Use of amphotericin B as optical probe to study conformational changes and thermodynamic stability in human serum albumin |
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Authors: | Romanini Diana Müller Gabriela Picó Guillermo |
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Institution: | (1) Departamento de Quémica-Física and CONICET, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, Suipacha 570, (2000) Rosario, Argentina |
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Abstract: | The binding of polyene antibiotic amphotericin B to serum albumin was studied using absorption, fluorescence, and circular dichroism techniques. A hypochromic effect was observed in the absorption spectrum of amphotericin B in the presence of albumin with maxima at 366 nm, 385 nm, and 408 nm, which correspond to the absorption of the monomeric form of amphotericin B. A modification on the circular dichroism spectrum of amphotericin B in the presence of albumin was observed at bands 329 nm and 351 nm (excitronic interaction), which suggests that only amphotericin B monomer is bound to the protein. Amphotericin B perturbs the specific markers for sites I, II, and fatty acid binding site bound to these sites, suggesting that amphotericin B interacts with a great binding area in albumin. Lysines 199 and 525 in albumin participate in the molecular interaction between amphotericin B and the protein. The absorption spectrum of amphotericin B bound to albumin was sensitive to the chemical and thermal treatment of the protein, to neutral-basic transition of albumin and to conformational changes induced by the binding of other ligands to this protein. |
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Keywords: | Albumin stability polyene antibiotic amphotericin B optical probes |
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