Viil Juta, Ivanova Hiie, Pärnik Tiit
Division of Plant Physiology, Institute of Agriculture and Environment, Estonian Agricultural University, 76902 Harku, Estonia.
Photosynth Res. 2006 Jun;88(3):357-66. doi: 10.1007/s11120-006-9050-3. Epub 2006 Jun 9.
Oxygen may enhance CO2-saturated photosynthesis in intact leaves, which display the Warburg effect when illuminated at the current atmospheric level of CO2 and O2, of about 350 microl l(-1) and 21%, respectively. The magnitude of the stimulation depends on irradiance. The K(M)(O2) of the stimulation is 128 microM (10.6% O2). Maximum enhancement in wheat leaves is 6.1 and 5.3 micromol m(-2) s(-1 )under 27.9 and 18.7 mW cm(-2), respectively, corresponding to a 25-30% increase in the ribulose 1,5-bisphosphate (RuBP) turnover rate if compared with O2-free ambient gas phase. The stimulation appears in 5-10 s after a sharp increase in O2. In response to a decrease in O2, the new stabilized rate is reached in 5-7 min. The stimulation does not involve any increase in the activity of Rubisco. The effect correlates with increased concentration of RuBP. Oxygen enhances CO2-saturated photosynthesis by acting as a terminal electron acceptor in the photosynthetic electron transport. The magnitude of the effect may be adopted as an index of the pseudocyclic photophosphorylation in vivo.
在完整叶片中，氧气可能会增强二氧化碳饱和状态下的光合作用。当在当前大气二氧化碳和氧气水平（分别约为350微升升⁻¹和21%）下光照时，完整叶片会表现出瓦伯格效应。刺激的程度取决于辐照度。刺激作用的米氏常数（K(M)(O2)）为128微摩尔（10.6%氧气）。在27.9和18.7毫瓦厘米⁻²的光照强度下，小麦叶片的最大增强量分别为6.1和5.3微摩尔米⁻²秒⁻¹，与无氧气的环境气相相比，这相当于核酮糖-1,5-二磷酸（RuBP）周转速率提高了25 - 30%。在氧气急剧增加后5 - 10秒内会出现这种刺激作用。响应氧气减少时，在5 - 7分钟内达到新的稳定速率。这种刺激作用并不涉及 Rubisco 活性的任何增加。该效应与 RuBP 浓度的增加相关。氧气通过在光合电子传递中作为末端电子受体来增强二氧化碳饱和状态下的光合作用。该效应的大小可作为体内假循环光合磷酸化的一个指标。
