AN02/DNP-hapten unbinding forces studied by molecular dynamics atomic force microscopy simulations

Unbinding forces of a spin-labeled dinitrophenyl (DNP) hapten from the mono clonal antibody AN0(2) F-ab fragment have been studied by molecular dynamic s atomic force microscopy (AFM) simulations. In our nanosecond simulations, unbinding was enforced by pulling the hapten molecule out of the binding p ocket. From the simulations unbinding forces of the complex have been deter mined as a function of pulling velocity. Considering activated unbinding an d frictional forces, we used a simple model to extrapolate the unbinding fo rces to the millisecond timescale of single molecule AFM unbinding experime nts. For such experiments the simulations suggest an unbinding force of 60 +/- 30 pN. (C) 1999 Elsevier Science B.V. All rights reserved.