Construction and validation of a method for detecting DPP-IV activity and tissue distribution in C57 mice based on fluorescent probe

Abstract

Dipeptidyl peptidase-IV (DPP-IV) is critical for drug metabolism and physiological regulation. In terms of species differences of DPP-IV, mouse an d human share a high degree of similarity，it is usually used as the optimal animal model for conducting relevant pharmacological evaluations and biological funct ion studies. Herein, this study developed a detection method using fluorescent probe GP-BAN and mouse tissue S9 fraction (enzyme source) to rapidly quanti fy DPP-IV activity in mouse tissues. Validated for specificity, linearity and pre cision, metabolite BAN showed good linearity in 0-20 μM (r² = 0.9996), with LOD of 5.5 nM and LOQ of 16.7 nM. In C57 mice, DPP-IV activity in 14 ti ssues/organs (liver, kidney, thymus, small intestine included) differed significant ly: thymus had the highest activity (2.64 nM/μg protein/min), followed by liver, kidneyand small intestine. Enzyme kinetics showed GP-BAN's K m for mouse DPP-IV was 34.05 μM, close to human liver microsomes (HLM, 41.46 μM), i ndicating cross-species substrate binding consistency. ELISA confirmed DPP-IV protein expression correlated positively with activity in liver, kidney and thym us (r > 0.92, p < 0.001). This sensitive, species-translatable assay and its orga n-specific activity/kinetic data support mouse models in preclinical DPP-IV stud ies, improving cross-species extrapolation predictability in physiological research.