Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The RNase hydrolysis of random-coil (alkaline form) poly A follows biphasic kinetics at low salt concentrations. However, its resistance to RNase increases with the ionic strength. Helical (acidic form) poly A is alos susceptible to RNase but its hydrolysis follows first-order kinetics, and its resistance increases as the pH is lowered. These conformation-dependent kinetics of poly A hydrolysis are similar to those obtained in the hydrolysis of cellular RNA and reovirus double-stranded RNA.
 ...
PMID:The kinetics of pancreatic ribonuclease reaction with alkaline and acidic forms of poly A. 24 30

The stimulatory mechanism of RNA synthesis of calf-thymus chromatin by nuclear 4.5 S RNA from the homologous tissue was investigated by using exogenously added Escherichia coli RNA polymerase. The RNA synthesis was initiated at low concentration of salt, and then the chain elongation was achieved at high concentration of ammonium sulfate in the presence of polyvinyl sulfate. Under these conditions the number of binding sites of RNA polymerase on chromatin which were capable of initiating RNA chain was increased by the addition of the 4.5 S RNA. This stimulation was presumed to result from the release of template restriction in chromatin. The polyvinyl salt minimized ribonuclease activity without changing the RNA polymerase activity bound to the template. Neither rearrangement nor release of chromatin proteins affected the amount or size of RNA produced. Preliminary analysis suggested that the molecular species of RNA produced upon the addition of the 4.5 S RNA from various tissues seemed to be heterologous.
 ...
PMID:Release of template restriction in chromatin by nuclear 4.5s RNA. 32 18

A method for the rapid manual isolation of polytene chromosomes and nuclear membranes from salivary glands of Chironomus tentans is presented and the analysis of some of their RNA and protein components before and after treatment with 2 M salt solutions is summarized.--After salt-incubation the chromosomes still display a considerable number of bands which stain with ethidium bromide and which are sensitive to treatment with DNase, RNase, trypsin, and proteinase K, to a lesser extent with pronase and papain. Analysis of the iodinated residual proteins on SDS gels yield three major and two minor bands (MW between 50,000 and 70,000 dalton) which were also shown to be present in interphase chromosomes of Ehrlich ascites cells which had been treated similarly and are also tightly bound constituents of DNA prepared according to Gross-Bellard et al. (1973). This result indicates the existence of a general class of non-histone proteins involved in keeping the DNA in a supercoiled state. Furthermore their presence in salt-treated nuclear membranes of Chironomus salivary gland cells (and Xenopus oocytes, unpubl.) will be of interest with respect to functional aspects of the nuclear matrix.
 ...
PMID:Effect of salt-treatment on manually isolated polytene chromosomes from Chironomus tentans. 35 13

Two ribonuclease H activities have been found in yeast RNA polymerase A. The nuclease activities comigrated with subunits A49 (Mr = 49,000) and A40 (Mr = 40,000), after electrophoresis in a sodium dodecyl sulfate polyacrylamide gel containing [32P](rG)n . (dC)n as substrate. Both activities were also found, among other nucleases, in a high salt chromatin extract. Several lines of evidence suggest that the chromatin RNase H of 49,000 daltons (RNase H49) is the same protein as subunit A49. They co-migrate on sodium dodecyl sulfate-gel electrophoresis, have the same chromatographic properties, and dissociate simultaneously from RNA polymerase A. Fractions containing RNase H49 stimulate RNA synthesis by RNA polymerase A* lacking A49 and A34.5 subunits. Finally, limited proteolysis of the protein band having RNase H49 activity yields the characteristic fingerprint of the A49 subunit. This subunit, therefore, exists in two states: bound to chromatin and associated with RNA polymerase A. On the other hand, it is not yet clear whether the RNase H activity of 40,000 daltons, associated with RNA polymerase A, is due to the A40 subunit or whether it represents a trace contamination by a very active nuclease tightly bound to the enzyme.
 ...
PMID:Identification of two different RNase H activities associated with yeast RNA polymerase A. 38 60

Nucleoli of both chick embryos and mouse Ehrlich ascites cells contain an enzymatic activity that is very similar to RNase DII, an enzyme isolated from total chick embryos for its ability to degrade double-stranded RNA. The enzyme can be extracted by low salt/EDTA from nucleoli and is associated with pre-ribosomal 80-S and 55-S particles. Under ionic conditions which are inhibitory for the nucleolytic activity the transcript in vitro of nucleoli is not processed and sediments around 45 S. Under salt conditions which are optimal for the nucleolar enzyme the nucleolar transcripts are cleaved to distinct intermediate-sized molecules. Addition of the chicken RNase DII or RNase III to the nucleolar transcription system results in a similar shift of the chain length of the RNA molecules. It is concluded that a nucleolar RNase recognizing double-stranded regions in the pre-ribosomal RNA is involved in the maturation of ribosomal RNA.
 ...
PMID:Localisation of an endonuclease specific for double-stranded RNA within the nucleolus and its implication in processing ribosomal transcripts. 42 96

Twenty Syrian golden hamsters recieved weekly injections of pancreatic cancer inducing DHPN. Their Poly (U) specific serum RNase levels were significantly elevated when compared to the control levels. Following salt fractionation, Poly (U) specific activity was present in both the 40% and 50% salt saturated fractions. Tissue assays showed that Poly (U) specific RNase was present in both pancreas and liver tissue extract, although the liver tissue RNase had a different pH maximum than that of the serum RNase.
 ...
PMID:RNase levels in golden hamster with DHPN induced pancreatic cancer. 44 89

The aim of our work was to evaluate the diagnostic value of the determination of the ribonuclease activity in sera of patients with gynaecologic malignomas. We therefore developed an assay for ribonuclease activity. In the course of optimization of the assay conditions we investigated the applicability of 4 commercially available RNA-preparations as substrate and the dependency of the ribonuclease activity on salt-concentration. The ribonuclease activity of 42 representative female patients (12 controls, 11 with ovarian carcinoma, 10 with corpus carcinoma, 9 with collum carcinoma) is presented.
 ...
PMID:[Serum ribonuclease activity in patients with gynaecologic malignomas (author's transl)]. 51 Aug 96

Semi-thin and ultrathin sections of locust testes have been incubated in 3H-actinomycin D solution and submitted to radioautography. The improved technical conditions described allow the reproducible obtainment of cell radioautographs with a moderate nuclear labelling and a very low nonspecific background which are usable for semi-quantitative results. Extraction with enzymes (DNase, RNase, pronase) or concentrated salt solution have been carried out before 3H-Actinomycin D treatment in order to characterize the reaction. The semi-quantitative results obtained at the light microscope level suggest that, in relation to the structural and chemical changes which occur in chromatin during spermiogenesis, some proteins may be easily hydrolysed in early spermatids. In ultrathin sections of spermatocytes the X chromosome is heavily "stained" with 3H-Actinomycin D, while 3H-uridine is not incorporated into the sex chromatin. These results are discussed in the light of current ideas on the constitution of active chromatin.
 ...
PMID:3H-actinomycin D binding to ultrathin section of plastic-embedded Locusta migratoria testicular tubules. Improvement of the technique and further characterization of the reaction. 52 Mar 26

Nuclear RNP from Triturus oocytes is organized as strings of beads which can be converted into 20-nm-diameter monoparticles with mild RNase treatment or into 5-nm-thick linear fibrils with low salt treatment. The protein component comprises a heterogeneous size-range of polypeptides which differ from the polypeptides of the other nucleoproteins of oocytes. The RNA is of high molecular weight, sediments mostly in excess of 50 S, and is capable of assuming considerable secondary structure. Duplex regions in the form of hairpin loops are present and may serve as focal points in the condensation of the RNP transcript fibres to generate the periodic beaded structure. The structure of the beads may be maintained by means of protein-protein interaction since at salt concentrations between 1 and 2 M NaC1 all of the proteins are released in a cooperative manner as various sized aggregates which sediment at 15-30 s. There are no specific proteins obviously peculiar to either the beaded or the fibrillar RNP configuration. The various properties of nuclear RNP are compared with those of chromatin.
 ...
PMID:The structure of nuclear ribonucleoprotein of amphibian oocytes. 56 Oct 88

The trimerization constants of glucagon at pH 10.6 in 0.76 M K2HPO4 have been calculated from circular dichroism data between 5 and 50 degrees C. The free energy, enthalpy, and entropy of transfer have been evaluated from the current results and published data in 0.20 M phosphate. The free energies of transfer are derived completely from an increase in the entropy of transfer, since the enthalpy of transfer is less favorable at all temperatures. These parameters are compared with those of various model groups and compounds: CH2, peptide, methane, ethane, and the 1--13 N-terminal fragments of ribonuclease. The effects of fluoride and chloride on the self-association of glucagon have been compared with that of phosphate at 25 degrees C. These effects are consistent with the binding of approximately one molecule of salt to the trimer and a systematic decrease in the number of water molecules bound to the trimer compared to the monomer for the series K2HPO4, KF, and KCl.
 ...
PMID:Effects of Hofmeister salts on the self-association of glucagon. 64 94


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>