Potent inhibition of ribulose-bisphosphate carboxylase by an oxidized impurity in ribulose-1,5-bisphosphate
Potent inhibition of ribulose-bisphosphate carboxylase by an oxidized impurity in ribulose-1,5-bisphosphate
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DOI：
10.1104/pp.117.3.1059
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发表时间：
1998-07-01
期刊：
影响因子：
7.4
通讯作者：
Andrews, TJ
中科院分区：
文献类型：
--
作者：
Kane, HJ;Wilkin, JM;Andrews, TJ
D-核酮糖-1，5-二磷酸（核酮糖-P-2）在合成和/或储存过程中的氧化产生D-甘油-2，3-戊二酮糖-1，5-二磷酸（戊二酮糖-P-2），其是菠菜（Spinacia oleracea L.）核酮糖-P-2羧化酶/加氧酶（Rubisco）。戊二糖-P-2的污染程度不同，导致Rubisco测定时程中观察到的Rubisco活性下降，在不同的核酮糖-P-2制剂之间变化。对于某些核酮糖-P-2制剂，这种化合物可能是下降的主要原因，远远超过催化副产物D-木酮糖-1，5-二磷酸的重要性。与木酮糖-1，5-二磷酸不同，戊二糖-P-2似乎不是在饱和CO2浓度下野生型Rubisco催化的显著副产物，其在核酮糖-P-2的冷冻储存期间缓慢产生，即使在低pH下，在室温下在Rubisco测定缓冲液中更快速地产生，并且在用Cu 2+故意氧化核酮糖-P-2时特别快速。通过排除过渡金属和O-2来防止其形成。戊二糖-P-2是不稳定的，并衰变为各种其他抑制性较低的化合物，特别是在一些缓冲液的存在下。然而，它形成了一个紧密的，稳定的复合物与氨甲酰化菠菜Rubisco，这可以通过凝胶过滤分离，大概是因为它的结构模拟的england中间体的Rubisco催化。Rubisco催化戊二糖-P-2被H2 O2裂解，产生P-乙醇酸。
Oxidation of D-ribulose-1,5-bisphosphate (ribulose-P-2) during synthesis and/or storage produces D-glycero-2,3-pentodiulose-1,5-bisphosphate (pentodiulose-P-2), a potent slow, tight-binding inhibitor of spinach (Spinacia oleracea L.) ribulose-P-2 carboxylase/ oxygenase (Rubisco). Differing degrees of contamination with pentodiulose-P-2 caused the decline in Rubisco activity seen during Rubisco assay time courses to vary between different preparations of ribulose-P-2. With some ribulose-P-2 preparations, this compound can be the dominant cause of the decline, far exceeding the significance of the catalytic by-product, D-xylulose-1,5-bisphosphate. Unlike xylulose-1,5-bisphosphate, pentodiulose-P-2 did not appear to be a significant by-product of catalysis by wild-type Rubisco at saturating CO2 concentration, it was produced slowly during frozen storage of ribulose-P-2, even at low pH, more rapidly in Rubisco assay buffers at room temperature, and particularly rapidly on deliberate oxidation of ribulose-P-2 with CU2+. Its formation was prevented by the exclusion of transition metals and O-2. Pentodiulose-P-2 was unstable and decayed to a variety of other less-inhibitory compounds, particularly in the presence of some buffers. However, it formed a tight, stable complex with carbamylated spinach Rubisco, which could be isolated by gel filtration, presumably because its structure mimics that of the enediol intermediate of Rubisco catalysis. Rubisco catalyzes the cleavage of pentodiulose-P-2 by H2O2, producing P-glycolate.