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Purification and characterization of human microsomal dipeptidase
Journal of Biochemistry
|June 1, 1989
Summary
Human microsomal dipeptidase (MDP) was purified and found to be a glycoprotein. This enzyme catalyzes the hydrolysis of S-cysteinyl-glycine adducts and leukotriene D4, suggesting a role in glutathione and leukotriene metabolism.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Human microsomal dipeptidase (MDP), also known as dehydropeptidase-I, is an enzyme found in kidney membranes.
- Its precise physiological role, particularly in the metabolism of specific substrates, requires further elucidation.
Purpose of the Study:
- To purify and characterize human microsomal dipeptidase (MDP).
- To investigate the substrate specificity and potential metabolic roles of human MDP.
Main Methods:
- Solubilization of MDP from kidney membrane fractions using octyl-beta-D-glucoside.
- Purification via ion exchange and affinity chromatography on cilastatin-immobilized Sepharose.
- Characterization using SDS-polyacrylamide gel electrophoresis, endoglycosidase F treatment, and Con A-Sepharose binding.
Main Results:
- Purified human MDP was homogeneous, with an estimated molecular weight of 130 kDa (homodimer) that reduced to 42 kDa after endoglycosidase F treatment, indicating it is a glycoprotein.
- MDP demonstrated catalytic activity in hydrolyzing S-cysteinyl-glycine adducts and converting leukotriene D4 to leukotriene E4.
- Binding to Con A-Sepharose confirmed the glycoprotein nature of human MDP.
Conclusions:
- Human MDP is a purified glycoprotein with a molecular weight of 42 kDa (monomer).
- MDP's substrate specificity suggests a significant role in the metabolism of glutathione and leukotrienes.
- Further research into MDP's function in vivo is warranted.