RESUMO
Thermal conformational changes in human serum albumin [HSA] in present with a 10 mM phosphate buffer, at pH=7 have been investigated via circular dichroism [CD] and UV spectroscopic methods. The results indicate that temperature in a range of 25oC to 55oC could induce a reversible conformational change in the structure of HSA. The HSA phase transition corresponds to the physiological and pathological conditions of the body, especially fever. The conformational change observed in HSA is accompanied by a mild conversion of its secondary structures. Acetaminophen is a papular pain killer, and HSA is used as a drug carrier. Hence, acetaminophen could it interact with HSA. The study of HSA - acetaminophen interaction reveals the effects of acetaminophen on HSA structure, preventing it's phase transition. HSA - acetaminophen interaction leads to the stabilization of HAS. This interaction is accompanied with 8 kJ/mol of free energy change. The structural changes within HSA due to it's interaction with acetaminophen could be considered as a drug side effect and it may affect the protein functions