Fluorogenic substrates for the enkephalin-degrading neutral endopeptidase (Enkephalinase)

Area of Science:

• Biochemistry
• Neuroscience
• Enzymology

Background:

• Rat brain neutral endopeptidase, or enkephalinase, plays a role in neuropeptide metabolism.
• Understanding its substrate specificity is crucial for studying its function in the brain.

Purpose of the Study:

• To characterize the substrate specificity of rat brain neutral endopeptidase.
• To develop a sensitive assay for measuring enkephalinase activity.
• To compare the enzyme's properties with related proteases like thermolysin.

Main Methods:

• Synthesis and use of novel fluorogenic substrates with the general structure 2-aminobenzoyl-(amino acid)n-leucylalanylglycine-4-nitrobenzylamide.
• Competitive inhibition assays using Leu5-enkephalin to confirm substrate identity.
• Testing the efficacy of known thermolysin-like enzyme inhibitors.

Main Results:

• Rat brain neutral endopeptidase hydrolyzed the synthetic fluorogenic substrates.
• Hydrolysis was competitively inhibited by Leu5-enkephalin, confirming substrate engagement.
• The enzyme's activity was inhibited by thermolysin inhibitors, indicating shared specificity.

Conclusions:

• Rat brain neutral endopeptidase exhibits substrate specificity similar to thermolysin.
• The developed fluorogenic substrates provide a sensitive and continuous assay for enkephalinase.
• This substrate class can be valuable for further investigations into enkephalinase specificity.