(513d) Conformational Changes of Bovine Serum Albumin upon Adsorption on Nano-Sized Thermosensitive Magnetic Particles

Conformational changes of proteins in solution are well known phenomena and are important for substrate binding and regulation of enzyme activity. Adsorption of bovine serum albumin on nano-sized Thermosensitive polymer (N-isopropylacrylamide) (PNIPAM) coated magnetic particles were studied and desorption of BSA from magnetic particles were carried out in different desorption agents such as NaH2PO4, Na2HPO4, and Tween 80. Adsorption of BSA on the thermosensitive magnetic particles was dependent on the properties of the particle surface. By increasing the temperature above the LCST of PNIPAM the particles shrank and were able to adsorb larger quantity of proteins, which was subsequently desorbed at lower temperature. Conformational changes in bovine serum albumin upon adsorption on thermosensitive nano-particles have been studies by circular dichroism (CD) and fluorescence spectroscopy. The magnitude of conformational changes of protein was measured by calculating á-helix content from CD spectra. The extent of the result shows a large change in CD spectrum for native and desorbed protein indicating a larger conformational change. The extent of the changes in secondary structure of bovine serum albumin upon adsorption on thermosensitive nano magnetic particles varies with different desorption agent.

Keywords: N-isopropylacrylamide; Adsorption; Desorption; Conformational change; á-helix content.