Servaites J C
Department of Agronomy, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1978 Jan;61(1):62-7. doi: 10.1104/pp.61.1.62.
The occurrence of photorespiration in soybean (Glycine max [L.] Merr.) leaf cells was demonstrated by the presence of an O(2)-dependent CO(2) compensation concentration, a nonlinear time course for photosynthetic (14)CO(2) uptake at low CO(2) and high O(2) concentrations, and an O(2) stimulation of glycine and serine synthesis which was reversed by high CO(2) concentration. The compensation concentration was a linear function of O(2) concentration and increased as temperature increased. At atmospheric CO(2) concentration, 21% O(2) inhibited photosynthesis at 25 C by 27%. Oxygen inhibition of photosynthesis was competitive with respect to CO(2) and increased with increasing temperature. The Km (CO(2)) of photosynthesis was also temperature-dependent, increasing from 12 mum CO(2) at 15 C to 38 mum at 35 C. In contrast, the Ki (O(2)) was similar at all temperatures. Oxygen inhibition of photosynthesis was independent of irradiance except at 10 mm bicarbonate and 100% O(2), where inhibition decreased with increasing irradiance up to the point of light saturation of photosynthesis. Concomitant with increasing O(2) inhibition of photosynthesis was an increased incorporation of carbon into glycine and serine, intermediates of the photorespiratory pathway, and a decreased incorporation into starch. The effects of CO(2) and O(2) concentration and temperature on soybean cell photosynthesis and photorespiration provide further evidence that these processes are regulated by the kinetic properties of ribulose-1,5-diphosphate carboxylase with respect to CO(2) and O(2).
大豆（Glycine max [L.] Merr.）叶片细胞中光呼吸的发生通过以下现象得以证明：存在依赖于O₂的CO₂补偿浓度、在低CO₂和高O₂浓度下光合（¹⁴）CO₂吸收的非线性时间进程，以及O₂对甘氨酸和丝氨酸合成的刺激作用，而高CO₂浓度可逆转这种刺激作用。补偿浓度是O₂浓度的线性函数，并随温度升高而增加。在大气CO₂浓度下，21%的O₂在25℃时抑制光合作用达27%。O₂对光合作用的抑制作用相对于CO₂具有竞争性，且随温度升高而增强。光合作用的Km（CO₂）也与温度有关，从15℃时 的12 μmol CO₂增加到35℃时的38 μmol。相比之下，Ki（O₂）在所有温度下都相似。除了在10 mmol碳酸氢盐和100% O₂条件下，O₂对光合作用的抑制作用与光照强度无关，在该条件下，抑制作用随光照强度增加直至光合作用达到光饱和点而降低。伴随着O₂对光合作用抑制作用的增强，碳向光呼吸途径的中间产物甘氨酸和丝氨酸中的掺入增加，而向淀粉中的掺入减少。CO₂和O₂浓度以及温度对大豆细胞光合作用和光呼吸的影响进一步证明，这些过程受核酮糖-1,5-二磷酸羧化酶相对于CO₂和O₂的动力学特性调控。
