Oka Yoshimi, Quintes Florian, Yoshikawa Yuri, Fujiwara Motoyasu, Maeda Kiminori, Weber Stefan, Inoue Katsuya
Research Promotion Institute, Oita University, Oita-shi, Oita, Japan.
International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM²), Chirality Research Center (CResCent), and Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima-shi, Hiroshima, Japan.
Commun Chem. 2025 Jul 9;8(1):203. doi: 10.1038/s42004-025-01596-x.
The mechanism by which cryptochrome (CRY) proteins are capable of sensing weak magnetic fields (e.g., the geomagnetic field: ~50 μT) was suggested to be mediated by spin-correlated radical pairs (SCRPs) comprising a flavin adenine dinucleotide (FAD) radical and a tryptophan (Trp) radical which are formed simultaneously by light-induced electron transfer (ET). Here, we provide evidence for direct photoinduced ET that leads to long-lived SCRPs comprising a flavin (Fl) radical and a guanine (G) radical in flavin-tethered single- and double-stranded DNA oligomers by using time-resolved electron paramagnetic resonance (TREPR) spectroscopy. Transient absorption (TA) spectroscopy and its magnetic field effect (MFE) identified RP generation via a triplet-state precursor, in contrast to RP generation via a singlet-state precursor in CRY. Our findings of RPs in Fl-DNA oligomers having microsecond-long lifetimes and capable of exerting a large MFE at room temperature may significantly impact on our understanding of biological magnetoreception.
隐花色素（CRY）蛋白能够感知弱磁场（例如，地磁场：~50 μT）的机制被认为是由包含黄素腺嘌呤二核苷酸（FAD）自由基和色氨酸（Trp）自由基的自旋相关自由基对（SCRP）介导的，这些自由基对是通过光诱导电子转移（ET）同时形成的。在此，我们通过使用时间分辨电子顺磁共振（TREPR）光谱，提供了直接光诱导电子转移的证据，该电子转移导致在黄素连接的单链和双链DNA寡聚物中形成包含黄素（Fl）自由基和鸟嘌呤（G）自由基的长寿命SCRP。瞬态吸收（TA）光谱及其磁场效应（MFE）确定了通过三重态前体产生自由基对，这与CRY中通过单重态前体产生自由基对形成对比。我们在具有微秒级长寿命且能够在室温下产生大磁场效应的Fl-DNA寡聚物中发现自由基对，这可能会对我们对生物磁感受的理解产生重大影响。
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