In addition to the spectra of inhib

In addition to the spectra of inhibition, we observed some other differences between PlcA and the other members of subgroup II, such as a higher isoelectric point (8.6) and a net charge of +1. In fact some authors use the pI values and net charges to differentiate between circular bacteriocins of subgroup I (pI~10 and positively charged) from circular bacteriocins of subgroup II (pI 4 to 7 and uncharged or slightly negative) (9). According to this classification system PlcA should be placed in an intermediate position between subgroups I and II. However, we strongly believe that this peptide should be classified within subgroup II and propose to modify the classification criteria and broaden the pI range for this subgroup to be between 4 to ~9.