Reaction mechanism of phosphoribulokinase from a cyanobacterium, Synechococcus PCC7942

被引：0
作者：
Akira Wadano
Keisuke Nishikawa
Tomohiro Hirahashi
Ryohei Satoh
Toshio Iwaki
机构：
[1] Osaka Prefecture University,Department of Applied Biochemistry
来源：
Photosynthesis Research | 1998年 / 56卷
关键词：
control coefficient; cyanobacteria; phosphoribulokinase; reaction mechanism;
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摘要：
The dependence of the activity of phosphoribulokinase isolated from a cyanobacterium, Synechococcus PCC7942, on Mg2+ showed that its real substrates were Mg-ATP and free D-ribulose 5-phosphate. On the basis of results of kinetic inhibition studies and previously reported result of affinity chromatography, an ordered bi bi mechanism in which Mg-ATP binds before ribulose 5-phosphate is proposed. The Km values for ATP and D-ribulose 5-phosphate were 0.09 and 0.27 mM, respectively. Ki values of ADP and D-ribulose 1,5-bisphosphate were 0.32 and 10.0 mM, respectively. Inhibition constants Ki1 and Ki2 for 6-phosphogluconate were 9.3 and 0.49 mM. Kia was 0.13 mM. New kinetics on PRK gave higher control coefficient than the kinetics on Spinach PRK did in the model with PRK activity from 175 to 1000 µmol min−1 mg−1 chl.
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页码：27 / 33
页数：6
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