Substrate selectivity, peptide copper complexes

More recently, the activity of serum peptidases was investigated by capillary electrophoresis with electrochemical detection [60]. Increased peptidase activity in blood is characteristic of a number of disease states. In this application, leu-enkephalin was used as a model substrate. Leu-enkephalin and its metabolites were separated and detected with CEEC following on-capillary copper complex-ation. By incorporating copper in the run buffer, peptides were complexed directly on-capillary [61]. The copper(ll) complexes could then be detected at +700 mV by oxidation to Cu(lll). The method shows good selectivity for peptides over amino acids. This method was used to monitor the metabohsm of leu-enkephalin by enzymes present in a serum sample (Eigure 10). 

---