Expression of binding energy on an antibody reaction coordinate

In this paper, we report the investigation of how the catalytic antibody 17 E8 uses remote binding energy along the catalyzed hydrolytic reaction coord inate. With the use of alternative substrate analogues, we find that 17E8 c an use free energy from binding interactions between the substrate side cha in and antibody recognition pocket to equally stabilize the transition stat e and the Michaelis complex. In these cases, the interactions are not used to increase k(cat). We have also identified substrates for which the intera ctions are used to preferentially stabilize the transition state over the M ichaelis complex. In these cases, the interactions are used to increase k(c at). Mechanistic studies support the idea that the differences in the subst rates' kinetic activities results from differences in the expression of sid e-chain-pocket binding energy along the reaction coordinates. These results suggest that generating catalytic antibodies to transition-state analogues may be limited because the selective use of remote binding interactions ca nnot be programmed into transition-state analogues.