The influence of sodium phosphate buffer on the stability of various proteins: Insights into protein-buffer interactions

Present study delineates the effects of sodium phosphate buffer (PBS) solutions on the stability of various proteins including lysozyme (Lys), bromelain (BM), hemoglobin (Hb), and human serum albumin (HSA). Different spectroscopic methods such as UV–visible, steady state fluorescence, temperature dependent fluorescence spectroscopy, Fourier transforms infrared spectroscopy (FTIR), circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) show that PBS buffer protects protein structures. Efficacy of PBS stabilization from external additive factors follows order as lysozyme > BM > Hb. The thermal stability of HSA in PBS buffer solution was not detected, since no distinct and clear fluorescence transition was observed. However, results from other biophysical techniques reveal the native structure of HSA stabilized in presence of PBS. Moreover, increasing concentration of PBS also provides structural stabilization of HSA. This confirms the potentiality of PBS buffer as protecting agents for the proteins/enzymes. However, in case of Hb structure perturbed with the addition of higher concentrations of PBS. Our study confirms that efficacy of protein stabilization depends on type and concentration of buffer used. The present study is very useful for providing the alternative media to replace traditional volatile organic compounds or expensive modern solvents for biochemical applications.