Live Fluorescence Imaging of Exogenous Enzyme Action in the Gastrointestinal Tract
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Because these enzymes are protein-based, they can be inactivated and/or digested in the gastrointestinal (GI) tract.
A research team recently established a convenient fluorescence-based test to measure the activity of therapeutic enzymes live and in real time in the GI tract.
The research team included Gregor Fuhrmann and Jean-Christophe Leroux. They are affiliated with the Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences in Zurich, Switzerland.
To establish proof of their principle, the team applied their assay to proline-specific endopeptidases (PEPs), a group of enzymes recently proposed as adjuvant therapy for celiac disease, which is a very common immunogenetic enteropathy.
To do so, they took a short PEP-specific peptide sequence from larger immunotoxic sequences of gluten. They then labeled each sequence with a fluorescent dye and a corresponding quencher.
Once the enzyme sequence split, they dequenched the fluorescence emission and then used an live imaging system to detect the result.
The team then evaluated PEPs originating from Flavobacterium meningosepticum (FM) and Myxococcus xanthus (MX) after oral administration in rats.
While MX PEP could not split the peptide in the stomach, FM PEP showed significant gastric activity reaching 40–60% of the maximal live signal intensity. However, both enzymes produced similar fluorescence signals in the small intestine.
Using an antacid significantly enhanced MX PEP’s gastric activity due to increased pH and/or inhibition of stomach proteases. By using this simple method, the team was able to observe differences in the live performance of PEPs, which could not be identified under laboratory conditions.
This imaging method could be used for live study other oral enzymes and may prove useful in improving current treatments.
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