Before revision:  This concentration is identified as an onset of crowding beyond which it is impossible, even in principle, to extract information about hydrodynamic size of the peptide-surfactant complex  ]  .
After revision:  This concentration is identified as an onset of crowding beyond which it is impossible, even in principle, to extract information about hydrodynamic size of the peptide-surfactant complex from diffusion measurements, experiments must be carried out at or below ] .