Rethinking common solvents in butyrylcholinesterase activity assays

Abstract

• The effect of solvents on enzyme activity is quite diverse. Even two enzymes, which are members of the same family, may have different responses to the same solvent. • Acetone has the highest potential to inhibit the butyrylcholinesterase enzyme. • Butyrylcholinesterase is slightly inhibited by ethanol and methanol, making these solvents comparatively preferable in activity measurement assays. • Owing to their inhibitory potentials, the final concentrations of common solvents in the assay medium must be considered carefully. Cholinesterases are a group of enzymes that prevent the message of the neurotransmitter acetylcholine from being transmitted in an undesirable manner. The primary classes of this family are acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In neurodegenerative disorders, including Alzheimer’s disease (AD) and Parkinson’s disease, the levels of these enzymes are altered. The level of AChE declines in Alzheimer’s disease, while the level of BChE increases or remains unchanged. There have been a number of licenced medications developed to combat the negative health impacts of these disorders. However, synthetic medications have a number of unfavorable side effects. The search for alternative BChE inhibitors in the treatment of AD is also on the rise. Some of the compounds examined are not soluble in water and must be dissolved in organic solvents. However, these organic solvents may have a negative or detrimental influence on enzymes. This study examined the inhibitory effects of acetone, dimethyl sulfoxide (DMSO), acetonitrile, ethanol, and methanol on horse serum BChE (hsBChE). Competitive inhibition was observed with acetone, DMSO and ethanol, non-competitive inhibition was observed with methanol, and acetonitrile exhibited linear mixed-type competitive inhibition. Acetone, DMSO, acetonitrile, ethanol, and methanol had IC 50 values of 707 mM, 1719 mM, 1848 mM, 7741 mM, and 12199 mM, respectively, and K i values of 186 ± 15 mM; 529 ± 35 mM, 725 ± 67 mM, 3281 ± 29 mM, and 22991 ± 6535 mM, respectively. These IC 50 and K i values show that methanol is the best solvent, with almost minimal interaction with hsBChE.