XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
230
T2: P–15
AFM-IR in studies of the protein secondary structure changes in clear
and opaque human lenses
C. Paluszkiewicz
1
, N. Piergies
1
, P. Chaniecki
2
, M. Rękas
3
,
J. Miszczyk
2
, and W.M. Kwiatek
1
1
Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland
e-mail: czeslawa.paluszkiewicz@ifj.edu.pl
2
5th Military Hospital with Polyclinic in Krakow, Ophthalmology, PL-30091 Krakow, Poland
3
Military Medical Institute, Ophthalmology, PL-04141 Warszawa, Poland
Cataract is a common age-related disease, which causes lens clouding, mainly observed in
the crystalline lens. It decreases focusing of light and interferes producing clear and sharp
images [1]. According to the World Health Organization, cataract is responsible for 51% of
world blindness, which represents about 20 million people.
Here, we present the first approach to vibrational characterization of human lenses affected
and non – affected by cataract development in nanoscale resolution [2]. Fig. 1 shows AFM
images of the two investigated tissues and Amide I/.Amide II intensity maps. The obtained
results indicate that the application of the AFM – IR spectroscopy technique allowed for better
understanding structural changes connected with advancing disease process in studied lenses.
Briefly, the domination of the β–turn protein secondary structure is observed in the clear (non -
affected by cataract) lens. While, in the case of the opaque (cataractous) samples the two
different proteins secondary structures, namely β–turn/ β–sheet parallel and anti-parallel β–
sheet, are recognized. These structural variations suggest that the degradation due to the cataract
development occurs in different degree. This could be associated with the formation of β-sheet
anti-parallel structure where the hydrogen bonding are known as more linear and thus more
stable than in the case of the β-sheet parallel [3].
Fig. 1. AFM image 2x2 μm of lens section of the clear (A) and opaque (C) human tissues coupled
with the Amide I/Amide II intensity ratio maps (B and D, respectively).
Keywords: infrared spectroscopy with atomic force microscope (AFM–IR); human lenses; cataract
Acknowledgment
This project has been supported by the National Science Centre Poland under decision no. DEC-
2012/05/B/ST4/01150. This research was performed using equipment purchased in the frame of the project
co-funded by the Małopolska Regional Operational Program Measure 5.1 Krakow Metropolitan Area as an
important hub of the European Research Area for 2007-2013, project No. MRPO.05.01.00-12-013/15.
References
[1] Z. Zhuang, M. Zhu, Y. Huang, J. Liu, Z. Guo, K. Xiong, N. Li, S. Chen, X. Qiu, Appl. Phys. Lett. 101
(2012) 173701.
[2] C. Paluszkiewicz, N. Piergies, P. Chaniecki, M. Rękas, J. Miszczyk, W. M. Kwiatek, J Pharm Biomed
Anal. 139 (2017) 125.
[3] R. Singh, Bioinformatics, genomics and proteomics, Vikas Publishing House PVT LTD, India, 2015.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
231
T2: P–16
Molecular organization of a prenylated chalcone xanthohumol in
dipalmitoylphosphatidylcholine monolayers:
a linear dichroism-FTIR study
Marta Arczewska
1
, Barbara Gieroba
2
, and Mariusz Gagoś
2
1
Department of Biophysics, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin,
Poland, e-mail: marta.arczewska@up.lublin.pl
2
Department of Cell Biology, Maria Curie-Skłodowska University, 20-033 Lublin, Poland
Numerous studies indicate that hop-derived prenylflavonoids are becoming more popular
due to their potentially interesting biological effects. Among them, xanthohumol (2',4',6',4-
tetrahydroxy-3'-prenylchalcone; XN), the most abundant flavonoid present in the female hop
plant (Humulus lupulus) , has gained the most attention because of its multiple health-promoting
properties [1–3]. The effect of xanthohumol on the organization of lipid membranes formed with
dipalmitoylphosphatidylcholine (DPPC) was studied with application of Langmuir technique
and linear dichroism-FTIR spectroscopy.
The two-component monolayers of various molar ratios of XN were formed at the air/water
interface, and the surface pressure versus molecular area isotherms were recorded upon
compression. These results revealed that the these components were only miscible at low molar
fraction of xanthohumol and the ejection of XN molecules at high surface pressures was
observed.
The analysis of the FTIR spectra of the mixed monolayers deposited onto a solid surface at
the surface pressure values of 6 mN/m and 25 mN/m showed that xanthohumol induce a small
disordering of the hydrocarbon chains, and has a major effect on the head-group dynamics.
Nevertheless, XN did increase the mobility of the lipid acyl chains, which may cause a
fluidizing effect on the monolayer. On the other hand, quite distinct structural changes were
observed for the phosphate groups and carbonyl groups in lipid ester similar to our previous
study [4]. It suggests the possibility of polar interactions of xanthohumol with the lipid matrix
via hydrogen bonding between the DPPC polar head groups and the hydroxyl moiety and the
carbonyl groups of XN molecules. The mean orientation angle θ between the molecular axis and
the normal to monolayer surface has been determined by the FTIR linear dichroism
measurements. The mean value of the angle between normal to monolayer surface and the main
axis of the acyl chain is approximately 26° for DPPC, while for the monolayer containing XN it
is approximately 15°. The changes in the orientation of hydrocarbon chains indicate a clear
influence on the dynamic and structural properties of the lipid monolayer.
In summary, xanthohumol incorporated into model lipid system changes the properties of
membrane that can be followed by the intracellular alterations being essential for its
pharmacological activity used in cancer or other disease treatment.
Keywords: prenylated chalcones; lipid monolayers; FTIR linear dichroism
Acknowledgment
The research was carried out with a Bruker Vector 3300 FTIR spectrometer purchased thanks to the
financial support of the European Regional Development Fund in the Framework of the Polish Innovation
Economy Operational Program (contract no.POPW.01.03.00-06-009/11).
References
[1] C. Dorn, J. Heilmann, Int. J. Clin. Exp. Patho. 5 (2012) 29.
[2] J.F. Stevens, J.E. Page, Phytochemistry 65 (2004) 1317.
[3] Y. Wang, Y. Chen, J. Wang, J. Chen, B.B. Aggarwal, X. Pang, M. Liu, Curr. Mol. Med. 12 (2012)
153.
[4] M. Arczewska, D.M. Kaminski, E. Gorecka, D. Pociecha, E. Roj, A. Slawinska-Brych, M. Gagos,
Biochim Biophys Acta 1828 (2013) 213.
Dostları ilə paylaş: |