Following the lipase catalyzed enantioselective hydrolysis of amino acid esters with capillary electrophoresis using contactless conductivity detection

Abstract

The progress of the enzymatic hydrolysis of racemic mixtures of the enantiomers of the methyl esters of serine and threonine was monitored. This was possible in a reaction vessel of 1.5 mL by direct sampling of volumes in the nanoliter-range directly into an electrophoresis capillary. Contactless conductivity detection was used for quantification as the analytes are not accessible by UV-detection in capillary electrophoresis. Porcine pancreatic lipase and wheat germ lipase both showed a preference for the L-enantiomers of both amino acid esters. The selectivity of the porcine lipase between the two L-esters of the two amino acids was also studied and it was found that the production of L-threonine had priority over L-serine. Chirality 22:331-335, 2010. V V C 2009 Wiley-Liss, Inc.

Capacitively coupled contactless conductivity detection for microseparation techniques – recent developments

“…Schuchert‐Shi and Hauser have shown that CE with C 4 D can also be a useful tool for monitoring enzymatic processes, such as hydrolysis of biomolecules and digestion of proteins 60–62. Products of enzymatic hydrolysis or digestion are often small conductive species that are not directly suitable for conventional optical detection schemes and therefore C 4 D can be used as simple detection method without the need for derivatization.…”

“…Products of enzymatic hydrolysis or digestion are often small conductive species that are not directly suitable for conventional optical detection schemes and therefore C 4 D can be used as simple detection method without the need for derivatization. The system was also applied to characterize the chiral selectivity of several enzymes by measuring the hydrolysis products of racemic mixtures of methyl esters of amino acids 62. Enzymatic oxidation of the UV‐absorbing tyramine using tyramine oxidase was monitored by Urban et al .…”

Chiral electromigration techniques in pharmaceutical and biomedical analysis

“…The kinetics of the enzyme reaction were established and the proof of concept was performed using the known competitive inhibitor pyrrole-2-carboxylic acid. A chiral CE method combined with contactless conductivity detection has been applied to follow the lipase-catalyzed enantioselective hydrolysis of amino acid esters [154]. The crown ether 18C6H4 served as chiral selector in 2 M acetic acid as background electrolyte.…”

Recent advances in applications of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE‐C4D): an update

“…The progress of enzymatic processes such as the hydrolysis of biomolecules and digestion of proteins using CE‐C 4 D weas investigated (Schuchert‐Shi and Hauser, ). The system was used to characterize the chiral selectivity of several enzymes by measuring the hydrolysis products of racemic mixtures of methyl esters of serine and threonine.…”