Before revision:  The simulations show that heparin polyanionic chains can bind at long, mostly positively charged patches on the spike, preventing the binding of host cell heparan sulphate proteoglycans to the spike. Heparin can mask both the S1/S2 basic motif, thereby inhibiting furin cleavage and the formation of the prefusion conformation, and the basic residues of the receptor binding domain (RBD), thus acting on the hinge region responsible for the motion of the RBD between inactive closed and active open conformations of the spike.
After revision:  The simulations show that heparin polyanionic chains can bind at long, mostly positively charged patches on the spike, and thereby mask the basic residues of the receptor binding domain and the basic S1/S2 basic motif, thereby inhibiting furin cleavage and the formation of the prefusion conformation, and the basic residues of the receptor binding domain (RBD), thus acting on the hinge region responsible for the motion of the RBD between inactive closed and active open conformations of the spike.