Structural transformation of cytochrome c and apo cytochrome c induced by sulfonated polystyrene
Structural transformation of cytochrome c and apo cytochrome c induced by sulfonated polystyrene
复制标题
磺化聚苯乙烯诱导细胞色素c和脱辅基细胞色素c的结构转变
DOI：
10.1021/bm034090m
复制
发表时间：
2003-09-01
影响因子：
6.2
通讯作者：
Chunyu, L
中科院分区：
文献类型：
--
作者：
Gong, J;Yao, P;Chunyu, L
研究了不同电荷密度（磺化度）和链长的磺化聚苯乙烯（SPS）对细胞色素c（cyt c）及其脱血红素前体apo cyt c结构的影响. SPS在水溶液中形成稳定的透明纳米颗粒。主链和苯基基团的疏水缔合通过颗粒表面上的磺酸盐基团的静电排斥来平衡。细胞色素c与带负电荷的SPS颗粒的结合导致细胞色素c的天然致密结构的广泛破坏：Fe-Met 80配体的裂解，约40%的螺旋结构损失，以及Trp 59的不对称环境的破坏。另一方面，SPS颗粒结合的apo cyt c经历了从无规卷曲到α-螺旋结构的构象变化。载脂细胞色素c在SPS颗粒中的折叠受溶液的pH和离子强度、SPS浓度、SPS的磺化度和链长的影响。在溶液中，折叠可以达到天然cyt c α-螺旋含量的90%以上。聚（4-苯乙烯磺酸钠）（PSS），这是100%磺化聚苯乙烯，不能在溶液中形成疏水核，诱导只有三分之二的α-螺旋含量相比，SPS。PSS/SPS与apo cyt c的静电相互作用诱导apo cyt c早期部分折叠。apo cyt c的非极性残基与SPS颗粒的疏水核心之间的疏水相互作用延伸了apo cyt c的α-螺旋结构。
The structural transformation of cytochrome c (cyt c) and its heme-free precursor, apo cyt c, induced by negatively charged sulfonated polystyrene (SPS) with different charge density (degree of sulfonation) and chain length was studied to understand the factors that influence the folding and unfolding of the protein. SPS forms stable transparent nanoparticles in aqueous solution. The hydrophobic association of the backbone chain and phenyl groups is balanced by the electrostatic repulsion of the sulfonate groups on the particle surface. The binding of cyt c to negatively charged SPS particles causes an extensive disruption of the native compact structure of cyt c: the cleavage of Fe-Met80 ligand, about 40% loss of the helical structure, and the disruption of the asymmetry environment of Trp59. On the other hand, SPS particle-bound apo cyt c undergoes a conformational change from the random coil to alpha-helical structure. The folding of apo cyt c in SPS particles was influenced by pH and ionic strength of the solution, SPS concentration, and the degree of sulfonation and chain length of SPS. The folding can reach more than 90% of the alpha-helix content of native cyt c in solution. Poly(sodium 4-styrenesulfonate) (PSS), which is 100% sulfonated polystyrene and cannot form hydrophobic cores in the solution, induces only two-thirds of the alpha-helix content compared with SPS. It appears that the electrostatic interaction between PSS/SPS and apo cyt c induces an early partially folded state of apo cyt c. The hydrophobic interaction between nonpolar residues in apo cyt c and the hydrophobic cores in SPS particles extends the alpha-helical structure of apo cyt c.