Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
Biophys J. 2010 Feb 3;98(3):488-92. doi: 10.1016/j.bpj.2009.10.025.
Spectral tuning in the photoactive yellow protein (PYP) is investigated by performing gas-phase absorption measurements on a PYP-model chromophore with two water molecules hydrogen-bonded to it. The photoabsorption maximum shows an unusually large blue shift of 0.71 eV in going from the bare to the hydrogen-bonded chromophore. It is concluded that several interactions within the PYP protein are mutually cancelling each other, yielding an absorption maximum that is close to the absorption maximum of the bare chromophore. The system breaks apart upon photoexcitation in the gas phase by releasing the two water molecules, leaving the chromophore itself intact. The hydrogen-bonding interactions thus play an important role in stabilizing the gas phase chromophore against photofragmentation. The relaxation dynamics for the breakup process was also studied, and the timescale of relaxation via fragmentation was found to be < 25 ns.
对光致变色黄色蛋白（PYP）的光谱调谐进行了研究，方法是对与两个水分子氢键结合的 PYP 模型发色团进行气相吸收测量。从裸露的发色团到氢键结合的发色团，光吸收最大值显示出异常大的 0.71 电子伏特的蓝移。得出的结论是，PYP 蛋白内的几个相互作用相互抵消，使得吸收最大值接近于裸露发色团的吸收最大值。在气相中光激发时，该系统通过释放两个水分子而分裂，使发色团本身保持完整。因此，氢键相互作用在稳定气相发色团免受光碎裂方面起着重要作用。还研究了断裂过程的弛豫动力学，并且发现通过碎裂的弛豫时间尺度<25 ns。
