A quantitative Secondary Structure analysis of BSA on Interaction with Oseltamivir phosphate by FT-IR Spectroscopy

Serum albumin are the major soluble protein constituents of the circulatory system and have many physiological functions including transporting a variety of compounds. The availability, high purity at reasonable cost of BSA and homologue structure with HSA, has made this protein favorite for study by chemists. Oseltamivir phosphate (OP; Tamiflu) is a prodrug of the anti-influenza neuraminidase inhibitor and has been developed for the treatment and prevention of both A and B strains of influenza. Infrared spectroscopy is one of the oldest and well established experimental techniques for the analysis of secondary structure of polypeptides and proteins. It is convenient, non-destructive, requires less sample preparation, and can be used under a wide variety of physical conditions. The polypeptide repeat units give rise to nine characteristic IR absorption bands, namely, amide A, B, and I-VII. The most sensitive spectral region to the protein secondary structural components is the amide I band (1600-1700 cm-1), which is due almost entirely to the C=O stretch vibrations of the peptide linkages. This study was designed to stability protein secondary structure by Fourier self-deconvolation and second-derivative analysis .The protein secondary structure showed no major alterations at low ligand concentrations (5µM), whereas at higher content (0.5 mM), decrease of α-helix from 63%(free BSA) to 41% and increase of β-sheet from 16%(free BSA) to 25% and Turn5% (free BSA) to 21% occurred in the ligand-BSA complexes. These observations indicated that low drug content induced protein stabilization (folding), whereas, at high drug concentration, a partial protein destabilization (unfolding) occurred in these drug-BSA complexes.

Keywords:

Bovine serum albumin , protein , Oseltamivir phosphate , Secondary structure , FT-IR.