Recombinant Enterokinase, Mass Spec Grade

• Cat.No.: Enterokinase-56

Specification

• Description: Enterokinase (EK) is a highly specific serine protease that recognizes the amino acid sequence Asp-Asp-Asp-Asp-Lys and cleaves after the lysine residue. It is commonly used to remove fusion tags from recombinant proteins without affecting native sequences. EK is suitable for use in pharmaceutical, diagnostic, and structural biology applications due to its high specificity, efficiency, and activity under mild conditions. This product is a highly pure, specific, and active bovine enterokinase mutant produced via recombinant expression in E. coli.
• Form: Lyophilized powder containing 0.39 mg Tris-HCl and 0.01 mg CaCl2.
• Bio-activity: 16,000 unit/mg
• Molecular Mass: 26.2 kDa
• Purity: Impurity protein peaks measured by LC at 280 nm; rEnterokinase peak intensity >98.5 %.
• Storage: At -20 centigrade freezer
• Reconstitution: Dissolve in 50 μL of ultra-pure water to 1 μg/μL
• CAS No.: 70023-02-8
• Shelf life: 12 months at -20 centigrade freezer
• Usage Notes: Usage Instructions: Recommended buffer system: 50 mM Tris or HEPES buffer, pH 6.0-8.5. Fusion protein digestion: Use a 1:500 or 1:1000 enzyme-to-protein ratio; maintain protein concentration at 0.2-0.5 μg/μL; incubate at 4-25 centigrade for 12 hours. Note: >2 M urea, >250 mM NaCl, >20 mM β-ME, >0.1 % SDS, >50 mM imidazole, or PBS may impair enzyme activity.
• Specificity: Substrate Gly-Asp-Asp-Asp-Asp-Lys-β-naphthylamide (GD4K-na) was digested with enterokinase at 4 centigrade for 20 hours; ESI-MS/MS analysis confirmed 100 % specificity.
• Unit Definition: One unit is defined as the amount of enzyme in 1 μg enterokinase (diluted 20×) that reacts with 0.012 μmol GD4K-na peptide under the following conditions: 50 μL 50 mM Tris (pH 8.0), incubated at 4 centigrade for 20 hours, analyzed by LC-MS.
• LC-MS/MS Analysis: 25 μg GD4K-na peptide incubated with 0.05 μg enterokinase in 50 μL 50 mM Tris for 20 hours; specificity confirmed by ESI QE HF mass spectrometry.
• pH Range: Optimal pH Range: pH 6.0-8.5