increase in reactivity of the remaining thiols. The thiol groups are situated close enough together to permit the formation of 15 disulfide bridges in the inactive molecule.
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PMID:Inactivation of ribonuclease inhibitor by thiol-disulfide exchange. 144 7

1. A ribonuclease isolated from porcine thyroid cytosol using phenol: sodium dodecylsulfate treatment was associated with RNA and identical to latent alkaline ribonuclease. 2. Distribution of activity between aqueous and phenolic phases depended on pH, RNA, and ribonuclease inhibitor. 3. The ribonuclease was totally resistant to urea, guanidinium: HCl, chloroform:isoamyl alcohol, ethanol, heating at 100 degrees C for 10 min or at 80 degrees C plus 100 mM NaCl. It was highly resistant to hydrolysis by proteinase K except in the presence of detergent. 4. The extreme stability and other properties of latent alkaline ribonuclease could be the result of its association with RNA.
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PMID:Porcine thyroid cytosolic, latent alkaline ribonuclease: resistance to protein denaturants. 149 76

When isolated human fibroblast lysosomes are incubated with 4 microM [32P]phosphate at pH 7.0, orthophosphate is transported into lysosomes and is rapidly incorporated into low and high molecular weight products. We have characterized the high molecular weight (HMW) lysosomal material into which [32P]phosphate is incorporated and have found it to consist of long chains of inorganic polyphosphate based on the following observations. 1) greater than 97% of HMW 32P-lysosomal material is converted to [32P]orthophosphate when incubated with 1 N HCl for 20 min at 100 degrees C. 2) Incubation of HMW 32P-lysosomal material at pH 7.0 and 65 degrees C for 96 h results in the formation of [32P]trimetaphosphate, which is known to be produced only from linear chains of polyphosphate under these conditions. 3) HMW 32P-lysosomal material is resistant to degradation by proteinase K, ribonuclease, and deoxyribonuclease and extracts into the aqueous phase during phenol/chloroform extractions. 4) HMW 32P-lysosomal material displays heterogeneous mobility on polyacrylamide gels with most chains ranging in length from 100 to at least 600 phosphate residues. 5) HMW 32P-lysosomal material is partially hydrolyzed under alkaline conditions to yield a continuous ladder of polyphosphate species differing by one or several residues in length on polyacrylamide gels.
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PMID:Incorporation of [32P]orthophosphate into long chains of inorganic polyphosphate within lysosomes of human fibroblasts. 174 Apr 14


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