Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Crossed immunoelectrophoresis of Triton X-100-solubilized plasma membranes of Micrococcus lysodeikticus established the presence of 27 discrete antigens. Individual antigens were identified as membrane components possessing enzyme activity by zymogram staining procedures and by reactivity of certain antigens with a selection of four lectins in the crossed-immunoelectrophoresis (immunoaffinoelectrophoresis) system. Absorption experiments with intact, stable protoplasts and isolated membranes established the asymmetric nature of the M. lysodeikticus plasma membranes. Of the 14 antigens with determinants accessible solely on the cytoplasmic face of the membrane, four possessed individual dehydrogenase activities, and a fifth was identifiable as a component possessing adenosine triphosphatase (EC 3.6.1.3) activity. Evidence from absorption studies with isolated membranes suggested that antigens such as the adenosine triphosphatase complex were more readily accessible to reaction with antibodies than was succinate dehydrogenase (EC 1.3.99.1), for example. Twelve antigens were located on the protoplast surface as determined by antibody absorption, and the succinylated lipomannan was identified as a major antigen. At least five other antigens possessed sugar residues that interacted with concanavalin A. With the antisera generated to isolated membranes, there was no evidence suggesting that any of these antigens was not detectable on either surface of the plasma membrane. From absorption experiments with washed, whole cells of M. lysodeikticus, it was concluded that the immunogens on the protoplast surface were also detectable on the surface of the intact cell. However, some of the components such as the succinylated lipomannan appeared to be exposed to a greater extent than others. The cytoplasmic fraction from M. lysodeikticus was used as an antigen source to generate antibodies, and 97 immunoprecipitates were resolvable by crossed immunoelectrophoresis. In the cytoplasm-anticytoplasm reference immunoelectrophoresis pattern of precipitates, three of the immunoprecipitates unique to the cytoplasmic fraction were identifiable by zymogram staining procedures as catalase (EC 1.11.1.6), isocitrate dehydrogenase (EC 1.1.1.42), and polynucleotide phosphorylase (EC 2.3.7.8). The identification of membrane and cytoplasmic antigens (including the above-mentioned enzymes) provides a sensitive analytical system for monitoring cross-contamination and antigen distribution in cellular fractions.
J Bacteriol 1977 Dec
PMID:Membrane asymmetry and expression of cell surface antigens of Micrococcus lysodeikticus established by crossed immunoelectrophoresis. 14 22

The antigenic composition and molecular structure of the plasma membrane of Streptococcus pyogenes (group A; M type 6) were studied by crossed immunoelectrophoresis (XIE) and other related quantitative immunoelectrophoretic techniques. After establishment of a reference pattern of 29 immunoprecipitates, the relative differences in amounts of individual antigens contained in membranes isolated from cells that were harvested during the exponential or stationary phase of growth were examined. Relative increases and decreases in amounts of individual antigens were estimated from the areas subtended by immunoprecipitates after XIE of Triton X-100 extracts. The asymmetric distribution of antigens on the inner and outer surfaces of the membrane was established in absorption experiments with intact, stable protoplasts. Of the 29 immunoprecipitates, 8 appeared to contain antigens exposed on the outer surface of the membrane, whereas 11 appeared to contain antigens either located on the inner surface or unexposed. Six antigens appeared to have limited exposure on the outer surface, and four others remain to be assigned. Certain immunoprecipitates were characterized with respect to enzymatic activity or interaction with the lectin concanavalin A. Reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3), adenosine triphosphatase (EC 3.6.1.3), and polynucleotide phosphorylase (EC 2.3.7.8) were demonstrated by zymogram techniques. The latter two activities were present within the same immunoprecipitate, suggesting the occurrence of a multienzyme complex. In addition, the areas under the immunoprecipitates containing the three enzymatic activities were not affected by absorption of antimembrane immunoglobulin with intact protoplasts and thus appeared to be located on the inner surface of the membrane. The results from absorption experiments also suggested that the exposure of outer protoplast surface antigens was greater on protoplasts from exponential-phase cells than on those from stationary-phase cells, even when found in increased amounts in the latter.
Infect Immun 1979 Dec
PMID:Quantitative immunoelectrophoretic analysis of Streptococcus pyogenes membrane. 16 Aug 91

Specific activity and level of polynucleotide phosphorylase (PNPase) in polyribosomes of regenerating liver of adult rats, liver of newborn rats and in malignant tumours of rat (sarcoma M-1 and hepatoma 27) were studied. 24 hours after partial hepatectomy the specific activity and level of PNPase in regenerating liver decreased 3--4 times in the fraction of polyribosomes, bound to the endoplasmic reticulum membranes, and remained at a constantly low level in the fraction of free polyribosomes. The PNPase activity also showed a sharp decrease in the fraction of membrane-bound polyribosomes from newborn rats liver and could not be detected either in free or in bound polyribosomes from sarcoma M-1 or hepatoma 27. The PNPase activity in the fraction of bound polyribosomes increased with a decrease in the rate of liver growth (regenerating liver and newborn rats liver), and reached the level normal for adult animals. Possible mechanisms of regulation of the PNPase activity in animal tissue were studied. It was found that a 2-fold administration of cyclic 3,5'-AMP to intact animals (5 mg per 100 g of body weight) with an interval of 8 hours, corresponding to the interval between two peaks of the increase in cyclic 3,5'-AMP concentration following partial hepatectomy, diminished the PNPase specific activity in polyribosomes by 30%. A factor, presumably of protein origin, which induced a release of PNPase from polyribosomes of normal rat liver but did not affect the activity of the liberated enzyme, was detected in the cell sap of sarcoma M-1 and hepatoma 27.
Biokhimiia 1976 Dec
PMID:[The activity of polynucleotide phosphorylase in polyribosomes of regenerating liver of adult rats, liver of newborn rats and in some reinoculated tumours]. 19 Nov 6

Poly (2'-chloro-2'-deoxyadenylic acid) and poly (2'-bromo-2'-deoxyadenylic acid) were synthesized from the corresponding diphosphates with the aid of polynucleotide phosphorylase from E. coli. UV, CD, acid titration and mixing with poly (U) were investigated. Comparing these properties with those of poly (A) and poly (2'-azido-2'-deoxyadenylic acid), it was found that 2''substituents exert significant effects on the thermal stability of these polynucleotides, though the overall conformational structure was not greatly changed.
Nucleic Acids Res 1977 Dec
PMID:Polynucleotides. L. Synthesis and properties of poly (2'-chloro-2'-deoxyadenylic acid) and poly (2'-bromo-2'-deoxyadenylic acid). 34 Oct 84

Replication of RNA bacteriophages in the presence of rifamycin was studied in different Escherichia coli strains that vary in RNase content but are not isogenic: AB259 RNase+, Q13 RNase I- PNPase-, AB105 RNase I- RNase III-. It was found that rifamycin did not affect characteristics of phage replication such as the general pattern of viral RNA synthesis and intracellular development of the phage. These characteristics are strain specific and independent of the cell growth rate, which defines only phage release. The inhibition of cell division by rifamycin interfered with the release of the phage and thus produced an apparent effect of rifamycin on phage replication.
J Virol 1978 Dec
PMID:Replication of RNA bacteriophages in the presence of rifamycin. 36 77

RNAase which usually contaminates commercial pancreatic DNAase preparations can be removed by affinity chromatography on agarose-coupled anti-RNAase antibodies. RNA treated with purified DNAase can be re-isolated intact, as determined by polyacrylamide gel electrophoresis under denaturing conditions. This method might be applicable to purification of other preparations which are used in RNA research, such as PNPase (polynucleotide phosphorylase) and specific antibodies for polysome immunoprecipitation. The non-specific binding of DNAase in our system is less than 5% and the loss of specific activity of DNAase I is less than 1%.
J Biochem Biophys Methods 1979 Dec
PMID:A simple method for elimination of RNAase contamination from DNAase preparations. 55 95

According to Cleland's theoretical predictions, inosine phosphorolysis catalyzed by chicken and pigeon's liver PNPase (Purine nucleoside:ortophosphate ribosyltransferase. E.C. 2.4.2.1.) appears to be a rapid equilibrium random bi-bi with "dead end" enzyme-phosphate-hypoxantine complex. This mechanism implies the existence of two essential active centers in the enzymatic molecule to which inosine and phosphate attach themselves independently. The observed lack of analogy in the PNPase mechanism of mechanism of different species seems to suggest the existence of structural differences between them.
Rev Esp Fisiol 1975 Dec
PMID:[Purine nucleoside phosphorylase. Catalytic reaction mechanism. II. Product-reaction-inhibition (author's transl)]. 81 90

It has been reported earlier that phage Qbeta RNA (Gilvarg, C., Bollum, F.J. and Weissmann, C. (1975) Proc. Natl. Acad. Sci. U.S. 72, 428-432) elongated at its 3' terminus with up to 100 or more AMP residues retained its full infectivity for Escherichia coli spheroplasts, and that the resulting progeny did not inherit the poly (A) appendage. We now show that while poly (A)-Qbeta RNA appears to function normally as messenger for the synthesis of virus-specific proteins it has lost its capacity to serve as template for Qbeta replicase. Template function could be restored by phosphorolysis with polynucleotide phosphorylase. Taken in conjunction, these results imply that after poly (A)-Qbeta RNA enters the spheroplast a host enzyme (perhaps polynucleotide phosphorylase) removes part or all of the adenylate residues prior to replication of the RNA.
Biochim Biophys Acta 1975 Dec 19
PMID:Evidence for the participation of a host enzyme in the activation of poly (A)-Qbeta RNA as an infectious agent. 110 68

We have characterized a chloroplast processing activity that catalyzes the conversion of the plastid cytochrome b6/f subunit IV (pet D) mRNA 3' end precursor to the mature RNA possessing a 3' inverted repeat (IR). In a chloroplast soluble protein extract, the activity requires Mg2+ or Mn2+, but not K+. In the absence of Mg2+, the pet D 3' IR-RNA product does not accumulate, and UV-cross-linking indicates that the 3' IR-RNA precursor binds several new proteins in addition to those previously characterized as part of the 3' IR-RNA: protein complex in vitro. In contrast, high concentrations of Zn2+ or Cu2+ suppress protein binding and inhibit the processing reaction. The purified exoribonuclease polynucleotide phosphorylase (E.C.2.7.7.8) is not efficient in processing the pet D 3' IR-RNA precursor, whereas Escherichia coli ribonuclease II rapidly processes the pet D IR-RNA precursor to a product of a size similar to that of the mature 3' IR-RNA, but also rapidly degrades the mature RNA in the absence of chloroplast extract. We therefore conclude that the maturation of the pet D mRNA in vitro requires specific chloroplast enzymes which process the mRNA 3' end precursor in the absence of efficient transcription termination. The chloroplast enzyme activities are biochemically distinct from their bacterial counterparts. We also note that specific chloroplast components may be required to stabilize the mature pet D mRNA 3' end against further exonucleolytic degradation.
Plant Mol Biol 1989 Dec
PMID:Chloroplast mRNA 3' end maturation is biochemically distinct from prokaryotic mRNA processing. 248 89

As a first step to approach the structural and functional analysis of DNA-dependent RNA polymerase II (EC 2.7.7.8), we have isolated genomic sequences for the large subunit of the human enzyme. The sequences homologous to Drosophila RNA polymerase II large subunit sequences are present in the genome as single copy genes, when assayed at high stringency. The polypeptide information is encoded in a mRNA of 7.35 kilobases, as determined by Northern blot analysis. In vitro translation reveals a polypeptide of 220 kDa, similar in electrophoretic mobility to the largest subunit of the enzyme. A fusion-polypeptide synthesized in bacteria contains a region that cross-reacts with anti-RNA polymerase II antiserum. Antiserum directed against the purified fusion protein reacts with the large subunit of RNA polymerase II, whether in the intact IIA (220 kDa) or in the degraded IIB (180 kDa) forms. Moreover, the antifusion protein antibody inhibits not only the purified calf thymus RNA polymerase II activity but also specific RNA polymerase II transcription in a HeLa cell extract. Thus, the DNA fragment isolated contains structural and functional domains of the human RNA polymerase II large subunit.
J Biol Chem 1985 Dec 05
PMID:The gene encoding the large subunit of human RNA polymerase II. 299 7


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