Kinetic and thermodynamic study of beta-Boswellic acid interaction with Tau protein investigated by surface plasmon resonance and molecular modeling methods

Introduction: Beta-Boswellic acid (BBA) is a pentacyclic terpene which has been obtained from frankincense and its beneficial effects on neurodegenerative disorders such as Alzheimer’s disease (AD) have been addressed. Methods: In the present study, thermodynamic and kinetic aspects of BBA interaction with Tau protein as one of the important proteins involved in AD in the absence and presence of glucose has been investigated using surface plasmon resonance (SPR) method. Tau protein was immobilized onto the carboxy methyl dextran chip and its binding interactions with BBA were studied at physiological pH at various temperatures. Glucose interference with these interactions was also investigated. Results: Results showed that BBA forms a stable complex with Tau (KD=8.45×10-7 M) at 298 K. Molecular modeling analysis showed a hydrophobic interaction between BBA and HVPGGG segment of R2 and R4 repeated domains of Tau. Conclusion: The binding affinity increased by temperature enhancement, while it decreased significantly in the presence of glucose. Both association and dissociation of the BBA-Tau complex were accompanied with an entropic activation barrier; however, positive enthalpy and entropy changes revealed that hydrophobic bonding is the main force involved in the interaction

Study of interaction between nicotinamide and human serum albumin using spectroscopic techniques and molecular docking simulation simulation

Human serum albumin is one of the most important blood proteins that has the ability to bind a wide range of compounds and different drugs. Hence, knowing how drugs bind to albumin is crucial to understand their pharmacokinetics and pharmacodynamic properties. The binding of drugs to protein affects the drug's excretion, distribution and interaction in the target tissues. Nicotinamide (NA) is a safe and inexpensive medical supplement that used to prevent and treat vitamin B3 deficiency. In this research, the molecular mechanism of the interaction between nicotinamide and human serum albumin was studied by the utilization of spectroscopic and molecular docking methods. The effects of temperature, acidic/basic pHs, metal ions, urea, and glucose on the interaction between nicotinamide and human serum albumin were also investigated. The spectroscopic studies indicated that the interaction between nicotinamide and human serum albumin is mainly controled by hydrophobic forces and the interaction is spontaneous. The number of binding site and binding constant is 1 and 4.6×104 (L/mol), respectively, which were increased in the presence of glucose. The presence of metallic ions and basic pH decreased the binding constant of nicotinamide to albumin. The obtained results indicated that nicotinamide tend to binds to the similar sites wherever the molecules with acidic moieties bind. The results could be helpful to interpret the mechanisms of actions of nicotinamide in the various physiological phenomena in the human body