Group Research and Development, Tate and lyle Ltd., P.O. Box 68, RG6 2BX, Reading, UK.
Planta. 1975 Jan;124(2):153-8. doi: 10.1007/BF00384757.
The effects of 3C intermediates of the photosynthetic carbon reduction (PCR) cycle (glyceraldehyde 3 phosphate [G3P], dihydroxyacetone phosphate and 3 phosphoglyceric acid) on the activity of phosphoenol pyruvate (PEP) carboxylase from Pennisetum purpureum (a C4 plant) have been investigated. Addition of these compounds, at concentrations greater than about 3 mM, to standard assay mixtures (5 mM concentrations of PEP, HCO3 (-) and Mg(2+)) reduced the observed activity. The extent of inhibition was greater at lower (<5 mM) concentration of Mg(2+). G3P was the most potent inhibitor. During studies of saturation kinetics with PEP as variable substrate it was found that addition of these 3C compounds (2mM) reduced the sigmoid nature of Michaelis-Menten plots and reduced the value of n obtained from Hill plots from about 3 to near one. The results are disussed in terms of the possible regulation of C4 photosynthesis by intermediates of the PCR cycle which are easily leaked from chloroplasts.
已经研究了光合作用碳还原（PCR）循环的 3C 中间体（甘油醛 3 磷酸[G3P]、二羟丙酮磷酸和 3 磷酸甘油酸）对黍属（C4 植物）的磷酸烯醇丙酮酸（PEP）羧激酶活性的影响。在标准测定混合物（PEP、HCO3（-）和 Mg（2+）浓度为 5mM）中添加这些浓度大于约 3mM 的化合物会降低观察到的活性。在较低的（<5mM）Mg（2+）浓度下，抑制程度更大。G3P 是最有效的抑制剂。在以 PEP 为可变底物的饱和动力学研究中发现，添加这些 3C 化合物（2mM）降低了米氏作图的 S 形特征，并将从 Hill 作图获得的 n 值从约 3 降低到接近 1。结果根据 PCR 循环中间产物可能通过容易从叶绿体漏出而对 C4 光合作用的调节进行了讨论。
