Study On The Interaction Between Antiparasitic Drug And Bovine Serum Albumin And The Effect Of Metal Ions

Anti-parasitic drugs are one of the effective methods to prevent and control parasitic diseases.However,these drugs could remain in animal foods and enter the human body along the food chain endange human health.As one of the most abundant protein in vertebrate plasma,serum albumin（SA）can bind with many endogenous and exogenous substances the interaction mechanism of mebendszole（MBZ）and praziquantel（PZQ）with bovine serum albumin（BSA）under simulated physiological conditions（p H=7.4）were study spectroscopy.The effects of Fe³⁺and Cu²⁺on the interaction of MBZ and PZQ with BSA investigated as follows:1.The binding constants,the number of binding sites,the binding distance,and the binding sites of the interaction between MBZ and BSA were studied by fluorescence spectroscopy.The results showed that the quenching mechanism of the MBZ and BSA was mainly by static quenching.The binding constants of MBZ-BSA were 4.73×10⁴L·mol^-1、3.99×10⁴L·mol^-1and3.44×10⁴L·mol^-1at 298 K,303 K and 310 K.The number of binding sites n was about 1,indicating that a 1:1 complex was formed between MBZ and BSA.the thermodynamic constantΔH andΔS of MBZ and BSA were-20.33 k J·mol^-1and 3.22 J·mol^-1·K^-1respectively by the Van’t Hoff equation and the thermodynamic formula,The binding force were interaction between MBZ and BSA.The negativeΔG,indicated that the bingding process between MBZ and BSA was spontaneous.The results of FT-IR spectroscopy,circular dichroism,synchronous fluorescence spectroscopy,and UV-visible absorption spectroscopy revealed that MBZ induced conformationed changes of BSA.The results of site probe competition experiments showed that MBZ binds to the Site1 of BSA.2.The effects of metal ions Cu²⁺and Fe³⁺on the binding of MBZ to BSA were studied.The results showed that but Cu²⁺and Fe³⁺did not change the type of fluoreescence quenching of BSA by MBZ,it endance the quenching degree of BSA by MBZ.Cu²⁺and Fe³⁺increased the binding constant K_svof MBZ-BSA.It showed that metal ions could affect the interaction between MBZ and BSA.The presence of metal ions changed the main binding force of MBZ and BSA binding,from electrostatic attraction interaction to van der Waals forces.3.The interaction mechanism between PZQ and BSA was studied.From the results of fluorescence quenching experiments indicated that PZQ and BSA formed a complex through hydrogen bonding and Van der Waals force,which causes fluorescence quenching of BSA.The binding distance was 2.98nm between MBZ and BSA based on F?rster,non-radiative energy transfer,which indicated that the energy transfer was highly passible.The results of synchronous fluorescence spectra.From the synchronous fluorescence spectroscopy and ANS fluorescence spectra,showed that PZQ changed the hydrophobicity of tryptophan residue.From the UV-visible absorption spectra and circular dichroism spectra results,showed that PZQ changed the secondary structure of BSA.4.The effects of Cu²⁺and Fe³⁺on the interaction between PZQ and BSA were studied.The results showed that Cu²⁺and Fe³⁺change the quenching constants and binding constants of PZQ to BSA.Cu²⁺and Fe³⁺increased K_svand K_q.Cu²⁺increased the binding constant K_aof PZQ-BSA,while Fe³⁺decrease the binding constant K_aof PZQ-BSA.Cu²⁺and Fe³⁺did not change the fluorescence quenching types and force type of PZQ on BSA.