Effects of mutations on the C-terminus of protegrin-1: A molecular dynamics simulation study

In this work the effects of the charge of the C-terminus of protegrin-like peptides on activity and toxicity are examined by molecular dynamics simulations. Simulations are done in sodium dodecylsulphate and dodecylphosphocholine micelles, bacterial and mammalian membrane mimics, respectively. Three protegrin mutants are examined and it is found that while the peptides interact in different ways, the peptides all insert into the SDS micelles equally as deep, in agreement with their equal activities as determined by previous experimental work. There are clear differences in the interactions with the DPC micelles and it is demonstrated that simulations with DPC micelles can predict levels of toxicity of such peptides. We also see that removing the positive charge from the sequence of protegrin-1 does not have positive effects on the resulting peptide's toxicity, but that replacing the positive charge with a negative charge reduces the toxicity.