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Purification of membrane-bound aminopeptidase from rat brain: identification of aminopeptidase M
Abstract:
Two different membrane-bound aminopeptidases were isolated from rat brain membranes, one with a puromycin sensitive activity and the other, not affected by 10 microM puromycin. The physicochemical, catalytic and immunological properties of the latter were compared to those of aminopeptidase M purified from rat kidney membranes and allowed us to conclude to large similarities between these two enzymes. Because the two brain aminopeptidases were both sensitive to bestatin, it remains to be established whether both or only aminopeptidase M is involved in endogenous enkephalin inactivation.
Insights
Researchers identified two membrane-bound aminopeptidases in rat brains. One enzyme, similar to kidney aminopeptidase M, showed significant similarities, suggesting its role in enkephalin inactivation.
Area of Science:
- Neuroscience
- Biochemistry
- Enzymology
Background:
- Membrane-bound aminopeptidases play crucial roles in cellular processes.
- Rat brain membranes contain enzymes involved in peptide metabolism.
- Endogenous opioid peptides like enkephalins are regulated by peptidases.
Purpose of the Study:
- To isolate and characterize membrane-bound aminopeptidases from rat brain.
- To compare the properties of brain aminopeptidases with known enzymes like rat kidney aminopeptidase M.
- To investigate the potential involvement of these enzymes in endogenous enkephalin inactivation.
Main Methods:
- Isolation and purification of two distinct membrane-bound aminopeptidases from rat brain.
- Biochemical characterization including sensitivity to inhibitors like puromycin and bestatin.
- Comparative analysis of physicochemical, catalytic, and immunological properties.
Main Results:
- Two puromycin-sensitive and puromycin-insensitive aminopeptidases were isolated from rat brain membranes.
- The puromycin-insensitive brain aminopeptidase exhibited significant similarities to purified rat kidney aminopeptidase M.
- Both isolated brain aminopeptidases demonstrated sensitivity to the inhibitor bestatin.
Conclusions:
- Rat brain contains an aminopeptidase M-like enzyme with properties similar to the kidney form.
- Further investigation is required to determine if both or only aminopeptidase M is responsible for inactivating enkephalins in the brain.
- The findings contribute to understanding neuropeptide metabolism and the roles of specific peptidases in the central nervous system.