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Chen Y, Xi X, Ma C, Zhou M, Chen X, Ye Z, Ge L, Wu Q, Chen T, Wang L, Kwok HF. Structure-Activity Relationship and Molecular Docking of a Kunitz-Like Trypsin Inhibitor, Kunitzin-AH, from the Skin Secretion of Amolops hainanensis. Pharmaceutics 2021; 13:pharmaceutics13070966. [PMID: 34206897 PMCID: PMC8309051 DOI: 10.3390/pharmaceutics13070966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 01/10/2023] Open
Abstract
Kunitz-like trypsin inhibitors are one of the most noteworthy research objects owing to their significance in pharmacological studies, including anticarcinogenic activity, obesity regulation and anticoagulation. In the current study, a novel Kunitz-like trypsin inhibitor, Kunitzin-AH, was isolated from the skin secretion of Amolops hainanensis. The novel peptide displayed a modest trypsin inhibitory activity with the inhibitor constant (Ki) value of 1.18 ± 0.08 µM without inducing damage to healthy horse erythrocytes. Then, a series of shortened variants of Kunitzin-AH were designed by truncating a peptide loop and site mutation inside the loop to illustrate the structure–activity relationship of the trypsin inhibition function. Among the variants, a significant decrease was observed for the Cys-Cys loop domain, while the extension of an Arg at N-terminus (RCKAAFC) retained the inhibitory activity, indicating that the -RCK-motif is essential in forming the reactive domain for exerting the inhibitory activity. Furthermore, substitutions of Ala by hydrophobic or hydrophilic residues decreased the activity, indicating suitable steric hindrance provides convenience for the combination of trypsin. Additionally, the conformational simulation of the analogues processed with Chimera and Gromacs and further combination simulations between the peptides and trypsin conducted with HDOCK offered a potential opportunity for the natural trypsin inhibitory drug design. The truncated sequence, AH-798, may be a good replacement for the full-length peptide, and can be optimized via cyclization for further study.
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Affiliation(s)
- Yuqing Chen
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Xinping Xi
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
- Correspondence: (X.X.); (H.F.K.)
| | - Chengbang Ma
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Mei Zhou
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Xiaoling Chen
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Zhuming Ye
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Lilin Ge
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (L.G.); (Q.W.)
| | - Qinan Wu
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (L.G.); (Q.W.)
| | - Tianbao Chen
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Lei Wang
- School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; (Y.C.); (C.M.); (M.Z.); (X.C.); (Z.Y.); (T.C.); (L.W.)
| | - Hang Fai Kwok
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
- Correspondence: (X.X.); (H.F.K.)
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