期刊
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
卷 225, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.saa.2019.117464
关键词
Electron transfer; Molecular crowder; Fluorescence quenching; Time-resolved fluorescence spectroscopy
类别
资金
- authority of SNBNCBS
- Ministry of Electronics and Information Technology, Government of India
- Visvesvaraya PhD Programme of Ministry of Electronics & Information Technology (MeitY), Government of India
- Science and Engineering Research Board, Government of India [EMR/2016/006555]
- Indian Institute of Technology Kanpur
Long distance electron transfer (ET) between small ligands and DNA is a much studied phenomenon and is principally believed to occur through electron (or hole) hopping. Several studies have been carried out in aqueous environments while in real biological milieu the DNA molecules experience a more dense and heterogeneous environment containing otherwise indifferent molecular crowders. It is therefore expected that the ET could get modified in the presence of crowding agent and to investigate that we have made elaborate studies on steady state and time-resolved (picosecond (ps) and femtosecond (fs)-resolved) emission properties of a phenosafranine (PSF) intercalated to calf thymus (CT) DNA in the presence of ethylene glycol (EG) and polyethylene glycols (PEG) of different chain lengths (PEG 200, 400 and 1000). The emission of PSF gets considerably quenched when intercalated to DNA; the quenching is released when PEGs are added into it. The structural integrity of the CT DNA has been established using circular dichroism spectroscopy. CD measurements have evidenced only marginal changes in the DNA structure upon the addition of PEGs. ps-Resolved fluorescence measurements show significant decrease in the contribution of the DNA induced quenched time-constant of PSF upon the addition of PEGs, however, fs-resolved measurements show less noticeable changes in the time constants. Our study shows that the electron hopping rate through the guanine base in DNA core remains unaffected whereas the 'through space' electron transfer process does get affected in the presence of molecular crowders. (C) 2019 Published by Elsevier B.V.
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