ENANTIOMERIC SEPARATION OF TRYPTOPHAN BY ULTRAFILTRATION USING THE BSA SOLUTION SYSTEM

The optical resolution of racemic tryptophan was performed by ultrafil tration using the BSA solution system. The pH of the feed solution had a strong influence on the complexation constants between BSA and tryp tophan, especially for L-tryptophan. The complexation constant for L-t ryptophan reached a maximum value at pH 9 (K-L = 110,000), varying by 2 orders of magnitude in the range from pH 6 (K-L = 1000) to pH 11 (K- L = 21,000). Smaller variations of the complexation constant of D-tryp tophan were observed. Based on these data, the recovery and the purity of the permeate were optimized by a proper control of the physicochem ical parameters of the feed solution (essentially pH and initial conce ntrations). In one stage, 91% purity with a 89% recovery of D-tryptoph an has been easily obtained with a high permeation rate (6.3 x 10(-4) mol.m(-2).s(-1) at 1.5 bar).