Fluorescence behavior of tryptophan residues of bovine and human serum albumins in ionic surfactant solutions: A comparative study of the two and one tryptophan(s) of bovine and human albumins

Abstract

The fluorescence behavior of two tryptophans (Trp-134, Trp-213) in bovine serum albumin (BSA) and a single tryptophan (Trp-214) in human serum albumin (HSA) was examined. The maximum emission wavelength (λ_max) was 340.0 nm for both proteins. In a solution of sodium dodecyl sulfate (SDS), the λ_max of BSA abruptly shifted to 332 nm at 1 mM SDS and then reversed to 334 nm at 3 mM SDS. The λ_max of HSA gradually shifted to 330 nm below 3 mM SDS, although it returned to 338 nm at 10 mM SDS. In contrast to this, in a solution of dodecyltrimethylammonium bromide, the λ_max positions of BSA and HSA gradually shifted to 334.0 and 331.5 nm, respectively. Differences in the fluorescence behavior of the proteins are attributed to the fact that Trp-134 exists only in BSA, with the assumption that Trp-213 of BSA behaves the same as Trp-214 of HSA. The Trp-134 behavior appears to relate to the disruption of the helical structure in the SDS solution.