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Study of DNA damage on DNA G-quadrup...

Aggrawal, Manali.

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Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability./
作者:	Aggrawal, Manali.
面頁冊數:	242 p.
附註:	Source: Dissertation Abstracts International, Volume: 75-05(E), Section: B.
Contained By:	Dissertation Abstracts International75-05B(E).
標題:	Chemistry, Biochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3609355
ISBN:	9781303681608

Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability.
Aggrawal, Manali.

Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability. - 242 p.

Source: Dissertation Abstracts International, Volume: 75-05(E), Section: B.

Thesis (Ph.D.)--University of the Pacific, 2014.

This item is not available from ProQuest Dissertations & Theses.

Exposure of DNA to reactive oxygen species (ROS) results in the modified nucleobases (lesions) as well as strand scissions under physiological conditions. Due to its lowest oxidation potential (1.29 eV), guanine is the most easily oxidisable nucleobase. Furthermore, it has been observed that the 5'-guanine in G-tracts (e.g. GGG) has even lower oxidation potential (1.00 V vs. NHE). One of the representative G-rich examples is telomeres that consist of repeating units of 5'-d [TTAGGG]-3' found at the ends of chromosomes. Telomeres play an important role in biological functions, serving as guardians of genome stability; however, their G-rich nature implies that they can be readily oxidized. So how does nature protect these biologically important regions from oxidation? We believe the formation of a secondary structure known as G-Quadruplex in telomeric regions can partly serve as a protective role. In the first part of this work, we investigated DNA G-Quadruplex damage under various oxidation conditions and compare the damage results with single-stranded telomeric sequences. Damage to G-Quadruplex is generally less than single strands and is condition dependent. Guanines are the primary damage sites, but damage of adenine and thymine is also possible.

ISBN: 9781303681608Subjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability.
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245 1 0 $a Study of DNA damage on DNA G-quadruplexes and biophysical evaluation of the effects of modified bases (lesions) on their conformation and stability.
300 $a 242 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-05(E), Section: B.
500 $a Adviser: Liang Xue.
502 $a Thesis (Ph.D.)--University of the Pacific, 2014.
506 $a This item is not available from ProQuest Dissertations & Theses.
506 $a This item must not be sold to any third party vendors.
520 $a Exposure of DNA to reactive oxygen species (ROS) results in the modified nucleobases (lesions) as well as strand scissions under physiological conditions. Due to its lowest oxidation potential (1.29 eV), guanine is the most easily oxidisable nucleobase. Furthermore, it has been observed that the 5'-guanine in G-tracts (e.g. GGG) has even lower oxidation potential (1.00 V vs. NHE). One of the representative G-rich examples is telomeres that consist of repeating units of 5'-d [TTAGGG]-3' found at the ends of chromosomes. Telomeres play an important role in biological functions, serving as guardians of genome stability; however, their G-rich nature implies that they can be readily oxidized. So how does nature protect these biologically important regions from oxidation? We believe the formation of a secondary structure known as G-Quadruplex in telomeric regions can partly serve as a protective role. In the first part of this work, we investigated DNA G-Quadruplex damage under various oxidation conditions and compare the damage results with single-stranded telomeric sequences. Damage to G-Quadruplex is generally less than single strands and is condition dependent. Guanines are the primary damage sites, but damage of adenine and thymine is also possible.
520 $a Based on our studies, telomeric DNA can be readily oxidized to produce DNA lesions. How do DNA lesions affect the conformation and the stability of telomeric G-Quadruplex DNA? In the second part, we sought to address this question using various biophysical methods. Several native (OxodG, OxodA, and abasic site) and non-native (8-NH2-dA and 8-Br-dA) lesions were tested. UV thermal denaturation and circular dichroism revealed that the conformation and the stability of G-Quadruplex DNA are dependent on the location and the type of lesion in the sequence. G-Quadruplex DNA containing OxodG maintains its conformation with a decreased stability. Abasic site in the TTA loop affects the conformation of G-Quadruplex DNA but shows little effect on its stability. An unexpected stabilization of telomeric G-Quadruplex DNA was observed when deoxyadenosine (dA) in the loops was replaced with its native oxidized form OxodA. This is the first example of native DNA lesion that increases the stability of G-Quadruplex DNA. Like OxodA lesion, 8-NH 2-dA (a non native DNA lesion) increases the stability of G-Quadruplex DNA while 8-Br-dA only affects the stability in KCl but has no significant effect in NaCl. In addition, studies of the effect of OxodA lesion on the human telomerase activity using TRAP assay will be discussed.
590 $a School code: 0173.
650 4 $a Chemistry, Biochemistry. $3 1017722
650 4 $a Biophysics, General. $3 1019105
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