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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
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T2: P–7
Spectroscopic investigation of water structure around betaine
Marcin Stasiulewicz
1
, Aneta Panuszko
1
, and Janusz Stangret
1
1
Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology,
Narutowicza 11/12, 80-233 Gdańsk, Poland, e-mail: aneta.panuszko@pg.gda.pl
Betaine (N,N,N – trimethylglycine) belongs to a group of compounds called osmolytes [1].
Osmolytes are small organic compounds produced by living organisms to counteract harsh
environmental conditions [2]. Betaine increases salt tolerance in bacterial species of Listteria
monocytogenes and Lactococus lactis [3]. Also, it acts as a cryoprotectant in some prokaryotes
[4]. Moreover, thermal stability of proteins is increased in presence of betaine [5]. The addition
of betaine to a water solution of protein and urea (destabilizing osmolyte) prevents destruction
of tertiary structure of protein in presence of urea [6].
Study of betaine hydration in the range of temperature between 25–75°C was carried out by
means of FT-IR spectroscopy. This technique allows to investigation labile structures which are
created as a result of interactions between water and a solute. The isotopic dilution method of
semi-heavy water (HDO) in H
2
O was used to avoid most of experimental and interpretative
problems connected with H
2
O transmission spectra.
To extract spectra of affected water the difference spectra method was used [7]. This method
enables to study interactions inside hydration shells of osmolytes on the basis of analyzed series
of spectra of solutions with different concentrations of the solute. The betaine-affected water
spectrum gives valuable information about the energetic state of the hydrogen bonds of water
and intermolecular distances of hydrating water molecules.
Our results show that hydrogen bonds in hydration shell of betaine are shorter and stronger
in comparison to those in bulk water in whole range of temperatures and in this sense it could be
classified as a “structure making” osmolyte.
Keywords: betaine; osmolytes; hydration; difference spectra method; FT-IR spectroscopy
Acknowledgment
This work was supported by the Polish National Science Center (NCN) based on decision No. DEC-
2013/11/B/NZ1/02258.
References
[1] R.D. Sleator, C. Hill, FEMS Microbiol. Rev. 26 (2002) 49.
[2] P.H. Yancey, Am. Zool. 41 (2001) 699.
[3] D.O. Bayles, B.J. Wilkinson, Lett. Appl. Microbiol. 30 (2000) 23.
[4] D. Cleland, P. Krader, C. McCree, J. Tang, D. Emerson, J. Microbiol. Methods 58 (2004) 31.
[5] T. Caldas, N. Demont-Caulet, A. Ghazi, G. Richarme, Microbiology 145 (1999) 2543.
[6] J.B. Bateman, G.F. Evans, P.R. Brown, C. Gabriel, E.H. Grant, Phys. Med. Biol. 37 (1992) 175.
[7] M. Śmiechowski, J. Stangret, Pure Appl. Chem. 82 (2010) 1869.
XIV
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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
223
T2: P–8
Application of spectral methods for studying of DNA damage induced
by gamma-radiation
Svetlana Tankovskaia
1
, Omar M. Kotb
1,2
, Olga Dommes
3
, and Sofia Paston
1
1
Department of Molecular Biophysics and Polymer Physics, Faculty of Physics, Saint-Petersburg
State University, Ulyanovskaya, 3, St.Petersburg 198504, e-mail: Russia.tasva-ara1@yandex.ru
2
Department of Physics, Faculty of Science, Zagazig University, Sharkia Gov Zagazig, 4451 Egypt
3
Institute of macromolecular compounds, 199004 Saint-Petersburg, Bolshoy pr. 31, Russia
DNA damage is the main origin of cell death, mutation and cancer transformation. Therefore
DNA is considered to be the main target of ionizing radiation [1].
The most frequent types of radiation-induced DNA damages are modification and
destruction of nitrogenous bases and also local breakages of hydrogen bonds (partial
denaturation) in the lesion sites of the macromolecule [1]. To reveal the amount of these
damages we applied the UV absorption spectroscopy, spectrophotometric melting and circular
dichroism (CD).
Radiation-induced changes in DNA structure influence its UV absorption spectrum in
different ways: partial denaturation causes hyperchromic effect, while destruction of the bases
results in hypochromism. To recognize the chromophore loss in irradiated solution we apply the
Spirin’s method of nucleobases concentration measurement [2]. We obtained DNA absorption
and CD spectra, nucleobases concentration and melting temperature after gamma-irradiation
with the doses 0-1000 Gy in solutions with different ionic strength (0.005M and 3.2M NaCl)
and various DNA concentrations during the irradiation. Nucleobases concentration, melting
temperature and degree of DNA helicity decrease monotonously with the rise of dose. There is
strong dependence of the radiation effect on the DNA concentration (C(DNA)) in the irradiating
sample. DNA damage induced by the dose of 500 Gy was too hard that it was impossible to
observe the helix – coil transition. At the same time the melting temperature of DNA irradiated
in lyophilized form decreases weakly even after irradiation with the dose of 1000 Gy. The
dependences of radiation-chemical yield (Y) of bases destruction on C(DNA) obtained for doses
of 500 and 1000 Gy satisfactorily fit on one curve and evidence that at low DNA content in the
irradiated solution (С(DNA)=0–0.005%) the indirect action of radiation predominates. At that
not all water radiolysis products reach DNA molecules because of low DNA concentration. At
С(DNA)=0.005%–0.04% the plateau in the dependence Y=f(C(DNA) is observed. In this region
also the indirect action of radiation prevails, but all water radiolysis products reach DNA
molecules, so the yield is determined by dose but not by targets concentrations. Increase in
electrolyte concentration leads to lowering of DNA damage.
Keywords: DNA damage; gamma-irradiation; UV spectroscopy; spectrophotometric melting; circular dichroism
Acknowledgment
A part of this work was performed using the equipment of the Centre for Optical and Laser Materials
Research (COLMR), St. Petersburg State University.
This work was supported by the RFBR, project no. 15-08-06876.
References
[1] Yu. B. Kudryashov, Radiation Biophysics (Ionizing Radiations), New York: Nova Science Publishers,
Inc. (2008) pp. 327.
[2] A.S. Spirin, Biokchimiya (USSR) 23 (1958) 656.
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