OPTICAL RESOLUTION OF AMINO-ACIDS BY ULTRAFILTRATION MEMBRANES CONTAINING SERUM-ALBUMIN

Ultrafiltration experiments for optical resolution of racemic phenylal anine and leucine were performed in a solution system containing bovin e serum albumin (BSA) and by using immobilized BSA membranes. It was f ound that D-phenylalanine preferentially existed in the permeate at pH 7.0 due to the binding of BSA to L-phenylalanine and that the concent ration ratio Of D-isomer to L-isomer in the permeate increased with a decrease in the feed concentration of the racemate in the solution sys tem. This observation is explained by a site saturation mechanism. A m inimum point was observed in the plot of the separation factor vs. fee d concentration of leucine for the optical resolution of leucine in th e solution system. It is suggested that BSA in the solution has two bi nding sites to leucine (i.e., binding sites to D-leucine and L-leucine ). It was found that the immobilized BSA membranes efficiently demonst rated optical resolution of racemic amino acids, although the racemic amino acids were optically resolved less effectively in the ultrafiltr ation using the immobilized BSA membranes than in the BSA solution.