Integrative structural and kinetic analysis of the molecular basis for reduced carbamate inhibition in atypical butyrylcholinesterase.

Butyrylcholinesterase (BChE) plays a key role in cholinergic transmission and the metabolism of various drugs, making its regulation a promising therapeutic strategy for several diseases, including Alzheimer's disease. Selective inhibition of BChE helps regulate brain acetylcholine levels. However, genetic polymorphisms in the BCHE gene, particularly the Asp70Gly mutation in atypical BChE, can impact treatment outcomes. This study compares the inhibitory potency of 13 carbamates against atypical and usual BChE. Using molecular docking, quantum chemical cluster calculations, and crystallization of wild-type BChE with the most potent carbamate, we identified key differences in carbamylation mechanisms. Atypical BChE shows a less favorable enzyme-inhibitor complex orientation, lacking the hydrogen bond stabilization of the reactive carbonyl oxygen. Additionally, Asp70 in usual BChE contributes to stabilizing the non-reactive carbamate group, whereas Gly70 in atypical BChE is too distant to form such interactions.