Before revision:  Ligands with flexible chemical scaffold may remain longer at the protein target if they need to pass through extended conformations upon unbinding, or if they exhibit strong electrostatic and/or van der Waals interactions with the target.
After revision:  Ligands may remain longer at the protein target if they need to pass through extended conformations upon unbinding, or if they exhibit strong electrostatic and/or van der Waals interactions with the target.