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

0277-8033

 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.