REVERSIBLE BINDING INTERACTIONS BETWEEN THE TRYPTOPHAN ENANTIOMERS AND ALBUMINS OF DIFFERENT ANIMAL SPECIES AS DETERMINED BY NOVEL HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHODS - AN ATTEMPT TO LOCALIZE THE D-TRYTOPHAN AND L-TRYPTOPHAN BINDING-SITES ON THE HUMAN SERUM-ALBUMIN POLYPEPTIDE-CHAIN BY USING PROTEIN-FRAGMENTS

The stereoselectivity of the reversible binding interactions between t he D- and L-tryptophan enantiomers and serum albumins of different ani mal species and fragments of human serum albumin (HSA) was investigate d by applying three novel high performance liquid chromatographic (HPL C) arrangements. The separations were performed by means of 1) an achi ral (diol-bond), 2) a chiral (bovine serum albumin-bond) silica gel so rbent, and 3) a column switching technique which uses both the diol- a nd HSA-bond HPLC stationary phases. A polarimetric detector and/or an ultraviolet (UV) spectrophotometer were used to monitor the separation process. HPLC arrangement 3 allowed the evaluation of enantioselectiv e binding for D and L-tryptophan to different albumins and albumin fra gments. At present, column switching can be considered the technique o f the broadest applicability for investigating the reversible binding interactions between a protein and drug enantiomers. (C) 1997 Wiley-Li ss, Inc.