Synthetic exendin-4 exhibits dose-dependent glucose-regulatory activity similar to that of native glucagon-like peptide-1(GLP-1). Moreover, exendin-4 is resistant to degradation by dipeptidyl peptidase-Ⅳ(DPP-Ⅳ) whil...Synthetic exendin-4 exhibits dose-dependent glucose-regulatory activity similar to that of native glucagon-like peptide-1(GLP-1). Moreover, exendin-4 is resistant to degradation by dipeptidyl peptidase-Ⅳ(DPP-Ⅳ) while GLP-1 is degraded by DPP-Ⅳ with a half-life of less than 2 min in mammals. In this study the stability of exendin-4 in human plasma was evaluated in vitro. Exendin-4 was incubated in plasma at 37 ℃, extracted and subsequently analyzed by using high performance liquid chromatography(HPLC). Exendin-4 was slowly broken down in plasma. Its half-life time is 9.57 h. The degradation products were identified by mass-spectrum(MS). According to natural sequence of exendin-4, we deduced that the cleavage were between the Thr5 and Phe6 bond, Phe6 and Thr7 bond, and Thr7 and Ser8 bond of the N-terminus region of the peptide, and the results of ESI-TOF-MS prove that our primary conclusion was correct.展开更多
Exendin-4 is an incretin mimetic that has been studied as a potent drug for the treatment of the type 2 diabetes. To screen the shorter analogues of Exendin-4 that have the same bioactivity,we designed two analogues o...Exendin-4 is an incretin mimetic that has been studied as a potent drug for the treatment of the type 2 diabetes. To screen the shorter analogues of Exendin-4 that have the same bioactivity,we designed two analogues of Exendin-4: Ex1,deleting this sequence and Ex2,replacing this sequence with three Alas. The proliferation assay of RINm-5F cell using MTT suggested the bioactivity of Ex1 and Ex2 was lower compared to that of Exendin-4 caused by the deletion of LSKQMEEEA. Ex1 and Ex2 had the same strong stability against DPPⅣ with Exendin-4. CD data suggested the helix content of Ex1 had a significant lost,but the helix content of Ex2 was the same as that of Exendin-4. The emission maximum of Ex1 was red-shifted of 3 nm relative to Exendin-4,the absence of this sequence made Trp25 more apt to hydrophilic and the Trp-cage became looser. So we have designed Ex2,the mimetic of Exendin-4 that had the same bioactivity and strong stability against DPPⅣ with Exendin-4 successfully. It became a solid foundation for designing shorter analogues of Exendin-4 for oral drug of diabetes.展开更多
文摘Synthetic exendin-4 exhibits dose-dependent glucose-regulatory activity similar to that of native glucagon-like peptide-1(GLP-1). Moreover, exendin-4 is resistant to degradation by dipeptidyl peptidase-Ⅳ(DPP-Ⅳ) while GLP-1 is degraded by DPP-Ⅳ with a half-life of less than 2 min in mammals. In this study the stability of exendin-4 in human plasma was evaluated in vitro. Exendin-4 was incubated in plasma at 37 ℃, extracted and subsequently analyzed by using high performance liquid chromatography(HPLC). Exendin-4 was slowly broken down in plasma. Its half-life time is 9.57 h. The degradation products were identified by mass-spectrum(MS). According to natural sequence of exendin-4, we deduced that the cleavage were between the Thr5 and Phe6 bond, Phe6 and Thr7 bond, and Thr7 and Ser8 bond of the N-terminus region of the peptide, and the results of ESI-TOF-MS prove that our primary conclusion was correct.
文摘Exendin-4 is an incretin mimetic that has been studied as a potent drug for the treatment of the type 2 diabetes. To screen the shorter analogues of Exendin-4 that have the same bioactivity,we designed two analogues of Exendin-4: Ex1,deleting this sequence and Ex2,replacing this sequence with three Alas. The proliferation assay of RINm-5F cell using MTT suggested the bioactivity of Ex1 and Ex2 was lower compared to that of Exendin-4 caused by the deletion of LSKQMEEEA. Ex1 and Ex2 had the same strong stability against DPPⅣ with Exendin-4. CD data suggested the helix content of Ex1 had a significant lost,but the helix content of Ex2 was the same as that of Exendin-4. The emission maximum of Ex1 was red-shifted of 3 nm relative to Exendin-4,the absence of this sequence made Trp25 more apt to hydrophilic and the Trp-cage became looser. So we have designed Ex2,the mimetic of Exendin-4 that had the same bioactivity and strong stability against DPPⅣ with Exendin-4 successfully. It became a solid foundation for designing shorter analogues of Exendin-4 for oral drug of diabetes.
