Nattokinase Doesn't Have a "Purity Percentage" the Way You Think It Does

Most raw materials in our catalog are small molecules with a straightforward HPLC purity specification. Nattokinase is different in a way that catches some buyers off guard: it's a protein enzyme, and purity alone doesn't tell you whether it actually works.

What Nattokinase Actually Is

Nattokinase (NK, CAS 133876-92-3) is a fibrinolytic serine protease of the subtilisin family (EC 3.4.21.62) that occurs naturally during fermentation of soybeans by Bacillus subtilis var. natto — the bacterium used to make the traditional Japanese food natto. As a protein enzyme, it has no fixed small-molecule formula; its polypeptide chain comprises roughly 275 amino acid residues with an approximate molecular weight of 27,728 Da.

Why Purity and Activity Are Separate Numbers

Protein purity is typically confirmed by HPLC and/or Kjeldahl nitrogen determination — this tells you how much of the material is actually nattokinase protein versus other residual material. Fibrinolytic potency, the property that actually matters for the ingredient's function, is measured separately via a fibrin-plate or clot-lysis activity assay expressed in fibrinolytic units (FU/g). A high purity reading does not automatically mean high activity — protein can be present but partially denatured or inactivated, which is exactly why these are reported as two distinct specifications, not one.

What This Means for Comparing Suppliers

• Never compare nattokinase products by mg dose alone — request the FU/g activity rating and calculate total FU delivered per serving, since this is what actually determines a meaningful dose comparison.
• Confirm which activity assay method and reference standard were used — fibrin-plate and clot-lysis methods aren't always directly interchangeable between labs.
• Request the full certificate of analysis showing both purity and activity, and arrange independent third-party verification for large-volume procurement.

Formulation Considerations

Because nattokinase is a protein enzyme, its activity is sensitive to heat, extreme pH, and prolonged exposure to moisture or oxygen. Enteric-coated capsules or tablets are commonly used to protect the enzyme through the acidic stomach environment before release in the intestine, and cool, dry storage with moisture-barrier packaging helps preserve potency through shelf life.

How PathGene Supplies This

Our nattokinase is manufactured through controlled fermentation of selected Bacillus subtilis natto strains, followed by cell separation, ultrafiltration, chromatographic purification, activity standardization, and spray-drying. We provide both purity and FU/g activity data on our certificate of analysis, and can help you calculate accurate per-serving activity for your specific formulation.