Spectroscopy features of the binding of polyene antibiotics to human serum albumin

ROMANINI, DIANA; AVALLE, GABRIELA; FARRUGGIA, BEATRIZ; NERLI, BIBIANA; PICÓ, GUILLERMO

Chemico-Biological Interactions

Elsevier Science Ireland Ltd. Estocolmo

Año: 1998 vol. 115 p. 247 - 260

0009-2797

The alteration in the fluorescence spectra observed for the polyene antibiotics nystatin and amphotericin B in the presence of human serum albumin is due to a decrease in the polar character of the antibiotic environment when these are bound to the protein. Amphotericin B showed two types of binding sites, the first having a very high affinity (5.8107 M1) and a secondary binding site with an affinity two orders lower than the primary site. This secondary binding site was very sensitive to temperature change. Nystatin yielded only one type of binding site with an affinity of 1.1105 M1. Nystatin was found to be bound to fatty acid binding sites in albumin, while amphotericin B was not, suggesting that the fatty acid binding sites are not simple, depending on the number of unsaturated bonds on the polyene antibiotic molecule. Both polyene antibiotics displaced bilirubin bound to albumin, which is in agreement with the similarities of the affinity values of this chromophore and the polyene antibiotics with albumin.