Carboxypeptidase B

Description Unwanted C-terminal basic amino acids — lysine, arginine or ornithine — can block protein sequencing, interfere with peptide map interpretation, and leave charged tails on recombinant proteins and processed peptides. Removing them cleanly and reproducibly with a well-characterized exopeptidase is a routine first step in protein analysis and downstream processing. Carboxypeptidase B from porcine pancreas (EC 3.4.12.3) is a zinc-containing metallocarboxypeptidase that selectively hydrolyzes peptide bonds at the C-terminal basic amino acids lysine, arginine and ornithine: Peptidyl-L-lysine + H2O → Peptide + L-Lysine Also known as protaminase or peptidyl-L-lysine [L-arginine] hydrolase, this Carboxypeptidase B is supplied as a lyophilized powder with a specific activity of approximately 50 U/mg protein and a protein content of approximately 80% (biuret method). The powder dissolves readily in distilled water or dilute buffer and remains stable when stored at -20°C. The molecular weight is 34,300 Da. The enzyme activity is precisely defined: one unit hydrolyzes 1 µmol of hippuryl-L-arginine per minute at 25°C and pH 7.65, and hydrolysis is followed directly by the increase in absorbance at 254 nm. With this clear unit definition and simple spectrophotometric assay, Carboxypeptidase B delivers reproducible C-terminal digestion for protein analysis and processing workflows. Specification Product Name Carboxypeptidase B Synonyms Protaminase; Peptidyl-L-lysine [L-arginine] hydrolase Catalog Number BF-1210200 EC Number 3.4.12.3 Biological Source Porcine pancreas Form Lyophilized powder Specific Activity Approximately 50 U/mg protein Protein Content Approximately 80% (biuret method) Molecular Weight 34,300 Da Solubility Distilled water or dilute buffer Storage -20°C Unit Definition One unit hydrolyzes 1 µmol hippuryl-L-arginine per minute at 25°C, pH 7.65 Assay Method Increase in absorbance at 254 nm during hydrolysis of hippuryl-L-arginine Reference Price $3.00 / mg Features Selective hydrolysis of C-terminal basic amino acids — lysine, arginine and ornithine Zinc-containing metallocarboxypeptidase with a molecular weight of 34,300 Da Convenient lyophilized powder, readily soluble in distilled water or dilute buffer Specific activity of approximately 50 U/mg protein Protein content of approximately 80%, determined by the biuret method Stable when stored at -20°C Well-defined unit: 1 U hydrolyzes 1 µmol hippuryl-L-arginine per minute at 25°C, pH 7.65 Simple activity monitoring at 254 nm, with a hippuric acid extinction coefficient of 0.349 Application Carboxypeptidase B is used in protein analysis and biopharmaceutical processing workflows: Insulin production and processing of insulin analogues Protein C-terminal amino acid determination and sequencing Removal of C-terminal basic amino acids (lysine, arginine) from recombinant proteins and peptides Removal of C-terminal histidine tags from recombinant proteins Antibody charge variant analysis and quality detection of recombinant antibodies Peptide mapping and proteomics sample preparation FAQ What is Carboxypeptidase B? Carboxypeptidase B (EC 3.4.12.3) is a zinc-containing pancreatic exopeptidase that selectively hydrolyzes peptide bonds at the C-terminal basic amino acids lysine, arginine and ornithine. It is also known as protaminase or peptidyl-L-lysine [L-arginine] hydrolase, with a molecular weight of 34,300 Da. What is the source and form of this product? This Carboxypeptidase B is derived from porcine pancreas and supplied as a lyophilized powder. How should Carboxypeptidase B lyophilized powder be stored and reconstituted? Store the lyophilized powder at -20°C. Reconstitute by dissolving in distilled water or a dilute buffer. What is the specific activity and protein content of this Carboxypeptidase B? The specific activity is approximately 50 U/mg protein, with a protein content of approximately 80% as determined by the biuret method. How is Carboxypeptidase B activity defined? One unit of Carboxypeptidase B hydrolyzes 1 µmol of hippuryl-L-arginine per minute at 25°C and pH 7.65. How is Carboxypeptidase B activity measured? Activity is measured by the increase in absorbance at 254 nm resulting from the hydrolysis of hippuryl-L-arginine. The initial linear rate (ΔA254/min) is used together with the hippuric acid extinction coefficient of 0.349 to calculate units per mg enzyme. Which amino acids does Carboxypeptidase B cleave? Carboxypeptidase B selectively hydrolyzes the C-terminal basic amino acids lysine, arginine and ornithine. Example reaction: Peptidyl-L-lysine + H2O → Peptide + L-Lysine. Is Carboxypeptidase B a metalloenzyme? Yes. Carboxypeptidase B is a zinc-containing metalloenzyme (metallocarboxypeptidase); one atom of zinc is required for catalytic activity. For research use only. Not for use in diagnostic or therapeutic procedures.