Quick Definition
What is Fatty Acid Free BSA?: Fatty acid free BSA (BSA FAF) is bovine serum albumin processed to remove bound fatty acids, lipids and steroid hormones by charcoal treatment or solvent extraction. Standard BSA contains 0.5–2 moles of fatty acids per mole of albumin — sufficient to activate fatty acid receptors (PPAR, FFAR) and interfere with IVF, lipid metabolism research and DMPK protein binding measurements.
Why fatty acid contamination matters in BSA
Albumin has multiple fatty acid binding sites (FA1–FA7). When occupied by endogenous fatty acids, two problems arise: (1) fatty acid receptors on cells (PPAR-α/γ/δ, FFAR1-4) are activated non-specifically creating background; (2) albumin drug binding sites are reduced, artificially lowering apparent drug-albumin affinity in protein binding assays.
FAF-BSA in DMPK fu,mic assays
BSA FAF at 0.5–2% is added to microsomal metabolic stability assays to reduce non-specific membrane binding of lipophilic compounds, improving IVIVE accuracy. BSA FAF specifically is used — not standard BSA — because it does not introduce competing fatty acids at BSA drug binding sites.
Key Facts
- Standard BSA: ~0.5–2 mol fatty acid/mol albumin — predominantly long-chain fatty acids (palmitate, oleate, stearate)
- FAF-BSA: <0.005% fatty acids — confirmed by colorimetric or GC-MS fatty acid assay per lot
- Used in IVF medium at 3–6 mg/mL — standard BSA fatty acids impair sperm motility, capacitation and oocyte quality
- Used in PPAR, LXR, FXR nuclear receptor assays — fatty acids in standard BSA activate these receptors non-specifically
- Used in DMPK fu,mic correction — BSA FAF is the industry standard for removing microsomal lipid partitioning of drugs
- Used as serum-free medium supplement when defined lipid content is required
Further Reading
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