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Cystatin B/CSTB Protein, Human (His)

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Cystatin B (CSTB) Protein is a member of the cystatin family. Cystatin B/CSTB Protein, Human (His) is the recombinant human-derived Cystatin B/CSTB protein, expressed by E. coli , with N-His labeled tag.

For research use only. We do not sell to patients.
  • Species: Human
  • Source: E. coli
  • Storage:
    Stored at -20°C for 2 years from date of receipt. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.
  • Experimental Validation Results for Cystatin B/CSTB Protein, Human (His)
  • Cystatin B/CSTB Protein, Human (His) Product Image
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To place orders, for customer services and technical support, please contact:

609-228-6898
[email protected] [email protected]
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  • Biological Activity
  • Technical Parameters
  • Product Properties
  • Documentation
  • Help & FAQs
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Biological Activity

Description

Cystatin B (CSTB) Protein is a member of the cystatin family. Cystatin B/CSTB Protein, Human (His) is the recombinant human-derived Cystatin B/CSTB protein, expressed by E. coli , with N-His labeled tag.

Background

Cystatin B/CSTB Protein functions as an intracellular thiol protease inhibitor. Cystatin B/CSTB protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. Cystatin B/CSTB protein is thought to play a role in protecting against the proteases leaking from lysosomes. Evidence indicates that mutations in Cystatin B/CSTB gene are responsible for the primary defects in patients with progressive myoclonic epilepsy (EPM1). The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and kininogens.

Verified Bioactivity

Measured by its ability to inhibit papain cleavage of a fluorogenic peptide substrate Z-FR-AMC. The IC50 value is < 30 nM. (Activation description: The proenzyme needs to be activated in reducing buffer for an activated form.)

MCE Validation Data

  • Purity - SDS-PAGE

    Purity - SDS-PAGE

    ≥ 95%, as determined by reducing SDS-PAGE.

Technical Parameters

  • Species Human
  • Source E. coli
  • Tag N-His
  • Accession

    Q76LA1 (M2-F98)

  • Gene ID
    1476  [NCBI]
  • Molecular Construction
    • N-term
    • His
    • CSTB (M2-F98)
      Accession # Q76LA1
    • C-term
  • Protein Length

    Full Length

  • Synonyms

    CSTB; Cystatin B (Stefin B); Prev. STFB; CPI-B; Prev. EPM1; Epididymis Secretory Sperm Binding Protein; CST6; Epilepsy, Progressive Myoclonic 1; Cystatin-B; Stefin B; PME; EPM1A; Liver Thiol Proteinase Inhibitor; ULD; Cystatin B; Stefin-B

  • AA Sequence

    MCGAPSATQPATAETQHIADQVRSQLEEKENKKFPVFKAVSFKSQVVAGTNYFIKVHVGDEDFVHLRVFQSLPHENKPLTLSNYQTNKAKHDELTYF

  • Molecular Weight

    Approximately 15 kDa, based on SDS-PAGE under reducing conditions.

  • Purity

    ≥ 95%, as determined by reducing SDS-PAGE.

Product Properties

Appearance

Lyophilized powder.

Formulation

1.Lyophilized from a 0.22 μm filtered solution of 50 mM Tris, 50 mM NaCl, pH 8.0, 5% trehalose, 5% mannitol, 0.01% Tween 80.
2.Lyophilized from a 0.22 μm filtered solution of 50 mM Tris-HCl, 300 mM NaCl, pH 8.0.
Please refer to the lot-specific COA for specific buffer information.
Note: For SPR assay, please replace the buffer. Primary amine components (e.g., Tris, imidazole) can affect protein-coupled chips.

Endotoxin Level

<1 EU/μg, determined by LAL method.

Reconstitution

It is not recommended to reconstitute to a concentration less than 100 μg/mL in ddH2O. For long term storage it is recommended to add a carrier protein (0.1% BSA, 5% HSA, 10% FBS or 5% Trehalose).

Storage & Stability

Stored at -20°C for 2 years from date of receipt. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Shipping

Room temperature in continental US; may vary elsewhere.

Calculators

Reconstitution Calculator

Volume (to add to vial) = Mass (in vial) ÷ Desired Reconstitution Concentration

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Dilution Calculator

Concentration (start) × Volume (start) = Concentration (final) × Volume (final)

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The Specific Activity Calculator Equation
  • Specific Activity (Unit/mg)
  • Biological Activity (ED50)

Specific Activity (Unit/mg) = 106 ÷ Biological Activity (ED50)

Specific Activity (Unit/mg) Specific Activity (Unit/mg)
Unit/mg
= 106 ÷
Biological Activity (ED50) Biological Activity (ED50)
106 ÷
ng/mL
MOQ
Minimum order quantity
100 mg

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Measured by its ability to inhibit anti-CD3-induced proliferation of stimulated CTLL-2 mouse cytotoxic T cells. The ED50 this effect is 0.8023 μg/ml, corresponding to a specific activity is 1246.42 units/mg.

Assay Types
  • 1/16

    MedChemExpress Validation
     ≥ 95%, as determined by reducing SDS-PAGE.

  • Cystatin B/CSTB Protein, Human (His) Product Image
    1/16
  • Experimental Validation Results for Cystatin B/CSTB Protein, Human (His)
  • Cystatin B/CSTB Protein, Human (His) Product Image