Ultraviolet Resonance Raman Study on Protein Structure Dynamics of Cytochrome c Oxidase

研制了一种高性能的生物用紫外共振拉曼光谱仪。在一台1260 mm的单光谱仪上安装了一个日盲增强型电荷耦合器件，该光谱仪具有200 nm闪耀、3600沟槽/mm的光栅。对无模氩离子激光器的488 nm输出进行倍频，获得244 nm紫外光，用于共振拉曼激发。该拉曼光谱仪已被应用于细胞色素c氧化酶，以探测酪氨酸和色氨酸残基在氧化还原和连接状态变化时的结构变化。在一氧化碳或氰化物存在和不存在的情况下，该酶的静息氧化、完全还原和混价形式已被测量。可见，血红素a和/或铜A的氧化还原改变引起酪氨酸和色氨酸残基的最显著变化，而与血红素a_3的连接和血红素a_3和/或铜B的氧化还原改变对蛋白质结构的影响较小。为分析细胞色素C氧化酶的时间分辨紫外共振拉曼光谱奠定了基础。

A high performance ultraviolet resonance Raman spectrophotometer for biological applications has been constructed. A solar-blind intensified charge-coupled device was attached to a 1260 mm single spectrograph with a 200 nm-blazed, 3600 grooves/mm grating. The 488 nm output of a mode-lacked argon ion laser was frequency doubled to obtain 244nm UV light for resonance Raman excitation. This Raman spectrophotometer has been applied to cytochrome c oxidase to probe structural changes of tyrosine and tryptophan residues upon redox and ligation-state changes. Resting oxidized, fully-reduced and mixed-valence forms of the enzyme in the presence and absence of carbonmonoxide or cyanide have been measured. It became evident that a redox change of heme a and / or Cu_A induced most prominent changes on tyrosine and tryptophan residues while ligation to heme a_3 and redox change of heme a_3 and / or Cu_B less affected the protein structures. Basic data to analyze time-resolved UV resonance Raman spectra of cytochrome c oxidase have been established.