Measurement of active constitutive L-pyrrolidonyl-peptidase from the genera Streptococcus and Enterococcus

In the family Streptococceae the ability to measure L-pyrrolidonyl-peptidase is limited to Lancefield group D Enterococcus and group A Streptococcus pyogenes. A number of methods exist to assay this enzyme. All measure pyrrolidonyl-peptidase by the ability of the bacterium to cleave L-pyrrolidonyl-beta-naphthylamide to form free beta-naphthylamine and L-pyrrolidone-carboxylic acid. Free beta-naphthylamine is then reacted with N,N-dimethylamino-cinnamaldehyde to form a red color complex. These methods are generally expensive and require a 2-4 h incubation period before results are available. A method, which employs the substrate dried on paper discs and can be easily made, is described herein. It is simple to perform, inexpensive, rapid, and has a long storage life. The results of this constitutive method are equivalent to those obtained using a commercial system.