Two distinguishable fluorescent modes of 1-anilino 8-naphthalenesulfonate bound to Human Albumin

LUIS A. BAGATOLLI; SILVIA C. KIVATINITZ; FELIPE AGUILAR; MARCO A. SOTO, ; CARLOS P. SOTOMAYOR ; GERARDO D. FIDELIO

JOURNAL OF FLUORESCENCE

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 1996 vol. 6 p. 33 - 33

1053-0509

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 1∶1 ANS/HSA molar ratio, the steady-state emission spectra for ANS can be resolved in two components: component 1, emitting with a lifetime (τ1) of 16 ns and a λ1max of 478 nm, with a quantum yield (фf1) of 0.67, and component 2, with a lifetime (τ2) of 2-4 ns and a λ2max of 483 nm, with an average quantum yield (фf2) 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=0.87×10(6)M(-1) and a capacity of 1.04 mol of ANS/mol of HSA, and site 2 aK as2=0.079×10(6)M(-1) and a capacity of 2.34 mol of ANS/mol of HSA. Analysis of fluorescence lifetime distri