Fujii Sotaro, Masanari Misa, Inoue Hiroki, Yamanaka Masaru, Wakai Satoshi, Nishihara Hirofumi, Sambongi Yoshihiro
Graduate School of Biosphere Science, Hiroshima University.
Biosci Biotechnol Biochem. 2013;77(8):1677-81. doi: 10.1271/bbb.130226. Epub 2013 Aug 7.
Sequence analysis indicated that thermophilic Hydrogenophilus thermoluteolus cytochrome c' (PHCP) and its mesophilic homolog, Allochromatium vinosum cytochrome c' (AVCP), closely resemble each other in a phylogenetic tree of the cytochrome c' family, with 55% sequence identity. The denaturation temperature of PHCP was 87 °C, 35 °C higher than that of AVCP. Furthermore, PHCP exhibited a larger enthalpy change value during its thermal denaturation than AVCP. While AVCP was dimeric, as observed previously, PHCP was trimeric, and this was the first observation as a cytochrome c'. Dissociation of trimeric PHCP and its protein denaturation reversibly occurred at the same time in a two-state transition manner. Therefore, PHCP is enthalpically more stable than AVCP, perhaps due to its unique trimeric form, in addition to the lower number of Gly residues in its putative α-helical regions.
序列分析表明，嗜热栖热嗜氢菌细胞色素c'（PHCP）及其嗜温同源物，嗜硫红假单胞菌细胞色素c'（AVCP），在细胞色素c'家族的系统发育树中彼此非常相似，序列同一性为55%。PHCP的变性温度为87℃，比AVCP高35℃。此外，PHCP在热变性过程中表现出比AVCP更大的焓变值。正如之前观察到的，AVCP是二聚体，而PHCP是三聚体，这是首次作为细胞色素c'被观察到。三聚体PHCP的解离及其蛋白质变性以双态转变的方式同时可逆地发生。因此，PHCP在焓方面比AVCP更稳定，这可能是由于其独特的三聚体形式，以及其假定的α-螺旋区域中较少的甘氨酸残基数量。
