中文摘要：

在pH=2.9时,细胞色素c保持类天然的结构; 和马来酸-烯烃交替共聚物作用后,细胞色素c的α-螺旋结构基本保持不变,但是三级结构被破坏.另一方面,在pH=2.1时,细胞色素c去折叠形成伸展的无规卷曲构象; 马来酸-烯烃交替共聚物可以诱导酸变性的细胞色素c从无规卷曲构象转变为α-螺旋结构.在酸性溶液中,由于马来酸-异丁烯交替共聚物和细胞色素c之间更强的相互作用,其对蛋白质结构的影响大于马来酸-1-十四烯交替共聚物.相对于小分子,聚合物可以在低浓度条件下提供有利于蛋白质结构转换的微环境.

英文摘要：

The interaction of cytochrome c with two copolymers： poly（isobutylene-alt-maleic acid） （PIMA） and poly（1-tetradecene-alt-maleic acid） （PTMA） was studied in this report to investigate the electrostatic and hydrophobic influence of the copolymers on the structure of cytochrome c at acidic conditions. UV-Vis, circular dichroism and intrinsic tryptophan fluorescence were measured to study the secondary structure, Soret structure and tryptophan environment of cytochrome c. Cytochrome c maintains its native-like structure at pH = 2.9. After interacting with the alternating copolymers of maleic acid and alkene at pH = 2.9, the a-helical structure of cytochrome c is basically unchangeable, whereas its tertiary structure is destroyed. On the other hand, at pH = 2.1, cytochrome c unfolds to random coil, and the alternating copolymers can induce a structural transition to a-helical structure for the acid-denatured cytochrome c but cannot induce the tertiary structure. In acidic solutions with lower copolymer concentration, the influence of PIMA on cytochrome c structure is stronger than that of PTMA, but at higher PTMA concentrations PTMA can reach similar effect as PIMA. The reason may be that at the same copolymer weight concentration, PIMA carries more negative charges therefore has stronger electrostatic interaction with cytochrome c, and that PTMA forms stable particles with hydrophobic cores which may decrease its effective concentration and decrease the interaction with cytochrome c. Compared to small molecules, the polymeric structure provides a favorable microenvironment for the structural transition of protein at very low copolymer concentrations.