Dolla A, Guerlesquin F, Bruschi M, Haser R
Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique, Marseille, France.
J Mol Recognit. 1991 Feb;4(1):27-33. doi: 10.1002/jmr.300040105.
To specify electron exchanges involving Desulfovibrio desulfuricans Norway tetra-heme cytochrome c3, the chemical modification of arginine 73 residue, was performed. Biochemical and biophysical studies have shown that the modified cytochrome retains its ability to both interact and act as an electron carrier with its redox partners, ferredoxin and hydrogenase. Moreover, the chemical modification effects on the cytochrome c3 1H NMR spectrum were similar to that induced by the presence of ferredoxin. This suggests that arginine 73 is localized on the cytochrome c3 ferredoxin interacting site. The identification of heme 4, the closest heme to arginine 73, as the ferredoxin interacting heme helps us to hypothesize about the role of the three other hemes in the molecule. A structural hypothesis for an intramolecular electron transfer pathway, involving hemes 4, 3 and 1, is proposed on the basis of the crystal structures of D. vulgaris Miyazaki and D. desulfuricans Norway cytochromes c3. The unique role of some structural features (alpha helix, aromatic residues) intervening between the heme groups, is proposed.
为了明确涉及脱硫脱硫弧菌挪威四血红素细胞色素c3的电子交换，对精氨酸73残基进行了化学修饰。生物化学和生物物理学研究表明，修饰后的细胞色素保留了与氧化还原伙伴铁氧化还原蛋白和氢化酶相互作用并作为电子载体发挥作用的能力。此外，化学修饰对细胞色素c3的1H NMR谱的影响与铁氧化还原蛋白存在时诱导的影响相似。这表明精氨酸73位于细胞色素c3铁氧化还原蛋白相互作用位点上。确定与精氨酸73最接近的血红素4为与铁氧化还原蛋白相互作用的血红素，有助于我们推测分子中其他三个血红素的作用。基于普通脱硫弧菌宫崎株和脱硫脱硫弧菌挪威细胞色素c3的晶体结构，提出了一个涉及血红素4、3和1的分子内电子转移途径的结构假说。还提出了位于血红素基团之间的一些结构特征（α螺旋、芳香族残基）的独特作用。
