The pigment binding behaviour of water-soluble chlorophyll protein (WSCP)
The pigment binding behaviour of water-soluble chlorophyll protein (WSCP)
复制标题
水溶性叶绿素蛋白（WSCP）的色素结合行为
DOI：
10.1039/d0pp00043d
复制
发表时间：
2020
影响因子：
3.1
通讯作者：
H. Paulsen
中科院分区：
文献类型：
--
作者：
P. Girr;Jessica Kilper;Anne;H. Paulsen
水溶性叶绿素蛋白（WSCPs）是一种同四聚体蛋白，可以在相同的结合位点结合4个叶绿素分子，这使得WSCPs成为研究蛋白质-色素相互作用的良好模型。在之前的研究中，我们描述了Chl a或Chl b在各种WSCP版本中的优先结合。当氯大环的C_7甲酰基与蛋白质之间能形成氢键时，首选Chl b结合，而当Chl b结合在空间上不利时，首选Chl a结合。在这里，我们测定了不同WSCP版本不仅对Chl a/b，而且对叶绿素（Chlide） a/b和叶绿素（Pheo） a/b的结合亲和力和动力学。k_d值的改变是WSCP中Chl a/b选择性的原因，而反应动力学的差异在解释不同的Chl a/b偏好时可以忽略不计。与Chl相比，WSCP对Chlide和Pheo的亲和力较低，这表明叶绿醇链和中心的Mg^2+离子是WSCP与色素相互作用的重要位点。由于既缺乏叶绿醇链，又缺乏中心的Mg^2+离子，因此只能以Pheoide b的形式结合到对Chl b的亲和力高于Chl a的WSCP上，这强调了c_7甲酰基-蛋白质相互作用的影响。此外，WSCP能够与原叶绿内酯和mg -原卟啉IX结合，这表明大环π电子系统的大小和大环上是否存在第五环对WSCP的结合没有显著影响。WSCP还与血红素结合形成四聚体复合物，表明血红素在chl结合位点结合。
Water-soluble chlorophyll proteins (WSCPs) are homotetrameric proteins that bind four chlorophyll (Chl) molecules in identical binding sites, which makes WSCPs a good model to study protein–pigment interactions. In a previous study, we described preferential binding of Chl a or Chl b in various WSCP versions. Chl b binding is preferred when a hydrogen bond can be formed between the C_7 formyl of the chlorin macrocycle and the protein, whereas Chl a is preferred when Chl b binding is sterically unfavorable. Here, we determined the binding affinities and kinetics of various WSCP versions not only for Chl a/b , but also for chlorophyllide (Chlide) a/b and pheophytin (Pheo) a/b . Altered K _D values are responsible for the Chl a/b selectivity in WSCP whereas differences in the reaction kinetics are neglectable in explaining different Chl a/b preferences. WSCP binds both Chlide and Pheo with a lower affinity than Chl, which indicates the importance of the phytol chain and the central Mg^2+ ion as interaction sites between WSCP and pigment. Pheophorbide (Pheoide), lacking both the phytol chain and the central Mg^2+ ion, can only be bound as Pheoide b to a WSCP that has a higher affinity for Chl b than Chl a, which underlines the impact of the C_7formyl-protein interaction. Moreover, WSCP was able to bind protochlorophyllide and Mg-protoporphyrin IX, which suggests that neither the size of the π electron system of the macrocycle nor the presence of a fifth ring at the macrocycle notably affect the binding to WSCP. WSCP also binds heme to form a tetrameric complex, suggesting that heme is bound in the Chl-binding site.
登录
查看更多内容
影响因子：
4.6
作者：
Agostini A;Palm DM;Schmitt FJ;Albertini M;Valentin MD;Paulsen H;Carbonera D
通讯作者：
Carbonera D
影响因子：
2.9
作者：
Brigé, A;Leys, D;Van Beeumen, JJ
通讯作者：
Van Beeumen, JJ
影响因子：
18
作者：
Palm, Daniel M.;Agostini, Alessandro;Paulsen, Harald
通讯作者：
Paulsen, Harald
影响因子：
2.9
作者：
Palm, Daniel M.;Agostini, Alessandro;Paulsen, Harald
通讯作者：
Paulsen, Harald