Human serum albumin(hsa) as the most abundant carrier protein in blood plasma has been widely studied. hsa is often used as a model to study of the drug and protein interaction. the interaction between methotrexate with hsa has been studied from thermodynamic and structure point of view.
Methods
The thermodynamic values, gibbs free energy and the protein melting point, are obtained through thermal denaturation of protein both with and without methotrexate by thermal scanning of protein emission using the fluorescence spectroscopy technique. these methods evaluated the structure and stability of hsa.
Results
Tm values in melting point(tm) of hsa in the absence of these compounds were calculated 320.9 k and in the presence of 50 and 100µm methotrexate were obtained 318.4 and 318.5k, respectively. Δgo (298k) of hsa in the absence of methotrexate were measured 41.14 kj/mol and in the presence 50 and 100µm methotrexate were obtained 39.4 kj/mol and 15.2 kj/mol , respectively.
Δgh2o from chemical denaturation of hsa with urea was calculated 13.43 kj/mol in the absence of ligands, and 11.63 kj/mol in the presence of 50µm methotrexate and 11.1 kj/mol for 100µm concentration of methotrexate.
cm value of the protein in the absence of the aforementioned compounds was 1.57 m and in the presence of methotrexate 50µm and 100µm were 2.06m and 2.03m, respectively.
Conclusion
Intrinsic fluorescence studies showed that methotrexate decrease the intrinsic fluorescence intensity at 300-450 nm which consequently results in the instability of the protein structure of hsa.
Keywords
Keywords: human serum albumin, methotrexate, stability, fluorescence, denaturation
