Apoenzyme membranes achieve chiral separations

Abstract

Enzymes stripped of their catalytic power are being used as molecular recognition agents to bind chiral molecules in solution and transport them across membranes. The innovative strategy could find use in pharmaceutical separations. Enzymes cannot generally be used for facilitated transport across membranes because they convert their substrates to products. This is particularly undesirable for biomedical or pharmaceutical separations, where one wants to obtain the substrate itself, not an enzymatically altered version. Graduate student Brinda B. Lakshmi and chemistry professor Charles R. Martin of Colorado State University, Fort Collins, have now done an end-run around the problem by using apoenzymes instead of complete enzymes for facilitated transport [Nature , 388, 758 (1997)]. An apoenzyme is an enzyme lacking its associated cofactor, which it needs to catalyze a reaction. We reasoned that without the cofactor the enzyme could still selectively recognize and bind its substrate, but it could not conve...