Rapid and sensitive measurement of dissolved gases by permeable membrane mass-spectrometry.

闪光引起的析氧使用渗透膜质谱仪测量。通过透气膜（0.024 mm厚，硅橡胶; General Electric，USA）将放出的气体引入四极质量分析仪（MSQ 15 OA; ULVAC，Japan）。将冻干的PS II膜的纸盘轻轻浸入0.3- 1.5ml的50 mM Hepes/NaOH（pH 6.8）中，其已经用Ar气冲洗。反应室（直径1cm）用气密的丙烯酸活塞盖封闭。在25 ℃下于黑暗中孵育5 - 10 min后，在20-30 s的黑暗间隔下，在30-50 J，t_<1/2> = 0.03 ms; Sugawara Kenkyusho，Japan的闪光灯下，在32 m/e的离子峰处测量氧释放。当样品溶液的厚度为0.1 mm时，闪光诱导的氧释放信号的半衰减时间约为2 s。在连续条件下，再悬浮的冻干PS II膜的氧释放活性为0.27 mmol氧（mg Chl）·<-1>h·<-1>。 ...更多信息 光，这是70%的控制PS II膜。我们研究了冷冻干燥对氧气释放振荡模式的影响。对照PS II膜的氧释放在第三次闪光时最大，并且以4次闪光的周期振荡。而在Hepes缓冲液中浸泡的PS Ⅱ膜在第6次闪蒸时放出的氧最多，表明水氧化酶在冻干过程中明显还原到S<-2>态。预照射后，冻干膜的析氧量与对照膜一样振荡。此外，预光照和冻干PS II膜的失命中概率和双命中概率以及析氧模式的S_1/（S_0+S_1）与对照膜相似。冷冻干燥降低了水氧化酶，并且只有在酶中的高亲和力位点存在结合水的情况下，两个光子才使酶返回到S_0状态。少

Flash induced oxygen evolution was measured using a permeable membrane-mass spectrometer. Evolved gases were introduced through a gas-permeable membrane (0.024 mm thick, silicone rubber; General Electric, USA) to a quadrupole mass analyzer (MSQ 15OA; ULVAC, Japan). The paper disk of the lyophillized PS II membranes was gently immersed in 0.3-1.5 ml of 50 mM Hepes/NaOH (pH 6.8) which had been flushed with Ar gas. The reaction chamber (1 cm in diameter) was closed with a gas-tight, acrylic piston lid. After incubation in the dark for 5 to 10 min at 25ﾟC, the oxygen evolution was measured at the ion peak of 32 m/e under a Xe flash (30-50 J, t_<1/2> = 0.03 ms; Sugawara Kenkyusho, Japan) at dark intervals of 20-30 s. The half-decay time of the signal of the flash induced oxygen evolution was about 2 s when the thickness of the sample solution was 0.1 mm. The oxygen-evolving activity of the resuspended lyophillized PS II membranes was 0.27 mmol of oxygen (mg Chl)^<-1>h^<-1> under continuous … More light which was 70% that of the control PS II membranes. We examined the effect of lyophillization on the oscillation pattern of oxygen evolution by flash illuminations. The oxygen evolution of the control PS II membranes was maximal at the third flash and oscillated with a period of 4 flashes. The lyophillized PS II membranes which were immersed in Hepes buffer, however, showed the maximal evolution of oxygen at the sixth flash, indicating the water-oxidizing enzyme was apparently reduced to "S_<-2> state" by lyophillization. After preillumination the oxygen evolution of the lyophillized membranes oscillated as the control membranes did. Moreover, the miss-hit and double-hit probabilities and S_1/(S_0+S_1) for the oxygen evolution pattern of the lyophillized and preilluminated PS II membranes were similar to those of the control membranes. The lyophillization reduces the water-oxidizing enzyme, and the two photons return the enzyme to the S_0 state only in the presence of the water bound the the high-affinity sites in the enzyme. Less