Search results for "DNA POLYMERASE"
showing 10 items of 83 documents
RNA dependent DNA polymerase in cells of xeroderma pigmentosum
1971
Abstract Cells from X.P. ∗ skin contain an RNA dependent DNA polymerase, while in cells from normal skin this enzyme is lacking. This finding stimulates the thought that carcinogenesis in X.P. cells is due to an infection with an oncogenic RNA virus.
BER, MGMT, and MMR in defense against alkylation-induced genotoxicity and apoptosis
2001
Methylating carcinogens and cytostatic drugs induce different methylation products in DNA. In cells not expressing the repair protein MGMT or expressing it at a low level, O6-methylguanine is the major genotoxic, recombinogenic, and apoptotic lesion. Genotoxicity and apoptosis triggered by O6-methylguanine require mismatch repair (MMR). In cells expressing O6-methylguanine-DNA methyl transferase (MGMT) at a high level or for agents producing low amounts of O6-methylguanine, N-alkylations become the major genotoxic lesions. N-Alkylations are repaired by base excision repair (BER). In mammalian cells, naturally occurring mutants of BER have not been detected, which points to the importance of…
Inhibition of herpesvirus DNA synthesis by 9-beta-D-arabinofuranosyladenine in cellular and cell-free systems.
1977
9-beta-D-Arabinofuranosyladenine 5'-triphosphate (ara-ATP) is an inhibitor both of DNA polymerase-alpha and -beta from noninfected rabbit kidney cells and of the DNA-dependent DNA polymerase induced by herpes simplex virus Type 1 (strain IES). The studies were performed with partially purified enzymes, and each of the different polymerase preparations contained only one DNA-dependent DNA polymerase species. These enzymes were inhibited in a competitive manner. The HSV-induced DNA-dependent DNA polymerase was 39-fold more sensitive to ara-ATP than was cellular DNA polymerase-beta and 116-fold more sensitive than cellular DNA polymerase-alpha. The affinity of the HSV-induced enzyme for ara-AT…
Bleomycin, an Antibiotic That Removes Thymine from Double-Stranded DNA
1977
Publisher Summary This chapter reviews that bleomycins are members of a new class of DNA-modifying agents, the quasi-enzymes. In in vitro systems, bleomycin first removes thymines from native DNA by hydrolysis of the N-glycosidic bonds without modifying the deoxyribose moiety. In a second step, single-strand scissions occur at the sites of the nonglycosidic deoxyribose moieties, resulting in the formation of 3'-OH and 5'-P termini. It is suggested that bleomycin is bound to DNA by interaction of the positively charged terminal amine moiety with the negatively charged phosphate group in DNA; intercalation seems to be involved in binding. Bleomycin is inactivated by copper and zinc ions, prob…
Bleomycin, a selective inhibitor of DNA-dependent DNA polymerase from oncogenic RNA viruses.
1972
Abstract Bleomycin, an antibiotic, inhibits the DNA-dependent DNA polymerase from Rauscher murine leukemia virus. Higher concentrations of BLM ∗ are required to inhibit it's RNA-dependent DNA polymerase. These inhibition effects of the non-competitive type are not altered by preincubation of the DNA with BLM. Under comparable conditions neither the DNA-dependent DNA polymerase activity from E. coli and mouse liver nor the DNA-dependent RNA polymerase activity from mouse lymphoma cells are affected by BLM.
Activity and kinetics of DNA dependent DNA and RNA polymerases n xeroderma pigmentosum and in normal human skin.
1971
1. DNA dependent DNA polymerase (E.C.2.7.7.7) was prepared from human normal and from Xeroderma pigmentosum skin. 2. DNA polymerase from normal skin has the same Michaelis constant with native and denatured DNA as templateKm= 120 ± 11 µg DNA/ml, with differing maximum reaction velocities. 3. The enzyme from Xeroderma pigmentosum has the same Michaelis constant for denatured DNA as the enzyme from normal skin, but with native DNA as template, theKmvalue is lower (97.2 ± 9.8). The maximum reaction velocities of the Xeroderma pigmentosum enzyme with native resp. denatured DNA as template are the same. 4. DNA dependent RNA polymerases (E.C.2.7.7.6) from normal and Xeroderma pigmentosum skin wer…
Synthesis of nucleoside and nucleotide conjugates of bile acids, and polymerase construction of bile acid-functionalized DNA.
2010
Aqueous Sonogashira cross-coupling reactions of 5-iodopyrimidine or 7-iodo-7-deazaadenine nucleosides with bile acid-derived terminal acetylenes linked via an ester or amide tether gave the corresponding bile acid–nucleoside conjugates. Analogous reactions of halogenated nucleoside triphosphates gave directly bile acid-modified dNTPs. Enzymatic incorporation of these modified nucleotides to DNA was successfully performed using Phusion polymerase for primer extension. One of the dNTPs (dCTP bearing cholic acid) was also efficient for PCR amplification.
Alterations of DNA-dependent DNA polymerase activities in the immature quail oviduct in response to estrogen stimulation.
1975
Administration of diethylstilbestrol, an estrogen analogue, to immature female quails causes an increase of extractable DNA-dependent DNA polymerase activities from the oviduct. At least two forms of polymerases have been determined, a high molecular weight polymerase (210,000 daltons) and a low molecular weight polymerase (34,000 daltons) calculated from column chromatography Sephadex G-200. During the primary hormone stimulation the amount of extractable enzyme reaches a maximum on the fifth day after daily injections of the hormone. In the period of withdrawal the activities decrease and reach values similar to those determined in the unstimulated oviducts. During secondary stimulation t…
DNA-dependent DNA polymerase pattern in noninfected and herpesvirus infected rabbit kidney cells.
1973
In this paper we report on a DNA-dependent DNA polymerase produced in herpesvirus infected cells which is not present in virions. It differs from the polymerases of noninfected cells by its molecular weight as well as by its insensitivity to cytosine arabinoside triphosphate (ara-CTP).
Biochemical Aspects of Chick Embryo Retina Development: The Effects of Glucocorticoids
1989
In chick embryo retina during development, DNA synthesis and the activities of DNA polymerase, thymidine kinase, thymidylate synthetase, and ornithine decarboxylase (ODC) declined in parallel from day 7 to 12. The administration in ovo of hydrocortisone reduced significantly, particularly at 8-10 days of incubation, both DNA synthesis and the four enzyme activities tested. The effect was dose dependent, reaching the maximum with 50-100 nmol of hydrocortisone, 8-16 h after treatment. The highest inhibition was found for ODC activity (70%), followed by thymidine kinase activity (62%) and DNA synthesis (45%), whereas activities of DNA polymerase and thymidylate synthetase were reduced only by …