Characterization of Novel Dipeptidyl Peptidase-IV Inhibitory Peptides from Soft-Shelled Turtle Yolk Hydrolysate Using Orthogonal Bioassay-Guided Fractionations Coupled with In Vitro and In Silico Study

Nhung Thi Phuong Nong; Yu-Kuo Chen; Wen-Ling Shih; Jue-Liang Hsu

doi:10.3390/ph13100308

Characterization of Novel Dipeptidyl Peptidase-IV Inhibitory Peptides from Soft-Shelled Turtle Yolk Hydrolysate Using Orthogonal Bioassay-Guided Fractionations Coupled with In Vitro and In Silico Study

Pharmaceuticals (Basel). 2020 Oct 14;13(10):308. doi: 10.3390/ph13100308.

Authors

Nhung Thi Phuong Nong^{1

2}, Yu-Kuo Chen³, Wen-Ling Shih⁴, Jue-Liang Hsu^{4

5

6}

Affiliations

¹ Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
² Department of Basic Science, Thainguyen University of Agriculture and Forestry, Quyetthang Ward, Thai Nguyen 250000, Vietnam.
³ Department of Food Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
⁴ Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
⁵ International Master's Degree Program in Food Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
⁶ Research Center for Animal Biologics, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.

Abstract

Five novel peptides (LPLF, WLQL, LPSW, VPGLAL, and LVGLPL) bearing dipeptidyl peptidase IV (DPP-IV) inhibitory activities were identified from the gastrointestinal enzymatic hydrolysate of soft-shelled turtle yolk (SSTY) proteins. Peptides were isolated separately using reversed-phase (RP) chromatography in parallel with off-line strong cation exchange (SCX) chromatography followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to determine sequences. Among these peptides, LPSW showed the highest DPP-IV inhibitory activity with an IC₅₀ value of 269.7 ± 15.91 µM. The results of the pre-incubation experiment and the kinetic study of these peptides indicated that WLQL is a true inhibitor and its inhibition toward DPP-IV is of an uncompetitive model, while LPLF, LPSW, and VPGLAL are real-substrates and competitive inhibitors against DPP-IV. The DPP-IV inhibitory peptides derived from SSTY hydrolysate in study are promising in the management of hyperglycemia in Type 2 diabetes.

Keywords: DPP-IV inhibitory peptides; LC-MS/MS; bioassay-guided fractionation; in silico analysis; soft-shelled turtle yolk protein.

Abstract

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