Enhanced Peptide Stability Against Protease Digestion
Induced by Intrinsic Factor Binding of a Vitamin B<sub>12</sub> Conjugate
of Exendin‑4
- Publication date
- Publisher
Abstract
Peptide
digestion from proteases is a significant limitation in
peptide therapeutic development. It has been hypothesized that the
dietary pathway of vitamin B<sub>12</sub> (B<sub>12</sub>) may be
exploited in this area, but an open question is whether B<sub>12</sub>-peptide conjugates bound to the B<sub>12</sub> gastric uptake protein
intrinsic factor (IF) can provide any stability against proteases.
Herein, we describe a new conjugate of B<sub>12</sub> with the incretin
peptide exendin 4 that demonstrates picomolar agonism of the glugacon-like
peptide-1 receptor (GLP1-R). Stability studies reveal that Ex-4 is
digested by pancreatic proteases trypsin and chymotrypsin and by the
kidney endopeptidase meprin β. Prebinding the B<sub>12</sub> conjugate to IF, however, resulted in up to a 4-fold greater activity
of the B<sub>12</sub>-Ex-4 conjugate relative to Ex-4, when the IF-B<sub>12</sub>-Ex-4 complex was exposed to 22 μg/mL of trypsin, 2.3-fold
greater activity when exposed to 1.25 μg/mL of chymotrypsin,
and there was no decrease in function at up to 5 μg/mL of meprin
β