INQUINOA   21218
INSTITUTO DE QUIMICA DEL NOROESTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of Sensitizers Bound to Bovine Serum Albumin on the Protein Structure and Aggregation Properties
Autor/es:
A. E. LEDESMA; R. CHEIN; C. D. BORSARELLI
Lugar:
Salta
Reunión:
Encuentro; 3rd LATIN AMERICAN PROTEIN SOCIETY MEETING; 2010
Institución organizadora:
SAB-CeBEM-LAPSM
Resumen:
The main physiological function of serum albumins is the transport of fatty acids. However, albumins can also associate and transport a large variety of small molecules. Many of these molecules can act as sensitizers upon irradiation with visible light, triggering a several photooxidation processes that modify the protein structure and/or conformation. In this report we investigated the interaction of bovine serum albumin (BSA) with organic and inorganic sensitizer molecules, such as the anionic rose bengal (RB) and eosine yellowish (EY), and the cationic methylene blue (MB) and ruthenium (II) tris-bipyridine complex (Rubpy) using fluorescence and infrared spectroscopies. The fluorescence analysis indicated that anionic sensitizers preferentially binds to site I of BSA, while cationic localizes predominantly in the site II. In presence of both type sensitizers, the temperature-dependent FTIR spectrum of BSA showed the increament of the bands at 1614 and 1683 cm-1 indicating a larger formation of interchain b-sheet hydrogen bonds. Similar kinetic curves of fibrillation were obtained by Thioflavin-T (TFT) fluorescence and by total second-order scattering (TSOS) at 65 ºC. The aggregation lifetime was shortened in presence of sensitizers, according with the increment of b-sheet structure observed by FTIR. However, the final TSOS was reduced about 20% probaly indicating differences in shape and/type of amyloid aggregates. The light irradiation of the sensitizer-BSA complex up to 50% of Trp oxidation did not change the fibrillation kinetics. The results are explained as a function of the sensitizer-protein interaction.