在光热素的逆反应后,螺旋形状何时恢复?
Yuki Kawaguchi1, Yusuke Nakasone, Kazunori Zikihara
1Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|June 12, 2010
概括
展开的Phot1LOV2-linker蛋白在键断裂后慢慢重新折叠,需要13 ms. 这种蛋白质折叠速度明显低于溶液中典型的α螺旋形成.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 摄影化学的使用.
背景情况:
- 像Phot1LOV2这样的光受体对光感应至关重要.
- 链接区域连接功能域并影响蛋白质构成.
- 了解光诱导事件后的蛋白质动态是光感受器功能的关键.
研究的目的:
- 为了研究 Phot1LOV2-linker 在对应键断裂后的折叠动力学.
- 为了将Phot1LOV2-linker的重新折叠率与已知的蛋白质折叠率进行比较.
主要方法:
- 通过光化学激活Phot1LOV2链接器.
- 时间解析的光谱技术用于监测形状变化.
- 动力分析以确定折叠时间常数.
主要成果:
- 囊 - 黄共价键的破坏启动了链接的展开.
- 展开的Phot1LOV2链接器以13 ms的特征时间常数重新折叠.
- 这种重新折叠速度比溶液中的α螺旋形成慢大约1万倍.
结论:
- 在光激活后,Phot1LOV2-linker表现出缓慢的形状动态.
- 链接器的缓慢重新折叠可能在信号传播或光感受器中的调节中发挥作用.
- 这些发现为光感应蛋白质的机械特性提供了洞察力.
相关概念视频
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:22Photosystem II
The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ultimately to photosystem I (PSI) through the electron transport chain. The pigments responsible for caputirng the light energy in photosystems include chlorophyll a, chlorophyll b, and carotenoids.
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
01:15The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...
01:27Photosystem I
Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...