Stability of synthetic exendin-4 in human plasma in vitro.

Sites of exendin-4 that that are relatively susceptible to degradation in plasma were identified with the aim of providing information for designing new exendin-4 analogues. The stability of exendin-4 in human plasma was evaluated in vitro. The results showed that the peptide was slowly degraded with a half-life of 9.57 h and the principal cleavage sites are between Thr5 and Phe6, Phe6 and Thr7, and Thr7 and Ser8 of the N-terminus region of exendin-4.