Structural Studies on the interaction between putrescine and bovine serum albumin

The major soluble protein constituents of the circulatory system is Serum albumin. This protein have many physiological functions. The most important property of this group of proteins is that they serve as transporters for a variety of compounds such ad different drugs. Bovine Serum Albumin (BSA) is a single-chain polypeptide whit 583 amino acids that is folded into three homologous domains, each of which contains two subdomains (A and B). The BSA polypeptide contains two tryptophan residues (Trp134 and Trp213) and in the folded BSA molecule, Trp134 is located on the surface, and Trp213 is located in a hydrophobic pocket. Polyamines such as putrescine can interact with negatively charged molecules. The effect of putrescine on the structure of BSA has been investigated using the method of UV-Vis spectroscopy, fluorescence spectroscopy and molecular docking at temperature 298 K and 308 K in pH 7.4 using tris-HCl as a buffer. The complex formation between putrescine and BSA was detected as a change in the absorbance at 280 nm. The intensity of peak slightly increases after the addition of putrescine. The addition of putrescine alters the folding of BSA and decreases the hydrophobicity of the microenvironment of the Trp residues in the internal hydrophobic region. The static type of quenching mechanism was mainly involved in the quenching of intrinsic emission of the enzyme. The fluorescence quenching data (Ksv) for complex BSA-putrescine showed one binding site for putrescine. The negative value of Gibbs free energy change (ΔG0) suggested that the binding process was spontaneous.