K4519 Sigma


lyophilized powder

Synonym: KerA, Keratinase from Bacillus licheniformis, Keratinolytic protease


recombinant   expressed in E. coli BL21
form   lyophilized powder
mol wt   mol wt ~39 kDa
pH-range   5.5 - 12.5 (optimum activity is seen at pH 12.5)
pI    8.73
storage temp.   −20°C


Other Notes

This enzyme contains a C-terminus 6-Histidine tag.

Preparation Note

The enzyme can be solubilized at 0.5-1.0 mg/mL in either sterile water or phosphate buffer. The best activity is seen with freshly prepared solutions. However, single-use aliquots of Keratinase solutions can be stored at -20° C.


Keratin. Keratinases have also been used for the degradation of prion and prion-like proteins.

Unit Definition

One unit of enzyme is able to hydrolyze casein resulting in an absorbance value as the Folin-Ciocalteau reagent equivalent to 1 umole (181μg) of tyrosine per minute at pH 7.5 at 37 °C.

General description

Keratinase is a non-specific serine protease that cleaves non-terminal peptide bonds.

Physical properties

Keratinase is activated by 0.10% SDS, 1.0% CTAB, and EDTA. Keratinase is partially inhibited by Tween®20, DMSO, isopropanol, methanol, and ethanol.

Legal Information

TWEEN is a registered trademark of Croda International PLC

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