A Single Molecule Study of Enzyme Inhibitor Interactions

Abstract

Recently developed microscopic models by Dudko et al. were used to estimate the apparent kinetic and thermodynamic parameters in a single molecule force spectroscopy study of the carbonic anhydrase enzyme and a sulfonamide inhibitor. The most probable rupture force for the enzyme-inhibitor interaction demonstrates a nonlinear dependency on the log-loading rate. Estimates for the kinetic and thermodynamic parameters were obtained by fitting the nonlinear dependency to linear cubic potential and cusp potential models and compared to the Bell-Evans model. The reliability of the estimated parameters was verified by modeling the experimental rupture force distributions by the theoretically predicted distributions at rupture. We also report that an increase in the inhibitor tether length has a significant effect on the apparent kinetic and thermodynamic parameters while extending the length of the linkers which attach the enzyme to the surface has a minimal effect.