  The extent of coupling between the folding of a protein and its binding to a
substrate varies from protein to protein. Some proteins have highly structured
native states in solution, while others are natively disordered and only fold
fully upon binding. In this Letter, we use Monte Carlo simulations to
investigate how disordered polymer chains grafted around a binding site affect
the folding and binding of three model proteins. The protein that approaches
the substrate fully folded is more hindered during the binding process than
those whose folding and binding are cooperative. The polymer chains act as
localized crowding agents and can select correctly folded and bound
configurations in favor of non-specifically adsorbed states. The free energy
change for forming all intra-protein and protein-substrate contacts can depend
non-monotonically on the polymer length.
