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α-Chymotrypsin from bovine pancreas

(TLCK treated to inactivate residual tryspin activity), Type VII, essentially salt-free, lyophilized powder, ≥40 units/mg protein

CAS Number:
Enzyme Commission number:
EC Number:
MDL number:

Quality Level


Type VII


essentially salt-free, lyophilized powder

specific activity

≥40 units/mg protein

mol wt

25 kDa


1 mM HCl: soluble 10 mg/mL, clear

UniProt accession no.

storage temp.


Gene Information

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α-Chymotrypsin from Sigma has been used to determine the crystal structures of two homologous inhibitors (pars intercerebralis major peptide-C and pars intercerebralis major peptide-D2v) from the insect Locusta migratoria by forming a complex with the enzyme.


10, 25, 100 mg in glass bottle

Biochem/physiol Actions

α-Chymotrypsin is a serine peptidase and has 241 amino acid residues contained in three polypeptide chains (A chain-13 residues, B chain-131 residues, and C chain-97 residues) linked by disulfide bridges. Molecular weight of this enzyme is found to be 25 kDa. Its pI is 8.75. It selectively hydrolyzes peptide bonds on the C-terminal side of tyrosine, phenylalanine, tryptophan, and leucine. Ca2+ activates and stabilizes the enzyme. The enzyme is inhibited by diisopropyl fluorophosphate (DFP), phenylmethanesulfonyl fluoride (PMSF), N-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), chymostatin, aprotinin, α1-antitrypsin, α2-macroglobulin, 10 mM Cu2+ and Hg2+.
A serine protease that hydrolyzes peptide bonds with aromatic or large hydrophobic side chains (Tyr, Trp, Phe, Met, Leu) on the carboxyl end of the bond.

Unit Definition

One unit will hydrolyze 1.0 μmole of BTEE per min at pH 7.8 at 25 °C.

Preparation Note

TLCK treatment inactivates trypsin which may be present in chymotrypsin, without affecting the chymotrypsin activity.

Analysis Note

Protein determined by A1%/280

Other Notes

Signal Word


Hazard Classifications

Acute Tox. 4 Oral - Aquatic Acute 1 - Eye Irrit. 2 - Resp. Sens. 1 - Skin Irrit. 2 - STOT SE 3

Target Organs

Respiratory system

Storage Class Code

11 - Combustible Solids

WGK Germany


Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves

Certificate of Analysis

Certificate of Origin

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  4. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  5. What is the molecular weight of alpha-chymotrypsin from bovine pancreas (Product No. C3142)?

    The molecular weight of alpha chymotrypsin, reported in the literature, is approximately 25 kDa.This information and the basic structure description of the enzyme can be found on our product information sheet (under Documents, above) at our website.

  6. How do you recommend preparing a solution of Product No. C3142?

    It is recommended to reconstitute Product No. C3142 in 1 mM hydrochloric acid containing 2 mM calcium chloride. The calcium functions as both a stabilizer (and possibly an activator) of the enzyme.

  7. How can solutions of alpha-chymotrypsin (Product No. C3142) be stored?

    Stock solutions prepared in 1 mM HCl, containing 2 mM calcium chloride, can be stored at -20 ° for about one week.

  8. What is the pH optimum for the enzyme, Product No. C3142?

    The pH optimum for alpha-chymotrypsin is between pH 7.5-8.5. Please see the following reference: Wilcox, P.E., Chymotrypsingogens-chymotrypsins, Methods in Enzymology, 19, 64-80 (1970).

  9. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

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The crystal structures of two homologous inhibitors (PMP-C and PMP-D2v) from the insect Locusta migratoria have been determined in complex with bovine alpha-chymotrypsin at 2.1- and 3.0-A resolution, respectively. PMP-C is a potent bovine alpha-chymotrypsin inhibitor whereas native PMP-D2 is...
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Analytical Enzyme Chymotrypsin: Chymotrypsin is produced in the acinar cells of the pancreas as the inactive precursor, chymotrypsinogen.


Procedure for Enzymatic Assay of α-Chymotrypsin (EC

Follow our procedure for the determination of a chymotrypsin activity. This enzymatic assay of alpha chymotrypsin guides you through the entire process and necessary calculations.

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