Activity of different proteases in a complex mixture and in vitro study of their reciprocal interferences by micellar electrokinetic chromatography

The presence of Pseudomonas aeruginosa elastase and, possibly, of other metalloelastases in complex biological fluids may mask the activities of serine proteinases (human neutrophil elastase and cathepsin G, Cat G) when using synthetic p-nitroanilide peptides as substrates. Using micellar electrokinetic chromatography we investigated the reciprocal interference that these proteinases, present as a mixture in a representative model of in vitro lung secretions, could exert on each other. The results reported here show that, although different proteinases may be present in the mixture, accurate assay of each can be achieved by incubating these enzymes with highly specific inhibitors that, in turn, inhibit a single, well-defined proteolytic activity. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 302–307, 2000