According to the referenced paper, VR has an AChE inhibition reaction rate constant almost 4 times that of VX. Interestingly, its reaction rate constant for aging of the enzyme is less than that of VX, despite the fact that, as acknowledged by the authors of the paper, aging tends to occur faster when the leaving group during aging is a branched alkoxy group. Finally, VR-inhibited AChE is also more prone to spontaneous reactivation compared to AChE inhibited by VX. What is the reason for these differences in reaction kinetics for the interactions of these two agents with AChE?
Worek, F., Thiermann, H., Szinicz, L., & Eyer, P. (2004). Kinetic analysis of interactions between human acetylcholinesterase, structurally different organophosphorus compounds and oximes. Biochemical Pharmacology, 68(11), 2237–2248. doi:10.1016/j.bcp.2004.07.038