Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Schlossplatz 8, 48143, Münster, Germany.
Photosynth Res. 2018 Aug;137(2):281-293. doi: 10.1007/s11120-018-0502-3. Epub 2018 Mar 28.
The absolute amount of plastocyanin (PC), ferredoxin-NADP-oxidoreductase (FNR), hydrogenase (HYDA1), and ferredoxin 5 (FDX5) were quantified in aerobic and anaerobic Chlamydomonas reinhardtii whole cells using purified (recombinant) proteins as internal standards in a mass spectrometric approach. Quantified protein amounts were related to the estimated amount of PSI. The ratios of PC to FNR to HYDA1 to FDX5 in aerobic cells were determined to be 1.4:1.2:0.003:0. In anaerobic cells, the ratios changed to 1.1:1.3:0.019:0.027 (PC:FNR:HYDA1:FDX5). Employing sodium dithionite and methyl viologen as electron donors, the specific activity of hydrogenase in whole cells was calculated to be 382 ± 96.5 μmolH min mg. Importantly, these data reveal an about 70-fold lower abundance of HYDA1 compared to FNR. Despite this great disproportion between both proteins, which might further enhance the competition for electrons, the alga is capable of hydrogen production under anaerobic conditions, thus pointing to an efficient channeling mechanism of electrons from FDX1 to the HYDA1.
采用纯化（重组）蛋白作为内参标准，通过质谱法对好氧和厌氧莱茵衣藻全细胞中的质体蓝素（PC）、铁氧还蛋白-NADP 氧化还原酶（FNR）、氢化酶（HYDA1）和铁氧还蛋白 5（FDX5）的绝对含量进行了定量。定量的蛋白量与 PSI 的估计量相关。在好氧细胞中，PC 与 FNR 与 HYDA1 与 FDX5 的比值分别为 1.4:1.2:0.003:0. 在厌氧细胞中，比值分别变为 1.1:1.3:0.019:0.027（PC:FNR:HYDA1:FDX5）。采用连二亚硫酸钠和甲紫精作为电子供体，计算出全细胞氢化酶的比活性为 382±96.5 μmolH min mg。重要的是，这些数据表明与 FNR 相比，HYDA1 的丰度大约低 70 倍。尽管这两种蛋白质之间存在巨大的不成比例，这可能进一步加剧了电子竞争，但藻类仍能够在厌氧条件下产生氢气，这表明从 FDX1 到 HYDA1 的电子有效转移机制。
