Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen ca...Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen calmodulin(pCaM). Fluorescence titration experiments demonstrated that BPP 1 had no affinity for pCaM while its C terminal amide, BPP 2, had fair affinity for pCaM(dissociation constant of pCaM peptide complex, K d=2.9× 10 -1 μmol/L) due to the decrease in \{C terminal polarity.\} But compared with BPP 3( K d=8.1× 10 -2 μmol/L), which was also a peptide amide, BPP 2 had a much lower binding ability. In order to investigate other factors influencing peptide affinity for pCaM besides polarity(or hydrophobicity), CD and 2D NMR spectroscopes were used to study the conformations of BPP 1 and BPP 3. It revealed that molecular flexibility could affect peptides ability to bind pCaM. BPP 1 displayed rigid extended peptide bonds in the middle region where the basic amino acid pair Lys 7 Lys 8 is located, flanked by flexible peptide segments on both terminals; while the middle five residue region of BPP 3 exhibited as very flexible segment. Such a structural character might facilitate BPP 3 to adopt a conformation contributive to the interaction of two Lys residues with the acidic residues of pCaM in its peptide binding site and resulted in higher affinity. As this study revealed, both of the two peptides showed the lack of ordered structure in the aqueous solution. It seemed that there was no relationship between peptide affinity for CaM and the propensity of peptide chain to form α helix. This contradicted what most previous researches approved that α helix was an important character of peptide with high affinity for CaM.展开更多
目的探究β2整合素/FLNa相互作用的力学调控机制、磷酸化效应与分子结构基础。方法β2整合素/FLNa-WT和T758P晶体结构取自蛋白质数据库(protein data bank,PDB),进行分子动力学(molecular dynamics,MD)模拟,采用MM/PBSA方法计算复合物...目的探究β2整合素/FLNa相互作用的力学调控机制、磷酸化效应与分子结构基础。方法β2整合素/FLNa-WT和T758P晶体结构取自蛋白质数据库(protein data bank,PDB),进行分子动力学(molecular dynamics,MD)模拟,采用MM/PBSA方法计算复合物结合自由能变化,并分析构象演化与残基相互作用等数据。结果β2整合素THR758磷酸化修饰后,复合物的结合自由能下降,拉力累积降低。单纯的力学信号刺激下,β2整合素/FLNa复合物的解离呈现出双相力依赖特性,而磷酸化后复合物的结合解离过程存在单纯的滑移键机制。结论磷酸化将通过减弱M762-G2269残基相互作用,下调β2整合素/FLNa复合物的结合亲和力,张力将双相调节复合物的解离。研究结果有助于加深对炎症反应过程的认识,并为相关药物靶点的发现和抗体设计提供有益参考。展开更多
文摘Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen calmodulin(pCaM). Fluorescence titration experiments demonstrated that BPP 1 had no affinity for pCaM while its C terminal amide, BPP 2, had fair affinity for pCaM(dissociation constant of pCaM peptide complex, K d=2.9× 10 -1 μmol/L) due to the decrease in \{C terminal polarity.\} But compared with BPP 3( K d=8.1× 10 -2 μmol/L), which was also a peptide amide, BPP 2 had a much lower binding ability. In order to investigate other factors influencing peptide affinity for pCaM besides polarity(or hydrophobicity), CD and 2D NMR spectroscopes were used to study the conformations of BPP 1 and BPP 3. It revealed that molecular flexibility could affect peptides ability to bind pCaM. BPP 1 displayed rigid extended peptide bonds in the middle region where the basic amino acid pair Lys 7 Lys 8 is located, flanked by flexible peptide segments on both terminals; while the middle five residue region of BPP 3 exhibited as very flexible segment. Such a structural character might facilitate BPP 3 to adopt a conformation contributive to the interaction of two Lys residues with the acidic residues of pCaM in its peptide binding site and resulted in higher affinity. As this study revealed, both of the two peptides showed the lack of ordered structure in the aqueous solution. It seemed that there was no relationship between peptide affinity for CaM and the propensity of peptide chain to form α helix. This contradicted what most previous researches approved that α helix was an important character of peptide with high affinity for CaM.
文摘目的探究β2整合素/FLNa相互作用的力学调控机制、磷酸化效应与分子结构基础。方法β2整合素/FLNa-WT和T758P晶体结构取自蛋白质数据库(protein data bank,PDB),进行分子动力学(molecular dynamics,MD)模拟,采用MM/PBSA方法计算复合物结合自由能变化,并分析构象演化与残基相互作用等数据。结果β2整合素THR758磷酸化修饰后,复合物的结合自由能下降,拉力累积降低。单纯的力学信号刺激下,β2整合素/FLNa复合物的解离呈现出双相力依赖特性,而磷酸化后复合物的结合解离过程存在单纯的滑移键机制。结论磷酸化将通过减弱M762-G2269残基相互作用,下调β2整合素/FLNa复合物的结合亲和力,张力将双相调节复合物的解离。研究结果有助于加深对炎症反应过程的认识,并为相关药物靶点的发现和抗体设计提供有益参考。
