SPECTROSCOPY FEATURES OF THE BINDING OF POLYENE ANTIBIOTICS TO HUMAN SERUM ALBUMIN
ROMANINI, DAIANA; AVALLE, GABRIELA; FARRUGGIA, BEATRIZ; NERLI, BIBIANA; PICO, GUILLERMO
Lugar: Shannon-Irlanda; Año: 1998 vol. 115 p. 247 - 260
Abstract 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 very high affinity (5.8 10 7 M-1) and a secondary binding site with an affinity two orders lower than the primary sites. This secondary binding site was very sensitive to temperature change. Nystatin yielded only one type of binding sites with an affinity of 1.1 10 5 M-1. Nystatin was found to be bound to the fatty acids binding sites in albumin, while Amphotericin B was not, suggesting that the binding sites for fatty acid are not simple, depending on the number of unsaturated bonds at the molecule of polyene antibiotic. 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.