Interaction of trifluoroacetates with acetylcholinesterase
Interaction of trifluoroacetates with acetylcholinesterase
There exists a substance called TMTFA, or 3-(N,N,N -Trimethylammonio)-2,2,2-trifluoroacetophenone. It is known for being able to inhibit acetylcholinesterase at femtomolar concentrations. The TMTFA-AChE adduct resembles the tetrahedral transition state through which the hydrolysis of acetylcholine by the enzyme normally proceeds, and this adduct is stabilized by the electron-withdrawing trifluoromethyl group present in the TMTFA molecule. This inhibition is reversible.
While there have been studies regarding trifluoroacetophenones and their interactions with AChE, I haven't been able to find studies exploring the interactions between AChE and trifluoroacetates, such as 3-(N,N,N -trimethylammonio)phenyl trifluoroacetate or 2,2,2-trifluoroacetylcholine. Would these, and other, esters of trifluoroacetic acid inhibit AChE or be hydrolyzed normally? If it's the former, then what are the typical inhibitory concentrations of such esters? What is the shape of the adduct of the ester with AChE? How long would they remain bound to the enzyme? Have any studies been done regarding the bioactivity of such esters?
References
- Nair, H. K.; Seravalli, J.; Arbuckle, T.; Quinn, D. M. Molecular Recognition in Acetylcholinesterase Catalysis: Free-Energy Correlations for Substrate Turnover and Inhibition by Trifluoro Ketone Transition-State Analogs. Biochemistry 1994 , 33(28) , 8566–8576. DOI: 10.1021/bi00194a023.
- Harel, M.; Quinn, D. M.; Nair, H. K.; Silman, I.; Sussman, J. L. The X-Ray Structure of a Transition State Analog Complex Reveals the Molecular Origins of the Catalytic Power and Substrate Specificity of Acetylcholinesterase. J. Am. Chem. Soc. 1996 , 118(10) , 2340–2346. DOI: 10.1021/ja952232h.
K2-Think
The interaction of trifluoroacetate esters with acetylcholinesterase (AChE) can be analyzed based on their structural similarity to AChE substrates and transition state analogs (TSAs), along with the electronic effects of the trifluoromethyl (CF₃) group. Here's a structured breakdown:
1. Hydrolysis vs. Inhibition
AChE primarily hydrolyzes alkyl esters like acetylcholine (ACh), where the...
GPT-5
Short answer
- Trifluoromethyl ketones such as TMTFA inhibit AChE because they form a long‑lived, reversible hemiketal that mimics the tetrahedral transition state and is strongly stabilized by the CF3 group and the oxyanion hole.
- Simple trifluoroacetate esters (including 2,2,2‑trifluoroacetylcholine and quaternary‑ammonium aryl trifluoroacetates) do not do that. They react with AChE exactly as ...
o3
Short answer
• Ordinary trifluoroacetates are not potent inhibitors of acetylcholinesterase (AChE); they are turned over as normal–or even slightly faster than normal–substrates.
• Ki / IC50 values therefore lie in the millimolar range (≈ the Km of a substrate), i.e. 10^6- to 10^9-fold higher than the femtomolar Ki of a trifluoromethyl-ketone such as TMTFA.
• The covalent species that is ...
o4 mini
Below is a sketch of why trifluoroacetate esters of the type you ask about would almost certainly behave as ordinary AChE substrates (albeit somewhat faster ones) rather than femtomolar inhibitors like the trifluoromethyl ketones (TMTF-ketones). In fact, to the best of the chemical-biology literature, no one has ever reported a stable, long-lived AChE adduct arising from a TFA-ester (only the ...
Claude 3.7 Sonnet
Interaction of Trifluoroacetates with Acetylcholinesterase
Your question explores an interesting potential interaction between trifluoroacetates and acetylcholinesterase (AChE), comparing them to the known potent inhibitor TMTFA. Let me address your specific questions based on mechanistic principles and the available literature.
Mechanistic Differences: TMTFA vs. Trifluoroacetates
The key ...
o3 Pro
Short answer
No. Esters of trifluoroacetic acid are not nanomolar or femtomolar inhibitors of acetylcholinesterase (AChE); they are simply (and usually very good) substrates. They are turned over in the normal two-step acyl-enzyme mechanism, the acyl-enzyme lifetime is in the µs–ms range, and they leave the active site after one catalytic cycle. Kinetic constants that have been measured for 2...
DeepSeek R1
First, I need to rec...
Claude Opus 4
This is an excellent question about the potential interactions between trifluoroacetate esters and acetylcholinesterase (AChE). Let me address your questions systematically.
Would trifluoroacetate esters inhibit AChE or be hydrolyzed normally?
Based on the chemical principles and what we know about AChE mechanism, trifluoroacetate esters would likely **inhibit AChE rather than be hydrolyzed n...
Gemini 2.5 Pro
This is an excellent and insightful question. You've correctly identified the key features of the TMTFA inhibitor and are asking the logical next question: what happens if we change the ketone to an ester? This is the exact kind of thinking that drives drug design and mechanistic enzymology.
Let's break down the answer by first comparing the mechanism of the ketone (TMTFA) with what we would expe...
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