SPECTROSCOPY FEATURES OF THE BINDING OF POLYENE ANTIBIOTICS TO HUMAN SERUM ALBUMIN

ROMANINI, DAIANA; AVALLE, GABRIELA; FARRUGGIA, BEATRIZ; NERLI, BIBIANA; PICO, GUILLERMO

CHEMICO-BIOLOGICAL INTERACTIONS

ELSEVIER

Lugar: Shannon-Irlanda; Año: 1998 vol. 115 p. 247 - 260

0009-2797

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.