Search results for "cytosine"

Hydroxyl Radical Addition to Thymine and Cytosine and Photochemistry of the Adducts at the C6 Position

2019

Cyclobutane Pyrimidine Photodimerization of DNA/RNA Nucleobases in the Triplet State

2010

The photoinduced formation of cyclobutane pyrimidine dimers in the triplet excited state of the DNA/RNA pyrimidine nucleobases pairs has been studied at the CASPT2 level of theory. A stepwise mechanism through the triplet state of the homodimer is proposed for the pairs of nucleobases cytosine, thymine, and uracil involving a singlet−triplet crossing intermediary structure of biradical character representing the most favorable triplet state conformation of the nucleobases as found in the DNA environment. The efficiency of the mechanism will be modulated by two factors: the effectiveness of the triplet−triplet energy transfer process from a donor photosensitizer molecule, which relates to th…

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.

Benzen i metan jako wzorce przesunięcia chemicznego 1 H i 13 C NMR w obliczeniach teoretycznych

2020

NMR spectroscopy belongs to the most versatile techniques used in chemical laboratory for testing the presence of various compounds and elucidation of their structure. In case of more complex natural products chemical intuition and experience applied to analysis of experimental spectra is often supported by theoretical modeling of NMR spectra. However, theoretical predictions should be reliable and the errors associated with the approximations inherent to the existing methods minimized. In this respect, systematic errors, present in calculation of isotropic nuclear magnetic shieldings of the studied molecule need to be minimized. Conversion of nuclear shieldings of the studied molecule to 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).

Low-Dose Aclacinomycin and Intermediate-Dose Cytosine Arabinoside in Relapsed and Refractory Acute Myelogenous Leukemia

1990

Nineteen patients with relapsed or refractory acute myelogenous leukemia were treated with escalating doses of aclacinomycin (ACLA 20–30 mg/m2 daily for 5 days) and intermediate-dose cytosine arabinoside (Ara-C 1 g/m2 twice daily for 4 days). Most patients had received previous therapy with high- or intermediate-dose Ara-C plus mitoxantrone (HAM, IAM) and TAD (6-thioguanine, standard-dose cytosine arabinoside, and daunorubicin). Four patients had had repeated relapses and another three were treated for primary treatment failure following induction with HAM or I AM.

Eukaryotic rRNA Modification by Yeast 5-Methylcytosine-Methyltransferases and Human Proliferation-Associated Antigen p120.

2015

International audience; Modified nucleotide 5-methylcytosine (m(5)C) is frequently present in various eukaryotic RNAs, including tRNAs, rRNAs and in other non-coding RNAs, as well as in mRNAs. RNA: m(5)C-methyltranferases (MTases) Nop2 from S. cerevisiae and human proliferation-associated nucleolar antigen p120 are both members of a protein family called Nop2/NSUN/NOL1. Protein p120 is well-known as a tumor marker which is over-expressed in various cancer tissues. Using a combination of RNA bisulfite sequencing and HPLC-MS/MS analysis, we demonstrated here that p120 displays an RNA:m(5)C-MTase activity, which restores m(5)C formation at position 2870 in domain V of 25S rRNA in a nop2 Delta …