Chiral discrimination between D- and L-tryptophan based on the alteration of the fluorescence lifetimes by the chiral additives

The chiral microenvironmental properties of bovine serum albumin. cyclodextrins and their mixtures were comparatively investigated based on pyrene as the fluorescence probe. On this basis, a time resolved fluorescence technique to discriminate D- and L-tryptophan (Trp) without separation was developed This method was based on the quenching rate difference between D- and L-Trp to pyrene in various media Including bovine serum albumin, cyclodextrins and their mixtures. Pyrene, tryptophan and bovine serum albumin (or cyclodextrin) could form ternary complexes, which provided a possibility for the discrimination of D- and L-Trp enantiomers. The results indicated that the chiral discrimination of Trp enantiomers could be obtained in the mixture system of gamma-cyclodextrin and BSA system, in which the fluorescence lifetime difference (Delta tau) and the lifetime difference percentage (Delta tau/tau) were 55.8 ns and 28 50%, respectively (C) 2010 Elsevier B V All rights reserved.