Scientific Reference
Acetic Acid Water
Evidence profile: Component evidence only — this formulation has not itself been studied
Acetic acid water is water containing a little acetic acid, used in the laboratory as a mildly acidic diluent rather than as a research compound. Acetic acid, also called ethanoic acid, is the weak carboxylic acid that gives vinegar its sourness; the CAS number on this page refers to the acid itself. At low concentration it brings the pH of water into the acidic range without the extremes of a strong mineral acid. Some peptides, especially strongly basic or aggregation-prone sequences, dissolve poorly in neutral water, and a dilute acid is one of the standard alternatives. Its interest here is purely practical: it has no pharmacological role in the work it accompanies.
Mechanism of Action
Acetic acid has a pKa of about 4.76, so in water only a small fraction of its molecules dissociate into acetate and hydrogen ions. The resulting pH depends on concentration but stays well above that of a strong acid at the same concentration. Peptides carry ionisable groups: the N-terminal amine, the C-terminal carboxyl and side chains such as lysine, arginine, histidine, aspartate and glutamate. Below a peptide's isoelectric point its net charge is positive, and like charges on neighbouring molecules repel one another, which tends to reduce aggregation and precipitation. That is the physical-chemistry reason a dilute acid can dissolve sequences that stay cloudy in neutral water.
Molecular Information
- Type: Solvent (aqueous acidic solution)
- Molecular weight: 60.05 g/mol
- Molecular formula: C2H4O2
- CAS: 64-19-7
Published Research
Sweet and sour synergy: exploring the antibacterial and antibiofilm activity of acetic acid and vinegar combined with medical-grade honeys
Harrison F et al. · Microbiology (Reading, England) · 2023 · Review · Evidence for Acetic acid
PMID 37435775 — View on PubMed