Enantiorecognition in a multi-component environment.

We demonstrate that enantiopreference in the binding of , over , astaxanthin (AXT) to albumin manifests itself only for racemic (but not enantiopure) carotenoids. The observed enantioselectivity is rationalized using chiroptical spectroscopies supported by molecular docking, molecular dynamics and quantum-chemical calculations. These methods offer a plausible explanation for the observed enantiopreference, as they reveal a unique binding mode of the (3,3')-AXT form with the protein in contrast to multiple (random) possibilities for albumin binding with the (3,3')-AXT, and also a higher interaction energy of the latter enantiomer with the protein.