Two distinguishable fluorescent modes of 1-anilino-8-naphthalenesulfonate bound to human serum albumin. A time resolved flurescence spectrocopy study

SPRINGER/PLENUM PUBLISHERS

Lugar: Baltimore; Año: 1996 vol. 6 p. 33 - 33

e study the interaction of 1-anilino-8-naphthalenesulfonate (ANS) with human (HSA) and bovine serum albumin (BSA) by phase and modulation fluorescence spectroscopy. We determined that both HSA and BSA show one or two distinguishable fluorescent sites, depending of the ANS/serum albumin ratio. At above a 11 ANS/HSA molar ratio, the steady-state emission spectra for ANS can be resolved in two components: component 1, emitting with a lifetime (1) of 16 ns and a 1max of 478 nm, with a quantum yield (f1) of 0.67, and component 2, with a lifetime (2) of 2?4 ns and a 2max of 483 nm, with an average quantum yield (f2) of about 0.11. Considering these findings, the binding analysis is fitted with a model of two independent sites. Site 1 has an association constantK as1=0.87×106M?1 and a capacity of 1.04 mol of ANS/mol of HSA, and site 2 aK as2=0.079×106M?1 and a capacity of 2.34 mol of ANS/mol of HSA. Analysis of fluorescence lifetime distributions shows that the rigidity of the fluorophore en