Acetate¶
Definition¶
Acetate (CH₃COO⁻) is a counter-ion used in peptide salts, typically obtained by exchanging the TFA counter-ion through ion exchange chromatography during manufacturing.
Overview¶
Acetate is the preferred counter-ion for peptides used in cell-based assays and biological experiments. It is biologically more compatible than TFA and has lower cytotoxicity.
Technical Explanation¶
Properties of Acetate Salt: - Chemical formula: CH₃COO⁻ (acetate anion) - Molecular weight contribution: ~59 Da per acetate molecule - Peptide content: Higher than TFA salt (acetate is lighter and fewer molecules needed) - Less hygroscopic than TFA salt
Advantages Over TFA: - Lower cytotoxicity - No interference with ion channel studies - More physiological compatibility - Higher peptide content per milligram of solid
Conversion from TFA: TFA salt → Ion exchange chromatography → Acetate salt The exchange efficiency is confirmed by fluoride ion analysis or NMR.
Importance in Peptide Documentation¶
Product documentation should specify whether the peptide is TFA or acetate salt. This affects assay calculation, solubility recommendations, and application suitability.
Related Terms¶
Frequently Asked Questions¶
Q: Is acetate form always better than TFA? A: For cell-based assays and in vivo work, acetate is generally preferred. For routine analytical work or bacterial expression studies, TFA is often acceptable. The choice depends on the specific application.
Q: How do I know if my peptide is acetate or TFA salt? A: Check the COA or TDS — the counter-ion content (% w/w) and type should be specified. If not listed, contact the supplier for clarification.