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

---

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

Using purified single-stranded ovalbumin complementary DNA (cDNAov) as a template for avian myeloblastosis (AM) virus reverse transcriptase, we have enzymatically synthesized a complete double-stranded cDNAov sequence. Our data suggests that many single-stranded cDNAov molecules contain short double-stranded sequences (hairpins) at their 3' termini capable of acting as primers for synthesis of complete double-stranded cDNAs. Optimum conditions for synthesis of the double-stranded cDNAov were found to be a high temperature (46 degrees) and a low salt concentration. Nevertheless, in all cases 40% of the initial single-stranded cDNAov molecules fail to prime for synthesis of a complementary double strand. Following synthesis, the second DNA strand is covalently linked to the first cDNAov strand as shown by analysis on alkaline sucrose gradients. The two strands have a high Tm on hydroxylapatite (89 degrees). These intact double-stranded cDNAov structures have a bouyant density in CsCl gradients of 1.700 g/cm3 and rapidly renature after heat denaturation with a C0t1/2 value of less than 2 X 10(-6) mol s liter(-1). All size classes of cDNAs, i.e. partial as well as complete transcripts of the mRNA, are capable of forming double-stranded structures. The closed loop of the double-stranded cDNAov could be opened with S1 nuclease. The denatured complementary strands of the cDNAov then renatured with the appropriate second order kinetics at a C0t1/2 value of 1.89 X 10(-3) mol s liter(-1). Using the enzyme terminal deoxyribonucleotidyltransferase to label to free 3'-terminal end of double-stranded [32P]cDNAov with 3H, we demonstrate a convenient procedure to study the site for restriction endonuclease cleavage within the ovalbumin gene.
...
PMID:The ovalbumin gene. In vitro enzymatic synthesis and characterization. 6 59

Details are presented of the in vitro synthesis of double-stranded DNA complementary to purified Xenopus globin messenger RNA, using a combination of reverse transcriptase, fragment 'A' of E. coli DNA polymerase 1 and S1 endonuclease. After selection of duplex DNA molecules approaching the length of Xenopus globin messenger RNA by sedimentation of the DNA through neutral sucrose gradients, the 3'-OH termini of the synthetic globin gene sequences were extended with short tracts of oligo dGMP using terminal transferase. This material was integrated into oligo dCMP-extended linear pCR1 plasmid DNA and amplified by transfection of E. coli. Plasmids carrying globin sequences were identified by hybridization of 32P-labelled globin mRNA to total cellular DNA in situ, by hybridization of purified plasmids to globin cDNA in solution, by analysis of recombinant DNA on polyacrylamide and agarose gels, and by heteroduplex mapping. The results show that extensive DNA copies of Xenopus globin mRNA have been integrated into recombinant plasmids.
...
PMID:Recombinant plasmids containing Xenopus laevis globin structural genes derived from complementary DNA. 34 4

Terminal deoxynucleotidyltransferase is an enzyme which has been found to be associated with thymus cells, bone marrow cells, as well as leukocytes from patients with acute lymphoblastic leukemia and chronic myelocytic leukemia in blast crisis. We report here the purification of terminal deoxynucleotidyltransferase by an oligonucleotide affinity (oligo(dT)12-18 cellulose) column. By using a 35 to 70% (NH4)2SO4 cut, Sephacryl S200 column and an oligo(dT) cellulose column, terminal deoxynucleotidyltransferase has been purified from calf thymus cells to a specific activity of more than 8,500 units/mg of protein. The terminal deoxynucleotidyltransferase purified by this method contains no detectable DNA-dependent DNA polymerase or endonuclease activities. Furthermore, sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the enzyme appears to be homogeneous, with two polypeptides corresponding to the two subunits alpha (10,000) and beta (23,000) of terminal deoxynucleotidyltransferase. These data indicate that oligo(dT)12-18 cellulose can be used as a rapid and selective affinity column for the purification of terminal deoxynucleotidyltransferase.
...
PMID:Purification of terminal deoxynucleotidyltransferase by oligonucleotide affinity chromatography. 64 3

A procedure enabling the highly sensitive detection of accessible restriction endonuclease sites on metaphase chromosomes is described. The procedure is based on the following: (i) a terminal deoxynucleotidyltransferase is used to add a biotinylated nucleotide (Bio-11-dUTP) tail to the 3' hydroxyl terminus generated by the action of a restriction enzyme and (ii) the biotinylated oligonucleotide is detected by a peroxidase-based immunocytochemical method. When used with the 5-methylcytosine-sensitive enzyme Hha I, it gives rise to a pattern close to R and T banding on autosomes. In addition, the staining of one X chromosome in females appears very unusual by its pattern and its strong intensity. This procedure, as applied on a case with a polysomy X chromosome, provides direct evidence of an overall hypomethylation of the inactive X chromosomes.
...
PMID:Inactive X chromosome has the highest concentration of unmethylated Hha I sites. 326 75

Human thyroglobulin mRNA was isolated from Graves' goitres by size selection of total poly(A)-rich RNA in a sucrose gradient. It sedimented at 33 S, as in other mammalian species, and showed a single component of approximately 8500 bases by gel electrophoresis. cDNA was synthesized from the 33-S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor and in conditions allowing the formation of long transcripts. The latter was made double-stranded using reverse transcriptase and blunt-ended with nuclease S1. After tailing with dCTP and terminal transferase, the double-stranded cDNA was annealed to pBR322 DNA that had been cleaved at the endonuclease PstI site and tailed with dGTP. The resulting plasmids were used to transform Escherichia coli C600 cells and four cloned recombinants were selected. Each plasmid DNA was shown to contain a sequence complementary to human thyroglobulin mRNA by hybridization with a labeled 33-S mRNA, visualization of cDNA . mRNA hybrids by electron microscopy and filter hybridization selection of mRNA directing the synthesis of immunologically related thyroglobulin peptides in the reticulocyte lysate. The four inserted DNA sequences were 1400 - 1800 base pairs long, two of them showing an homologous sequence of 1100 base pairs. Together, the four cloned DNA fragments represented 63% of the 8500 bases of human thyroglobulin mRNA.
...
PMID:Cloning of four DNA fragments complementary to human thyroglobulin messenger RNA. 617 25

An endonuclease which introduces single nicks in superhelical DNA co-purifies with the enzyme, terminal deoxynucleotidyl transferase. This activity is found in all homogeneous preparations of terminal transferase tested, and remains associated with the polymerase activity during additional fractionation methods. Kinetic data suggest that the nuclease and polymerase occupy distinct active sites, although multifunctionality has not been proven. However, the ability of the polymerase to synthesize oligodeoxynucleotide products on endonuclease-generated singly-nicked circular duplex DNA may represent an important biological function or signal in lymphoid cells.
...
PMID:A specific endonuclease which co-purifies with calf thymus terminal deoxynucleotidyl transferase. 662 29

Terminal transferase is used to add a single fluorescently labeled dideoxynucleotide to double-stranded DNA prepared by restriction endonuclease action on a bacteriophage. The product is separated by capillary electrophoresis with both hydroxypropylmethylcellulose and non-cross-linked polyacrylamide. The reaction products generate single peaks for each fragment with hydroxypropylmethylcellulose. However, the higher resolution separation produced by non-cross-linked polyacrylamide shows that the product contains two components for each restriction digest fragment. This labeling technique should be useful in restriction fragment length polymorphism studies.
...
PMID:Labeling of double-stranded DNA by ROX-dideoxycytosine triphosphate using terminal deoxynucleotidyl transferase and separation by capillary electrophoresis. 784 33

TrwC is required for conjugal DNA transfer of the broad host range plasmid R388. The purified protein shows in vitro DNA helicase activity. Here we report that it also has in vitro oriT-endonuclease activity. TrwC specifically nicks oriT-containing supercoiled plasmid DNA in the presence of Mg2+, and the nicked DNA can be visualized after treatment with SDS. Sequencing of the nicked DNA showed a specific interruption of the lower DNA strand on the R388 oriT sequence. Both the 5' and the 3' ends of the nick were mapped. The 5' end was not accesible to phosphorylation by T4 polynucleotyde kinase, suggesting a covalent association with TrwC. Analysis of a collection of deletions in oriT indicated that the nucleotide sequences immediately surrounding the nic site are important, but not the only essential feature, for the nicking reaction. Comparison of the R388 nic site with previously published nic DNA sequences suggests that IncF, IncN and IncW plasmids form a family of related nic sites. During the course of this work we have also demonstrated a terminal transferase activity of Sequenase Version 2.0 DNA polymerase, as yet undocumented, which could account for some discrepancies in previously mapped nic sites in other systems.
...
PMID:Nicking activity of TrwC directed against the origin of transfer of the IncW plasmid R388. 785 4

DNA strand breaks which occur in HL-60 cells as a result of activation of endonuclease during apoptosis induced by cell treatment with the DNA topoisomerase I inhibitor camptothecin and topoisomerase II inhibitors teniposide, 4'-(9-acridinylamino)-3-methanesulfon-m-anisidide, and fostriecin were labeled in situ, in individual fixed and permeabilized cells, with biotinylated dUTP (detected by fluoresceinated avidin), using the terminal deoxynucleotidyl transferase or nick translation assays. During the early stage of apoptosis, prior to nuclear fragmentation, the breaks were predominantly localized at the nuclear periphery, close to the nuclear envelope. In more advanced stages, all cellular DNA, then localized within the cell as dense, homogeneous granules of a variety of sizes, was strongly labeled, indicating extensive and more uniform distribution of breaks throughout genomic DNA. Bivariate analysis of the incorporated biotinylated dUTP and cellular DNA content by flow cytometry made it possible to estimate the kinetics of the labeling reaction and relate DNA breaks to cell position in the cycle. The kinetics of biotinylated dUTP incorporation was faster, and the distinction of cells with DNA breaks was more pronounced, using the terminal transferase rather than the nick translation assay. Camptothecin, teniposide, and 4'-(9-acridinylamino)-3-methanesulfon-m-anisidide induced DNA breaks preferentially in S-phase cells, having little effect on cells in the G1 phase of the cycle. In contrast, fostriecin affected cells indiscriminately, in all phases of the cell cycle. The method of detection of DNA strand breaks (3'-hydroxyl termini) in individual cells offers several advantages and can be applied to clinical material (tumor biopsies) to study the induction of apoptosis in tumors during treatment, as a possible prognostic marker. The protein-associated DNA breaks in the "cleavable" DNA-topoisomerase complexes, which are the primary lesions induced by the inhibitors and precede apoptosis, were not detectable by the present methods.
...
PMID:Detection of DNA strand breaks in individual apoptotic cells by the in situ terminal deoxynucleotidyl transferase and nick translation assays. 846 13

Ameloblasts responsible for tooth enamel formation are classified into two different phases: secretion and maturation. At the transition between these secretion and maturation stages, a considerable number of cells die. In this study, we examined the morphology of degenerating ameloblasts by conventional electron microscopy, and DNA cleavage in degenerating ameloblast nuclei by the in situ terminal transferase assay. The results suggest that apoptosis (programmed cell death) in ameloblasts, including DNA ligation is induced at the transitional stage. The nuclear fragments, chromatin condensation and DNA relocation in apoptotic nuclei were examined quantitatively by post-embedding anti-DNA immunogold electron microscopy and the in situ terminal transferase assay combined with electron microscopy. Numerical analysis revealed that immunogold labeling density in the condensed chromatin of apoptotic nuclei was comparable on the average to that in the perinuclear heterochromatin of normal nuclei, and that individual apoptotic nuclear fragments exhibited highly variable to that of normal heterochromatin, to fragments with densities twice as high as that of normal heterochromatin. The in situ terminal transferase assay combined with electron microscopy detected DNA ends exposed by ultrathin sectioning as well as DNA cleavage by a putative endonuclease. In conclusion, the state of the DNA, including its ligation and degeneration, changes gradually during chromatin condensation and nuclear fragmentation of apoptosis.
...
PMID:DNA localization in nuclear fragments of apoptotic ameloblasts using anti-DNA immunoelectron microscopy: programmed cell death of ameloblasts. 853 72


1 2 3 Next >>

---