发表于 2017-04-21 16:22
报告人：Valeriy M. Yashchuk（Taras Shevchenko National University of Kyiv, Ukraine）
摘要：Telomeres are the end part of the chromosomal DNA strand that contains a large number of repeated nucleotide sequences (TTAGGG for vertebrates). They serve as the caps at the end of each DNA strand, protecting chromosomes from deterioration. It is known that the telomeres are truncated during cell division. When they get too short, the cell can no longer divide. The telomere shortening process is associated with aging, cancer and a higher risk of death. That is why the understanding of the properties and behavior of telomeres are vitally important.
Optical spectroscopy provides a powerful tool for the telomere studies and this talk reports the results of the investigations of the photophysical properties of telomeres, in conjunction with general photophysics of DNA. It has been confirmed that main centers of optical absorption in telomeres are A, T, G bases and G-G-quadruplexes. The fluorescence of the studied telomere fragment is found to be not just combination of the emissions from the telomere nucleotides, but it can be associated with contribution from two emitting centers with lowest S1 energy levels: guanine bases and long-wave singlet excitations traps (possibly, G-G-quadruplexes). Phosphorescence of the telomeres is found to be associated with AT-sequences. The ratio of phosphorescence and fluorescence yields is found to be increased in telomeres as compared to that in DNA. Obtained data suggest an existence of the efficient triplet electronic excitation energy transfer (EEET) in telomeres, which can greatly affect their stability.
简历：Prof. Dr. Valeriy M. Yashchuk is a Head of Experimental Physics Department of Taras Shevchenko National University of Kyiv, Kyiv, Ukraine. He holds his Ph.D. and Doctor of Sciences (D.Sc.) degrees in physics from the same university. His scientific expertise lies in a field of area of photonics of organic media, he has published more than 250 peer-reviewed articles in this and related domains.
Prof. Yashchuk’s current research interests include:
• Electronic excitation energy transfer in macromolecules
• Organic light emitting diodes, solar photovoltaics
• Processes of aging and degradation of organic systems
• Photophysics of biological objects
• Photoinduced therapy of cancer and other diseases.
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