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. 2021 Feb 15;7(3):454–466. doi: 10.1021/acscentsci.0c01237

Figure 3.

Figure 3

(a) LC-MS/MS total ion chromatogram depicting the stability of GLP1 (maroon) and 2-GLP1 (pink) with (shaded) and without (nonshaded) DPP4. GLP1 incubated with DPP4 shows the same retention time as control GLP1(9–36) (gray) indicating excision of dipeptide His7Ala8 to give cleaved, c, peptide. 2-GLP1 incubated with DPP4 exhibits no change in retention time or mass. (b) LC-MS/MS total ion chromatogram depicting the stability of exenatide (purple) and 2-exenatide (light purple) with (shaded) and without DPP4 (nonshaded). Exenatide incubated with DPP4 results in a mixture of cleaved, c, and native (unreacted), n, exenatide. The retention time of cleaved exenatide, c, is the same as control exenatide(3–39) (gray). 2-Exenatide incubated with DPP4 is unreactive with no change in retention time or mass. (c) LC-MS/MS total ion chromatogram depicting the stability of liraglutide (navy) and 2-liraglutide (light blue) with (shaded) and without DPP4 (nonshaded). Liraglutide incubated with DPP4 results in a mixture of cleaved, c, and native (unreacted), n, liraglutide. 2-Liraglutide incubated with DPP4 does not undergo reaction with unchanged retention time and mass.