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Purification and characterization of human metallocarboxypeptidase Z
1Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, 10461, USA.
Biochemical and Biophysical Research Communications
|March 19, 1999
Summary
Carboxypeptidase Z (CPZ) is a novel enzyme that processes extracellular peptides. This metallocarboxypeptidase prefers C-terminal Arg residues, suggesting a selective role in protein processing.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Carboxypeptidase Z (CPZ) is a newly identified metallocarboxypeptidase.
- CPZ possesses an N-terminal domain homologous to the Wnt/wingless binding domain of frizzled receptors.
Purpose of the Study:
- To elucidate the enzymatic properties of Carboxypeptidase Z.
- To characterize substrate specificity and kinetic parameters of CPZ.
Main Methods:
- Purification of CPZ using Arg- and heparin-affinity chromatography.
- Enzyme activity assays with various peptide substrates.
- Determination of kinetic parameters (Km) and inhibition profiles.
Main Results:
- CPZ exhibits a neutral pH optimum.
- The enzyme is inhibited by chelating agents and divalent cations (Zn2+, Mn2+, Cd2+, Cu2+, Hg2+).
- CPZ selectively cleaves substrates with C-terminal Arg, preferring an Ala in the penultimate position (Km ~2 mM), and shows no activity on Ile-Arg or Pro-Arg sequences.
Conclusions:
- CPZ demonstrates selective enzymatic activity towards specific peptide sequences.
- These findings suggest a specialized function for CPZ in the processing of extracellular peptides or proteins.