Nature of the alteration of the fluorescence spectrum of bovine serum albumin produced by the binding of dodecyl sulfate

Abstract

Interaction of dodecyl sulfate with bovine serum albumin altered the fluorescence spectrum of the protein. Binding of 12 equivalents of the ligand produced the entire effect. The spectral alteration proceeded in two stages. Quenching occurred during the first stage, whereas a blue shift and enhancement of intensity characterized the second stage. An influence of binding on the state of ionization of ε-amino groups in the long-chain ligand-binding sites and in the immediate vicinity of a tryptophan appeared to be partially responsible for the quenching. The blue shift and enhancement of intensity, observed in the second stage of the alteration, was caused by a more hydrophobic environment for tryptophan in the ligand-protein complex than in the non-complexed protein. Little influence on tyrosine fluorescence occurred.