USE OF AMPHOTERICIN B AS OPTICAL PROBE TO STUDY CONFORMATIONAL CHANGES AND THERMODYNAMIC STABILITY IN HUMAN SERUM ALBUMIN
ROMANINI, DIANA; MÚLLER, GABRIELA; PICO, GUILLERMO
JOURNAL OF PROTEIN CHEMISTRY
Kluwer Academic/Plenum Publishiers
Lugar: Nueva York; Año: 2002 vol. 21 p. 505 - 514
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 corresponds 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, neutral-basic transition of albumin and conformational changes induced by the binding of other ligands to this protein.