... speci c substrate to selectively measure activity inbiological samples. Here we describe the development of such a substrate based on analysis of PrtA cleavagesite specificity, and kinetic characterization ... knownspecificity. A simple probability analysis of amino acidfrequencies (not shown) indicated a slightly higherfrequency of Leu and Val at position P2¢, which is inaccordance with the presence of ... Hungarian Academy of Sciences, Budapest, Hungary4 Biotechnology Research Group, Hungarian Academy of Sciences, Budapest, Hungary Of the various enzymes that microorganisms secretefor defence as...