China
Africa
Explore chapters and articles related to this topic
Pyrimidines
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Nicoleta A. Dudaş, Mihai V. Putz
From this experimental work one or more pyrimidinic derivatives were obtained: uracil, cytosine, is cytosine, thymine, 5,6-dihydrouracil, orotic acid, 4(3H)-pyrimidinone, 2(1H)-pyrimidinone, purine, adenine, guanine, hypoxanthine, 2-aminopurine (Figure 41.10) and the yield of pyrimidine nucleobases increased by increasing the amount of iron in the catalyst (Saladino, 2012, 2013a,b).
Theoretical studies on the electronic and optoelectronic properties of [A.2AP(w)/A*.2AP(WC)/C.2AP(w)/C*.2AP(WC)/C.A(w)/C*.A(WC)]–Au8 mismatch nucleobase complexes
Published in Molecular Physics, 2018
The synthesis of DNA is carried out with high precision, which is very important for maintaining the genetic information to generations. Yet, errors arise during DNA replication, which further causes the structural imperfections between improperly paired nucleotides, and become permanent mutations. These accidental changes in genomic DNA sequence, mutations [1], can be harmful to a cell, in which they occur; change the functions of proteins and cause aging, illnesses and inherited diseases [1–4]. Spontaneous mutations occur during DNA replication due to many factors such as clarification of the incorrect DNA base pairs, endogenous chemical lesions generated spontaneously during normal metabolic process, errors in cellular processes and transposable genetic elements [5]. The substitution of one nucleotide from other might be the other reason. The common cause for these mutations is the formation of the enzymatically competent Watson–Crick (WC)-like G*·T(WC) [6] and A·C*(WC) [7] DNA base pairs and mutagenic tautomers, which are marked by the asterisks, in the recognition pocket of the high-fidelity DNA-polymerase in its closed conformational state. Therefore, the mechanisms of the origin of mutations in this area are an intensive topic of research. These mutations are classified as duplications, inversions and chromosomal rearrangements, deletion and insertions and point mutations [8–10]. The point mutations can be further classified into base pair substitutions/transitions and transversions. The average frequency range of spontaneous point mutations in vitro is supposed to be dependent on the concentration of deoxynucleotide substrates, the enzyme–template/primer interaction and the properties of DNA polymerase. Among the six possible transversions (A.A, G.G, A.G, C.C, T.T and C.T), the A.G, C.T and C.C transversions are not eliminated from the genome of Escherichia Coli, for which the efficiency rate of removal of DNA biosynthesis error is highest. 2-aminopurine (2AP) is the highly energetic isomer of adenine base [11], which differs only by the position of the exocyclic amino group. All irregular DNA base mispairs, which are actively involved in the field of spontaneous mutagenesis, have been identified as a result of painstaking experimental, as well as theoretical efforts.