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Dipeptidyl peptidase III from human erythrocytes
M Abramić1, M Zubanović, L Vitale
1Dept. Organic Chemistry and Biochemistry, Rudjer Bosković Institute, Zagreb.
Biological Chemistry Hoppe-Seyler
|January 1, 1988
Summary
This study details the purification of dipeptidyl peptidase III (DPP III) from human red blood cells. The purified enzyme is a metallo-peptidase with essential SH-groups, showing high affinity for angiotensin III.
Area of Science:
- Biochemistry
- Enzymology
- Human Physiology
Background:
- Dipeptidyl peptidase III (DPP III) is an enzyme found in human erythrocytes cytosol.
- Understanding its properties is crucial for various biochemical and physiological studies.
Purpose of the Study:
- To describe the purification procedure for DPP III from human erythrocytes.
- To characterize the enzyme's properties, substrate specificity, and cofactor requirements.
Main Methods:
- Purification involved sequential chromatography on DEAE-cellulose, hydroxylapatite, and Sephacryl S-200.
- Enzyme activity, inhibition, activation, and substrate kinetics were analyzed.
Main Results:
- A homogeneous DPP III preparation was obtained with 35% yield.
- The enzyme is a monomeric acidic protein (Mr ~82,000, pI ~4.5-4.6), sensitive to freezing and heat (>40°C).
- DPP III is a metallo-peptidase requiring divalent cations and essential SH-groups, activated by Co2+ and Zn2+.
Conclusions:
- DPP III exhibits broad substrate specificity, hydrolyzing peptides and naphthylamides, with Arg-Arg-2-naphthylamide as the best substrate.
- The enzyme shows a high affinity for angiotensin III, suggesting potential roles in peptide hormone metabolism.
- Essential SH-groups and metal ion binding sites are critical for DPP III activity.