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Conference: Bucharest University Faculty of Physics 2011 Meeting

Section: Biophysics; Medical Physics

Title:

Investigation of the secondary structure of serum albumins in the presence of dextran molecules

Authors:

Claudia Chilom, Gabriel Baranga, Viorica Vaduva, Doina Gazdaru, and Aurel Popescu

Affiliation:

Research Centre in Molecular Biophysics, Department of Electricity, Solid State and Biophysics,

Faculty of Physics, University of Bucharest

E-mail

claudiafir@gmail.com

Keywords:

serum albumin, secondary structure, dextran, ATR-FTIR

Abstract:

Serum human and bovine albumins are the major components of the blood plasma, with a very important role both in bioregulation and blood transport phenomena. Dextrans are polysaccharides, which transported by blood plasma, are used as antithrombotic agents to reduce blood viscosity, as blood volume expander, in anemia, in the osmotic stress technique for applying osmotic pressure upon biological molecules, in some size - exclusion chromatography matrices, in biosensor immobilization, etc. The serum human and bovine albumins were investigated, by ATR - FTIR technique, in interaction with dextran molecules (10–500) kDa. We monitored: a) the direct correlation between the IR amide I and amide II band frequencies of albumins and of their complexes with dextrans and b) the changes in the secondary structure elements of these proteins upon dextran binding, as a function of buffer type. To do this, we computed the difference spectra (i.e., the complex spectra – the ligand spectra). All the spectra were recorded in three buffers solutions: Hepes, Tris - HCl and potassium phosphate. Spectra analysis shows that changes in the albumin secondary structure elements are more pregnant, in Tris-HCl buffer, than those observed in the Hepes and potassium phosphate buffers, for both albumins. The ATR-FTIR difference spectra, that is, the difference, complex – dextran, shows significant changes in the amide I and amide II bands (that are more evident in Tris-HCl than in Hepes and potassium phosphate buffers), as compared to the non complexed protein spectra recorded in the same conditions. These preliminary results prove the binding of the dextrans to the human and bovine albumins.