Design, synthesis, and characterization of a photoactivatable flavocytochrome molecular maquette.
Design, synthesis, and characterization of a photoactivatable flavocytochrome molecular maquette.
复制标题
光活化黄细胞色素分子模型的设计、合成和表征。
DOI：
10.1073/pnas.95.18.10465
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发表时间：
1998
影响因子：
11.1
通讯作者：
Dutton,PL
中科院分区：
文献类型：
--
作者：
Sharp,RE;Moser,CC;Rabanal,F;Dutton,PL
我们报道了一种人工合成的黄素-血红素蛋白的构建，它结合了黄素蛋白的两个主要生理活性：类似于DNA光解酶的黄素的光激活以及黄素和血红素辅因子之间的快速分子内电子转移，就像几种氧化还原酶一样。功能性TETRA-α-螺旋蛋白由两个62-AA螺旋-环-螺旋亚基组成。每个亚基都含有一个半胱氨酸，黄素(7-乙酰-10-甲基异氧嘧啶)共价连接到这个半胱氨酸上，而两个组氨酸与血红素辅因子的配位是适当的。黄素和亚铁血红素都位于蛋白质的疏水核心内。研究了原卟啉IX和1-甲基-2-氧杂环己烯XIII在溶液中由牺牲电子供体光还原生成的黄半喹酮的分子内电子转移。激光脉冲激活的电子从黄素到中位血红素的转移发生在100 ns的时间尺度上，其有利的自由能约为−100 meV。在连续光照下，黄素与低电势原卟啉IX之间的电子转移在一段滞后阶段后发生，且具有不利的自由能。因此，支持肽基质为紧密并列的氧化还原基团的定位提供了一个很好的框架，能够促进分子内的电子转移，并开始在一个简化和可延展的系统中阐明黄素蛋白的自然工程。
We report the construction of a synthetic flavo-heme protein that incorporates two major physiological activities of flavoproteins: light activation of flavin analogous to DNA photolyase and rapid intramolecular electron transfer between the flavin and heme cofactors as in several oxidoreductases. The functional tetra-α-helix protein comprises two 62-aa helix-loop-helix subunits. Each subunit contains a single cysteine to which flavin (7-acetyl-10-methylisoalloxazine) is covalently attached and two histidines appropriately positioned forbis-his coordination of heme cofactors. Both flavins and hemes are situated within the hydrophobic core of the protein. Intramolecular electron transfer from flavosemiquinone generated by photoreduction from a sacrificial electron donor in solution was examined between protoporphyrin IX and 1-methyl-2-oxomesoheme XIII. Laser pulse-activated electron transfer from flavin to meso heme occurs on a 100-ns time scale, with a favorable free energy of approximately −100 meV. Electron transfer from flavin to the lower potential protoporphyrin IX, with an unfavorable free energy, can be induced after a lag phase under continuous light illumination. Thus, the supporting peptide matrix provides an excellent framework for the positioning of closely juxtaposed redox groups capable of facilitating intramolecular electron transfer and begins to clarify in a simplified and malleable system the natural engineering of flavoproteins.