Bovine serum albumin

CAS 9048-46-8

CAS: 9048-46-8
Grades: New Zealand origin, Australian origin, standard grade
Special grades: Protease-free, IgG-free and similar on request

Catch-Chem lists BSA by origin so an IVD review can name New Zealand or Australia, plus a standard grade for routine blocking. Origin does not imply Fraction V, protease-free, fatty-acid free, IgG-free or low endotoxin; name those on the inquiry. BSA is albumin, not serum.

What it is

Bovine serum albumin is a single-chain plasma protein of about 66.5 kDa with 17 disulfide bonds. It carries fatty acids, hormones and small molecules in blood, is highly soluble and stable, and adsorbs readily to plastic and membranes, which is why it works as a blocker and carrier.

Where it is used

Blocking in ELISA, Western blot and IHC, typically 1–5% (w/v).
Carrier and stabilizer for enzymes and antibodies, often 0.1–1 mg/mL, for example in restriction-enzyme buffers.
Standard protein for Bradford and BCA assays.
Supplement in serum-free media and IVD calibrator or diluent matrices.

Handling tips

Sprinkle the powder onto the liquid surface and let it dissolve with gentle swirling; vortexing causes foaming and denaturation.
Store powder at 2–8 °C, sealed and dry. Filter-sterilize solutions and refrigerate or freeze in aliquots.
Some antibodies cross-react with bovine IgG in standard BSA; IgG-free grades address that.

What to specify when ordering

Origin: New Zealand, Australia or standard. Read how the grades are split.
Special tests: protease-free, fatty-acid free, IgG-free, low endotoxin.
Pack size. Casein and other blockers are on the blocking page.

Properties and storage

Formula: —
Molecular weight: about 66.5 kDa
Appearance: White to pale yellow lyophilized powder
Solubility: Soluble in water and buffers; swirl gently, avoid foaming
Storage: 2–8 °C, dry, sealed
Typical packs: 10 g, 50 g, 100 g, 1 kg

Typical literature values. The batch COA / SDS governs.

Before you inquire

Is New Zealand BSA protease-free?

Only if that test is requested on the inquiry and shown on the certificate.

Is BSA the same as FBS?

No. BSA is purified albumin; FBS is whole serum.

Should I block with BSA or milk for phospho-antibodies?

BSA is usually preferred, because milk contains casein, a phosphoprotein, and endogenous biotin that can raise background.

Pack sizes and catalogue numbers