Berdal B P, Olsvik O
Acta Pathol Microbiol Immunol Scand B. 1983 Feb;91(1):89-91. doi: 10.1111/j.1699-0463.1983.tb00014.x.
Legionella strains produce extracellular proteases. One method to demonstrate these is through the activity of broth culture filtrates on para-nitroanilide (pNA)-derivatized peptides. Previously, this method has comprised a 100-times concentration of the filtrates, in order to bring the protease activity, as measured by the liberation of free pNA from hydrolysed peptides, up to easily recordable values. By introducing a diazotation step, the sensitivity of the test has been increased sufficiently to omit the time-consuming concentration procedure. Accordingly, the analysis of extracellular Legionella proteases by pNA-derivatized peptides has become rapid and straight-forward.
