scholarly journals Structure–Activity Relationship and Molecular Docking of a Kunitz-Like Trypsin Inhibitor, Kunitzin-AH, from the Skin Secretion of Amolops hainanensis

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 966
Author(s):  
Yuqing Chen ◽  
Xinping Xi ◽  
Chengbang Ma ◽  
Mei Zhou ◽  
Xiaoling Chen ◽  
...  

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.

2020 ◽  
Vol 12 (9) ◽  
pp. 795-811 ◽  
Author(s):  
Yong-Xuan Liu ◽  
Shuang Gao ◽  
Tong Ye ◽  
Jia-Zhong Li ◽  
Fei Ye ◽  
...  

Aim: 4-Hydroxyphenylpyruvate dioxygenase (HPPD) has attracted increasing attention as an important target against tyrosinemia type I. This paper aimed to explore the structure–activity relationship of HPPD inhibitors with pyrazole scaffolds and to design novel HPPD inhibitors. Methodology & results: The best 3D-quantitative structure–activity relationships model was established by two different strategies based on 40 pyrazole scaffold-based analogs. Screening of molecular fragments by topomer technology, combined with molecular docking, 14 structures were identified for potential human HPPD inhibitory activity. Molecular dynamics results demonstrated that all the compounds obtained bound to the enzyme and possessed a satisfactory binding free energy. Conclusion: The quantitative structure–activity relationship of HPPD inhibitors of pyrazole scaffolds was clarified and 14 original structures with potential human HPPD inhibitory activity were obtained.


1978 ◽  
Vol 33 (9-10) ◽  
pp. 695-703 ◽  
Author(s):  
Walter Oettmeier ◽  
Susanne Reimer ◽  
Klaus Link

Abstract 1.4-benzoquinones have been tested for their inhibitory activity on photosynthetic NADP+ reduction by chloroplasts. Benzoquinones with one or two branched alkyl side chains are inhibitors of electron flow. Inhibitory activity can be highly increased if one - and even more if two - halogen substitutents are introduced into the quinone moiety. Iodine substitution yields a better inhibitor than bromine than chlorine. A quantitative structure activity relationship according to a bilinear model, as developed by Kubinyi, with the lipophilicity as the only parameter could be established.


2010 ◽  
Vol 16 (5) ◽  
pp. 242-248 ◽  
Author(s):  
Masakatsu Kamiya ◽  
Keisuke Oyauchi ◽  
Yoshinori Sato ◽  
Takuya Yokoyama ◽  
Mofei Wang ◽  
...  

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 895
Author(s):  
Yaxian Lin ◽  
Siyan Liu ◽  
Xinping Xi ◽  
Chengbang Ma ◽  
Lei Wang ◽  
...  

Antimicrobial peptides (AMPs) are considered potential alternatives to antibiotics due to their advantages in solving antibiotic resistance. Brevinin-2GUb, which was extracted from the skin secretion of Hylarana guentheri, is a peptide with modest antimicrobial activity. Several analogues were designed to explore the structure–activity relationship and enhance its activity. In general, the Rana box is not an indispensable motif for the bioactivity of Brevinin-2GUb, and the first to the 19th amino acids at the N-terminal end are active fragments, such that shortening the peptide while maintaining its bioactivity is a promising strategy for the optimisation of peptides. Keeping a complete hydrophobic face and increasing the net charges are key factors for antimicrobial activity. With the increase of cationic charges, α-helical proportion, and amphipathicity, the activity of t-Brevinin-2GUb-6K (tB2U-6K), in combatting bacteria, drastically improved, especially against Gram-negative bacteria, and the peptide attained the capacity to kill clinical isolates and fungi as well, which made it possible to address some aspects of antibiotic resistance. Thus, peptide tB2U-6K, with potent antimicrobial activity against antibiotic-resistant bacteria, the capacity to inhibit the growth of biofilm, and low toxicity against normal cells, is of value to be further developed into an antimicrobial agent.


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