Optimization of the enantiomeric separation of tryptophan analogs by membrane processes

The separation of racemic tryptophan analogs has been performed by two ways : ultrafiltration in a solution system using bovine serum albumin (BSA) as a free chiral selector and dialysis using BSA grafted nylon membrane. A com plexation mechanism based on competitive binding of both D- and L-tryptopha n zwitter-ionic form on the same unprotonated protein site has been used to predict recovery and purity of both D- and L-tryptophan in the retentate a nd permeate. The corresponding model gave correct prediction for a large se t of experimental conditions (pH from 7 to 11, [BSA](0) from 1.5 x 10(-5) t o 10(-3) M, [L](0)=[D](0) from 10(-4) to 5 x 10(-4) M). The operational par ameters which can be used to optimize production criteria such as purity, r ecovery and production rate have been discussed. For enantiomeric separatio ns using BSA chiral selector (solution system or enantioselective membrane) , a specific attention has to be taken to both filtration and complexation parameters. (C) 2000 Elsevier Science B.V. All rights reserved.