MONITORING TRIPEPTIDASE ACTIVITY USING CAPILLARY ELECTROPHORESIS - COMPARISON WITH THE NINHYDRIN ASSAY

Capillary electrophoresis (CE) was used to assay the activity of a tri peptidase from a crude extract of Lactococcus lactis subsp. lactis NCD O 712 against the substrate, Gly-Gly-Phe and a comparison with a stand ard ninhydrin assay was made. Standard curves of the substrates and pr oducts showed a significantly variable colorimetric reaction to ninhyd rin making accurate quantification of the tripeptidase problematic. Th e CE assay further demonstrated that the presence of contaminating enz ymes in crude cell-free extracts can cause secondary reactions that ar e not apparent from the ninhydrin assay data. The CE assay was also ab le to generate enzyme kinetics data and monitor, during purification, the presence of co-eluting contaminating activities. The speed and sen sitivity with CE allows routine analysis of the tripeptidase activity without any derivatization normally required for this enzyme.