The inner membrane permeability of the peptides.

ONPG was cleaved by cytoplasmic β-galactosidase of E. coli UB1005 treated by peptides R-FV-I16 and ME26 at 1 and 1/2 × MIC, and hydrolysate (ONP) was measured spectroscopically at absorbance of 420 nm as a function of time.