RESUMEN
Objective: To design and synthesize APC/Asef peptide inhibitors and investigate the structure-activity relationship between peptides inhibitors and APC protein for exploring better inhibitors. Methods: Based on the best-class inhibitor we had found before-MAI-400, eleven peptide inhibitors were designed, which included the changes of N-terminal capping group, the first amino acid Ala, the fifth amino acid Leu and the last amino acid Glu. According to the results of fluorescence polarization activity detection system and molecular docking, the structure-activity relationship of peptide inhibitors was investigated. Results: Among the eleven peptides, MPI-11 had the highest affinity, whose half maximal inhibitory concentration (IC50) was 0.973 1 mmol/L. The capping group of peptide N-terminal with tert-butoxycarbonyl group reduced the activity slightly. The substitution of the Ala caused different results, changing into Trp, His and Thr definitely reduced the activity but the substitution by Tyr or Phe did not influence the activity too much. And introducing benzene ring into the side chain of Leu had few effects on activity improving. The substitution of side chain carboxyl for amide at the C-terminal glutamate had little effect on the activity. Conclusion: Among the eleven peptides, the capping group of peptide N-terminal cannot be substituted into small groups and Ala cannot be substituted into other amino acids.
RESUMEN
Objective: To design and synthesize APC/Asef peptide inhibitors, and investigate the relationship between the structures and affinity of peptides. Methods: Based on crystal structure of the APC-MAI-150 complex, on the one hand, 3-phenylpropane, Glu-Glu (GG) and β-Ala-Ala (β-AA) were used to replace carbobenzoxy (CBZ) at the N terminal of MAI-150 to bind -NH2; on the other hand, -CN, -NO2, -NH2, and -F were replaced the parahydroxyl on the sixth tyrosine (Tyr) side chain benzene at the N terminal of MAI-150. And seven peptides were synthesized. Fluorescence polarization was applied to test peptide affinity, and molecular design laboratory-3 (MDL-3), MDL-4 and MDL-5 were docked into APC protein based on the results of activity. The structure-activity relationship of the three peptides was studied by combining the binding patterns of computer docked peptide and APC protein. Results: Among the seven peptides, the N terminal 3-phenylpropane linked -NH2 of peptide MDL-5 had the highest affinity, which IC50 was 2.35 μmol/L. Compared with MDL-5, the affinity of MDL-6 and MDL-7 were significantly reduced. The para-hydroxyl on the sixth Tyr side chain benzene at the N terminal replaced with -NH2 (MDL-3) and -F (MDL-4), which the affinity were higher than -CN (MDL-1) and -NO2 (MDL-2). However, the affinity of newly synthesized peptides was lower than MAI-150. Conclusion: Transforming peptide N terminal linked -NH2 and the para-hydroxyl group on the sixth Tyr side chain benzene doesn't help to improve the affinity of peptides.