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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:43 |
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Conference: Bucharest University Faculty of Physics 2015 Meeting
Section: Biophysics; Medical Physics
Title:
Infrared spectroscopy investigation of protein flexibility in solutions at different values of concentration and pH
Authors:
Loredana GHICA, Răzvan AIRINI,Octavian CALBOREAN, Dan F. MIHAILESCU
Affiliation:
University of Bucharest, Faculty of Biology, Departament of Anatomy, Animal Biology, Animal Physiology, Biophysics and Neurobiology
E-mail
danutza_ene@yahoo.com
Keywords:
crowded environment, FTIR spectroscopy, flexibility, pH
Abstract:
Introduction
In the cellular environment protein interactions occur at high concentrations (particular to crowded environment). This modifies their structure and properties.
The pH value of the protein solution strongly influences the conformation, the stability and the solubility of the molecules. Progress in the field of lasers and computing resources development has enabled Fourier transformation of the data obtained by IR spectroscopy. The spectrum obtained by Fourier Transform InfraRed- FTIR is specific to the analyzed sample.
Materials and methods
We used BSA (bovine serum albumin) solution at 8 pH values (2.2, 3, 4, 5, 6, 7, 7.4 and 8) and at 12 protein concentration values (0%, 1%, 2%, 3%, 4%, 5%, 7.5%, 10%, 12.5%, 15%, 20% and 25%) in a universal buffer consisting of Na2HPO4 and citric acid. After that, we measured the spectra in Mid-IR domain (400-4000 cm-1) for the 96 solutions using the FTIR Bruker Tensor 27 spectrometer.
Results
We have noticed that the order of the absorption at the 8 pH values significantly changes depending on the concentration. Thus, at lower concentration values, the protein absorption at the two wavelengths (~1654 cm-1 and ~1539 cm-1) has the lowest pH values - namely 2.2, 3 and 6. At 25 % solution concentration (as in the crowded cellular environment), the smallest absorption values occur at pH 4, 5 and 7. At the mentioned wavelenghts, the buffer absorbs the least at pH 7.4 and 2.2.
Conclusions
As a result of the spectra analysis we realized that the absorption value at ~1654 cm-1 and ~1539 cm-1 increases in a nonlinear way with the BSA concentration at different pH values, a fact that may be assigned to the crowded environment effect.
References:
1.Lopes,A., Sacquin-Mora,S., Dimitrova,V., Laine,E., Ponty,Y., Carbone,A.,Protein-Protein Interactions in a Crowded Environment: An Analysis via Cross-Docking Simulations and Evolutionary Information.
December 5, 2013DOI: 10.1371/journal.pcbi.1003369
2.Shai, Y., ATR-FTIR studies in pore forming and membrane induced fusion peptides.Biochim Biophys Acta. 2013 Oct;1828(10):2306-13. doi: 10.1016/j.bbamem.2012.11.027
3.Tatulian, S.A., Structural characterization of membrane proteins and peptides by FTIR and ATR-FTIR spectroscopy.Methods Mol Biol. 2013;974:177-218. doi: 10.1007/978-1-62703-275-9_9.
4.Kamerzell,T.J., Middaugh C.P., The complex inter-relantionships between flexibility and stability. J.Pharm.Sci.97,3494-3517, 2008
Acknowledgement:
Dan Florin Mihăilescu,
Răzvan Airini,
Octavian Calborean
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