Comparative Studies on the Interaction of Putrescine with Acid phosphatase by Multispectroscopic

The effect of putrescine on the Kinetics, conformation, and dynamics of native acid phosphatases was studied by thermal stability, intrinsic fluorescence, circular dichroism (CD), uitraviolet-visible (UV-vis) spectroscopy, and kinetic measurement, at the temperatures of 298 and 308 K. The Stern-Volmer quenching constants (Ksv) for the acid phosphatases-putrescine complex were obtained at two temperatures, revealing that putrescine quenched the intensity of acid phosphatases through the static mode of the quenching mechanism. The corresponding themodynamic parameters, Gibbs free-energy, enthalpy, and entropy change, showed that the binding process was spontaneous. These values and the molecular docking technique revealed that the hydrogen bonding and van der Waals forces played a major role in stabilizing the complex. CD,absorption, and fluorescence results also indicated that putrescine binding had a partial effect on acid phosphatases structure. putrescine could also influence the activity of acid phosphatases. Upon putrescine binding, the Vmax value of the enzyme was fixed and the Kcat/ Km values were enhanced slightly. The Tm of the putrescine - acid phosphatases complex was enhanced probably due to the higher H-bond formation and lower surface hydrophobicity after putrescine modification, as confirmed by UV-vis spectroscopy and fluorescence spectra. UV absorption and CD studies also indicated that the binding of putrescine to acid phosphatases had induced microenvironmental changes around the enzyme, leading to changes in its secondary structure.

Keywords:

Enzymes , Putrescine , Circular dichroism , Fluorescence analyzis , Thermal stability