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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The circular DNA of hepatitis B Dane particles, which serves as the primer/template for an endogenous DNA polymerase, was analyzed by electrophoresis before and after a polymerase reaction and after digestion by restriction endonuclease or single-strand-specific endonuclease S1. The unreacted molecules extracted from the particles were electrophoretically heterogeneous, and treatment with S1 nuclease produced double-stranded linear DNA ranging in length from 1,700 to 2,800 base pairs (bp). After an endogenous DNA polymerase reaction, two discrete species of DNA molecules were found: a circular form and a linear form 3,200 bp long. The reaction resulted in a population of molecules with an elongated and more homogeneous double-stranded region. These results suggest that the circular molecules in Dane particles have single-stranded regions of varying lengths that are made double stranded during the DNA polymerase reaction. The endogenous DNA polymerase was found to initiate apparently at random in a region spanning more than a third of the molecule. Analysis of restriction endonuclease cleavage fragments of the fully elongated DNA revealed that although the molecules were of a uniform length, they were somewhat heterogeneous in sequence. The sum of the sizes of the 10 major endonuclease Hae III-generated fragments, detected by ethidium bromide, was 3,880 bp. Two additional fragments (B and G) detected by autoradiography after an endogenous DNA polymerase reaction with (32)P-labeled deoxynucleoside triphosphates made the total 4,910 bp.
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PMID:Structure of hepatitis B Dane particle DNA and nature of the endogenous DNA polymerase reaction. 6 27

Hepatitis B virus DNA made fully double stranded by a virion DNA polymerase reaction could be converted from circular to linear molecules by heating in 10 mM NaCl at 77 degrees C or in 100 mM NaCl at 90 degrees C for 15 min. Heat-generated linear hepatitis B virus DNA was reannealed to circular molecules by incubating in higher salt concentrations. The identity of the molecular forms was established by their electrophoretic mobility and appearance in electron micrographs. Recircularization was blocked by reacting linear molecules with nuclease S1 or avian myeloblastosis virus reverse transcriptase. These results suggest that the heated linear DNA had single-stranded ends with complementary nucleotide sequences. It also suggests that a discontinuity or nick is present in each strand of the circular DNA molecule after the single-stranded region is made double stranded by the virion DNA polymerase reaction. The difference in contour length by electron microscopy of circular and linear molecules spread under aqueous conditions suggested that the discontinuities in the two strands were about 270 base pairs apart. The amount of nucleotide incorporated into the ends of heat-generated linear hepatitis B virus DNA by reverse transcriptase suggested that the single-stranded ends were about 305 bases in length. This fully double-stranded linear DNA was cleaved with EcoRI or HpaI restriction endonuclease. The sum of the two fragments generated by each totaled 3,510 base pairs, 310 base pairs greater than the contour length of circular hepatitis B virus DNA which represents a third estimate of the distance between the discontinuities in the two DNA strands of circular DNA. Restriction endonuclease cleavage also indicated that the ends of heated linear DNA which correspond to the discontinuities in the two strands of the circular DNA are at unique sites in the DNA with respect to the restriction sites.
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PMID:Hepatitis B viral DNA molecules have cohesive ends. 9 58

DNA of hepatitis B virus (HBV) of hepatitis B surface antigen (HBsAg) subtype adw2 made fully double stranded by the virion DNA polymerase and radiolabeled either by the virion DNA polymerase reaction or by nick-translation with 32P-labeled deoxynucleoside triphosphates was used to establish a map of restriction endonuclease cleavage sites by the method double and triple enzyme digestion and to determine the relative positions of several unique physical features of this DNA. The five restriction sites for enzyme HincII, the two sites each for BamHI, Ava I, and Bgl II, and the single sites for EcoRI, Pst I, Hpa I, and Taq I were positioned relative to each other. Within this map, the single-stranded region in HBV DNA has been localized and the locations of nicks in each strand (a and b) have been determined with respect to restriction sites on the circular map. Comparison of restriction endonuclease cleavage patterns of DNAs of HBV of HBsAg subtypes adw2, ayw3, and adrq+ revealed consistent differences among subtypes and occasional differences within subtypes.
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PMID:Restriction endonuclease cleavage map and location of unique features of the DNA of hepatitis B virus, subtype adw2. 29 95

DNA extracted from hepatitis B virus Dane particles has been cloned in bacteria using a plasmid vector. A full-length clone has been examined by restriction endonuclease analysis, and the nucleotide sequence of an 892-base pair fragment from cloned hepatitis B viral DNA encoding the surface antigen gene is reported. The amino acid sequence deduced from the DNA indicates that the surface antigens is a protein consisting of 226 amino acids and with a molecular weight of 25,398. The portion of the gene coding for this protein apparently contains no intervening sequences.
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PMID:Nucleotide sequence of the gene coding for the major protein of hepatitis B virus surface antigen. 47 Oct 53

To assess the effects of the combination of persistent hepadnavirus infection and chemical carcinogen exposure, aflatoxin B1 (AFB) was administered p.o. for 60 days to congenitally duck hepatitis B virus (DHBV)-infected and virus-free Pekin ducks, starting at 3 days of age, during a 28-month study. Hepatic neoplasia occurred only in AFB-dosed ducks. Hepatocellular carcinomas or biliary carcinomas occurred in 4 of 8 DHBV-infected and 3 of 4 DHBV-free ducks, and hepatocellular adenomas developed in 2 DHBV-infected AFB-dosed ducks that survived 20 months or longer. Altered foci of hepatocytes similar to those observed in chemical carcinogen-dosed rodents, characterized by enlarged eosinophilic hepatocytes or vacuolated cytoplasm, occurred in AFB-dosed ducks. Cells in foci or hepatic neoplasms did not contain histochemically detectable gamma-glutamyltranspeptidase but were distinguished from uninvolved parenchyma by altered glycogen content. Immunohistochemical staining indicated that DHBV core antigen persisted in liver, spleen, pancreas, and, to a lesser extent, kidney of most congenitally infected ducks up to 28 months of age. Hepatic neoplasms contained only patches of hepatocytes were detectable viral antigen. Southern blot analysis of restriction endonuclease-digested neoplastic and normal liver DNA revealed high molecular weight forms of DHBV DNA consistent with integration of viral DNA into the genome of hepatic neoplasms from 3 of 4 DHBV-infected ducks but not nontumorous liver. These findings indicate that AFB is a potent hepatic carcinogen in ducks and that persistent congenital DHBV infection did not contribute significantly to the emergence of hepatic neoplasia in ducks under these conditions.
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PMID:Hepatic neoplasms in aflatoxin B1-treated, congenital duck hepatitis B virus-infected, and virus-free pekin ducks. 197 46

Authors have successfully established 7 human hepatocellular carcinoma (HCC) cell lines. In one of these cell lines, JHH-7, derived from HBs antigen positive HCC, hepatitis B virus (HBV) genome was analyzed by Southern blot hybridization. Digesting with Hind III restriction endonuclease, two bands were obtained at 6.0 and 2.5 kb, that is the integration of HBV genome was confirmed at the two sites of chromosomes in this cell line. And analyzing with 32P labeled HBV-DNA fragments for probes, it was indicated that integrated HBV genome was incomplete one containing from X to C region.
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PMID:[Analysis for the integrated hepatitis B virus genome in cells of established human hepatocellular carcinoma cell line JHH-7]. 217 76

In order to determine whether integrated hepatitis B virus DNA sequences in primary liver tumours are methylated we have analysed tumour DNA digested with either MspI or HpaII restriction endonuclease by Southern hybridization. Our results demonstrate methylation in 11 of 17 tumour DNA samples. Where possible, we have examined the tumour tissues for expression of HBsAg and HBcAg using the indirect immunoperoxidase technique. One tumour was positive for both HBsAg and HBcAg and a second was positive for HBsAg alone. Both of these tumours were in the group in which methylation of integrated HBV DNA sequences could not be detected. We postulate that methylation of integrated HBV DNA sequences may influence HBV gene expression in hepatocellular carcinoma.
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PMID:Detection of hepatitis B virus DNA in hepatocellular carcinoma: methylation of integrated viral DNA. 283 61

Hepatitis B virus surface antigen (HBsAg) mRNA has been enriched from a hepatoma cell line (PLC/PRF/5) by specific polysome immunoprecipitation and used for cDNA cloning. A HBsAg cDNA clone was identified by in situ hybridization with a cloned viral probe. It was characterized by restriction endonuclease mapping and DNA sequence analysis. Molecular hybridization of PLC/PRF/5 cellular DNA and RNA to [32P]-labeled HBsAg cDNA revealed the integration of at least six copies of the hepatitis B virus (HBV) DNA into the host genome and expression of three DNA species containing HBsAg-specific sequences. The possible role of HBV in the oncogenesis of primary hepatocellular carcinoma is discussed.
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PMID:Molecular cloning and characterization of the cDNA coding for hepatitis B virus surface antigen. 298 65

The entire genome of hepatitis B virus (subtype adr) has been cloned into pBR322. The clones could be classified into at least seven groups by their restriction endonuclease cleavage maps. The nucleotide sequences of the hepatitis B surface antigen (HBsAg)-coding regions for five clones were determined and compared with published sequences of the HBsAg gene including those of adw, ayw, adyw and adr. The 13 available versions of the amino acid sequence of the polypeptide, predicted from the nucleotide sequences, were analysed in terms of the established specificities of the HBsAg, including the four subtypes. The analysis indicated that a relatively hydrophilic region of the HBsAg protein, spanning amino acid residues 110 to 160, specifies the major (w) and (r) subtype system. The (w/r) subtype appears to depend on changes in one or more variable amino acids at positions 47, 110, 113, 126 and 160 of the HBsAg polypeptide.
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PMID:Structural analysis of the gene coding for hepatitis B virus surface antigen and its product. 396 37

Little is known about the replicative forms of hepatitis B virus (HBV) in the liver in chronic liver disease. We therefore analyzed HBV DNA and the changes in DNA signals after endonuclease digestion in liver tissues taken from 64 patients with hepatitis B surface antigen-positive chronic liver disease. The "active" replication pattern, which included various replicative intermediates, was seen in 36 of 38 (95%) hepatitis B e antigen-seropositive patients. This pattern was also found in 5 of 26 (19%) hepatitis B e antigen-seronegative patients who showed the highest mean serum alanine aminotransferase level (403 +/- 184 mU/ml). Most of them had advanced liver disease. Episomal viral DNA of an "inactive" type having only the supercoiled form was found in 3 patients; they showed the lowest mean serum alanine aminotransferase level (27 +/- 7 mU/ml) and only mild liver disease. As with duck HBV infection, episomal replicative forms of human HBV could be resolved by Southern blot analysis and seem to have clinical implications in human HBV infection.
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PMID:Active and inactive replication of hepatitis B virus deoxyribonucleic acid in chronic liver disease. 401 3


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