Al. Creagh et al., SEPARATION OF AMINO-ACID ENANTIOMERS USING MICELLAR-ENHANCED ULTRAFILTRATION, Biotechnology and bioengineering, 44(6), 1994, pp. 690-698
Micellar-enhanced ultrafiltration (MEUF) is investigated as a large-sc
ale technique for separating amino acid enantiomers. Specifically, L-5
-cholesterol glutamate, a chiral ligand-exchange cosurfactant, is used
together with a nonionic surfactant to form mixed micelles that prefe
rentially bind D-phenylalanine over L-phenylalanine in the presence of
copper(II). Operational selectivities as high as 4.2 are obtained. Po
tentiometric titrations using a water-soluble model compound similar t
o the chiral cosurfactant indicate that the ternary copper complex wit
h phenylalanine has a stereoselectivity for the D enantiomer which is
significantly smaller than that observed in the MEUF system. Thus, the
selectivity of the chiral ligand is sensitive to the ligand's local s
olvent and structural environment. (C) 1994 John Wiley & Sons, Inc.