Dolla A, Arnoux P, Protasevich I, Lobachov V, Brugna M, Giudici-Orticoni M T, Haser R, Czjzek M, Makarov A, Bruschi M
Laboratoire de Bioénergétique et Ingénierie des protéines, UPR 9036 C.N.R.S., Marseille, France.
Biochemistry. 1999 Jan 5;38(1):33-41. doi: 10.1021/bi981593h.
Aromatic residues in c-type cytochromes might have an important function in the folding and/or electron transferring properties of the molecule. In the tetraheme cytochrome c3 (Mr 13 000) from Desulfovibrio vulgaris Hildenborough, Phe20, is located between heme 1 and heme 3 with its aromatic ring close and almost parallel to the ring plane of heme 1. We replaced this residue by a nonaromatic hydrophobe residue, leucine, and analyzed the effects in terms of functional, structural, and physicochemical properties. While the F20L replacement did not have any strong effects on the heme region stability, a decrease of the thermostability of the whole molecule was observed. In the same way, the four macroscopic redox potentials were affected by the mutation as well as the flexibility of the surface loop around heme 4. The F20L replacement itself and/or this structural modification might be responsible for the loss of the intermolecular cooperativity between F20L cytochrome c3 molecules.
c型细胞色素中的芳香族残基可能在分子的折叠和/或电子传递特性中发挥重要作用。在来自普通脱硫弧菌希登伯勒菌株的四血红素细胞色素c3（分子量13000）中，苯丙氨酸20位于血红素1和血红素3之间，其芳香环靠近血红素1的环平面且几乎与之平行。我们用非芳香族疏水残基亮氨酸取代了该残基，并从功能、结构和物理化学性质方面分析了其影响。虽然F20L取代对血红素区域稳定性没有强烈影响，但观察到整个分子的热稳定性有所下降。同样，四个宏观氧化还原电位受到突变的影响，血红素4周围表面环的灵活性也受到影响。F20L取代本身和/或这种结构修饰可能是F20L细胞色素c3分子间协同性丧失的原因。
