On the optimal relative orientation of radicals in the cryptochrome magnetic compass
On the optimal relative orientation of radicals in the cryptochrome magnetic compass
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DOI：
10.1063/1.5115445
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发表时间：
2019-08-14
影响因子：
4.4
通讯作者：
Kattnig, Daniel R.
中科院分区：
文献类型：
--
作者：
Atkins, Chadsley;Bajpai, Kieran;Kattnig, Daniel R.
鸟类似乎天生就有磁性指南针。这种意义上的一个生物物理模型依赖于蛋白质隐花色素中光生自由基对的自旋动力学。本研究采用了一种系统的方法来预测的依赖罗盘的灵敏度上的相对取向的组成自由基的自旋系统，包括多达21个超精细相互作用。指南针的灵敏度（各向异性）和精度（最优性）来自单重产量的评估措施，我们发现理想的相对取向的自由基对组成的黄素阴离子（F中心点-）加上色氨酸阳离子（W中心点+）或酪氨酸自由基（Y-中心点）。对于地磁场，这两个度量在[F中心点- W中心点+]中是相关的。径向基芳香平面的法线所跨越的角度是决定罗盘灵敏度的决定性参数。色氨酸三联体/四联体的第三个色氨酸与磁敏反应有关，表现出极大的各向异性，但不具有最优性。通过优化自由基的相对取向，其各向异性可提高约50%。对于1 μ s的相干寿命，[F中心点- W中心点+]的最大相对各向异性为0.27%。对于大多数相对方向，[F中心点-Y中心点]根对优于[F中心点- W中心点+]。此外，各向异性和最优性可以同时最大化。纠缠迅速衰减，暗示它是一种情境副产品，而不是鸟类罗盘内的基本驱动力。在更高强度的磁场中，[F中心点- W中心点+]中游离基的相对取向不如地磁场重要。由AIP Publishing授权出版。
Birds appear to be equipped with an innate magnetic compass. One biophysical model of this sense relies on spin dynamics in photogenerated radical pairs in the protein cryptochrome. This study employs a systematic approach to predict the dependence of the compass sensitivity on the relative orientation of the constituent radicals for spin systems comprising up to 21 hyperfine interactions. Evaluating measures of compass sensitivity (anisotropy) and precision (optimality) derived from the singlet yield, we find the ideal relative orientations for the radical pairs consisting of the flavin anion (F center dot-) coupled with a tryptophan cation (W center dot+) or tyrosine radical (Y-center dot). For the geomagnetic field, the two measures are found to be anticorrelated in [F center dot- W center dot+]. The angle spanned by the normals to the aromatic planes of the radicals is the decisive parameter determining the compass sensitivity. The third tryptophan of the tryptophan triad/tetrad, which has been implicated with magnetosensitive responses, exhibits a comparably large anisotropy, but unfavorable optimality. Its anisotropy could be boosted by an additional similar to 50% by optimizing the relative orientation of the radicals. For a coherent lifetime of 1 mu s, the maximal relative anisotropy of [F center dot- W center dot+] is 0.27%. [F center dot- Y-center dot] radical pairs outperform [F center dot- W center dot+] for most relative orientations. Furthermore, anisotropy and optimality can be simultaneously maximized. The entanglement decays rapidly, implicating it as a situational by-product rather than a fundamental driver within the avian compass. In magnetic fields of higher intensity, the relative orientation of radicals in [F center dot- W center dot+] is less important than for the geomagnetic field. Published under license by AIP Publishing.