Quantification of the effectiveness of indolicidin and protegrin-4 by means of analysis of kinetic parameters

Abstract

Sequences of indolicidin and protegrin-4 were taken from the Data Bank of Nebraska University, USA and were chemically synthesized without terminal amide and nor N-terminal acetylation. Indolicidin and protegrin-4, consisting of 13 and 18-residue peptides, respectively with 95% of purity. These peptides were tested to estimate their antimicrobial effectiveness against Salmonella sp., Escherichia coli and Staphylococcus epidermidis using 1 x 10⁶ cells/mL. Their effectiveness was determined by means of Colony Forming Units (CFUs) after 1 hour of exposition at 20, 50 and 100 μM of every peptide and then were estimated the specific death rate (Kd) and specific apparent growth rate (μnet). These kinetic parameters were used for modelling the extinction time and growth rate of the strains bacteria tested in vitro conditions and the highest activity of both peptides was observed against E. coli in every concentration tested. We conclude that modified indolicidin and protegrin-4 have high antimicrobial activity almost similar to those of previous reports.