The aim of the present study was to investigate in vivo toxic effects and to find acute toxic doses (LD50) of novel N-sulfonyl derivatives of pyrimidine nucleobases uracil and cytosine. Six N-1-sulfonyluracil derivatives (1, 2, 6, 7, 8, and 9) and two N-1-sulfonylcytosine (4, 12) and N-1,NH-4-disulfonylcytosine (13) were evaluated in this study. All experiments were performed on 10-14week-old m...

This review focuses on the contribution of translesion DNA polymerases to immunoglobulin gene hypermutation, in particular on the roles of DNA polymerase eta (Poleta) in the generation of mutations at A/T bases from the initial cytosine-targeted activation-induced cytidine deaminase (AID)-mediated deamination event, and of Polkappa, an enzyme of the same polymerase family, used as a substitute ...

The excited state lifetimes of DNA bases are often very short due to very efficient non-radiative processes assigned to the ππ*-nπ* coupling. A set of protonated aromatic diazine molecules (pyridazine, pyrimidine and pyrazine C4H5N2(+)) and protonated pyrimidine DNA bases (cytosine, uracil and thymine), as well as the protonated pyridine (C5H6N(+)), have been investigated. For all these molecul...

Expressed immunoglobulin (Ig) genes undergo alterations in sequence and genomic structure in order to optimize antibody function.A singleB cellspecific factor, activation-induced deaminase (AID), initiates these changes by deamination of cytosine to uracil. Uracil in DNA is encountered commonly, and conserved pathways are responsible for its faithful repair.However, at the Ig loci of B cells,AI...

DNA with abasic sites has been prepared by deamination of cytosine followed by treatment of the product with uracil N-glycosylase. Termination in vitro on such templates does not occur until treatment with uracil N-glycosylase. DNA terminated one base before abasic sites created from C's has been used as a template in "second stage" reactions. With enzymes devoid or deficient in 3' greater than...

Uracil-DNA-glycosylase (UDG) is the first enzyme in the base excision repair pathway for removal of uracil in DNA. The disturbance of reparation system results in occurrence of a number of diseases, including various kinds of a cancer. Uracil (Ura) in DNA may result from incorporation of dUMP instead of dTMP or from spontaneous deamination of cytosine in DNA. The majority of organisms delete th...

The spontaneous deamination of cytosine produces uracil mispaired with guanine in DNA, which will produce a mutation, unless repaired. In all domains of life, uracil-DNA glycosylases (UDGs) are responsible for the elimination of uracil from DNA. Thus, UDGs contribute to the integrity of the genetic information and their loss results in mutator phenotypes. We are interested in understanding the ...

The ultrafast radiationless decay of photoexcited uracil and cytosine has been investigated by ab initio quantum chemical methods based on CIS and CR-EOM-CCSD(T) electronic energy calculations at optimized CIS geometries. The calculated potential energy profiles indicate that the S(1) --> S(0) internal conversion of the pyrimidine bases occurs through a barrierless state switch from the initial...

Ultrafast decay processes detected after absorption of UV radiation in gas-phase pyrimidine nucleobases uracil, thymine, and cytosine are ascribed to the barrierless character of the pathway along the low-lying 1(pipi*) hypersurface connecting the Franck-Condon region with an out-of-plane distorted ethene-like conical intersection with the ground state. Longer lifetime decays and low quantum yi...

background: saccharomyces boulardii (s. boulardii) is the best known probiotic yeast. the genetic engineering of this probiotic strain requires the availability of appropriate mutants to accept various gene constructs carrying different selection markers. as the auxotrophy selection markers are under focus, we have generated a ura3 auxotroph mutant of s. boulardii for use in further genetic man...