Hasan N, Nester E W
J Biol Chem. 1978 Jul 25;253(14):4999-5004.
Dehydroquinate synthase, the enzyme which catalyzes the conversion of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate (DAHP) to 5-dehydroquinate, has been purified from Bacillus subtilis in association with chorismate synthase and NADPH-dependent flavin reductase. The enzyme was only active when associated with chorismate synthase, whereas the flavin reductase could be separated from the complex with retention of dehydroquinate synthase activity. The enzyme requires NAD and either Co2+ or Mn2+ for maximal activity. The activity was completely inhibited by EDTA. The Km of the enzyme for DAHP, NAD, and Co2+ were estimated to be 1.3 X 10(-4), 5.5 X 10(-5), and 5.5 X 10(-5) M, respectively. Enzyme activity was completely inhibited by NADH and the inhibition was not reversed by the addition of NAD, NADPH and NADP were not inhibitory. The enzyme was unstable to heat and lost all activity at 55 degrees C. A protein fraction which did not adsorb to phosphocellulose was found to inhibit the enzyme.
脱氢奎尼酸合酶可催化7-磷酸-3-脱氧-D-阿拉伯庚酮糖酸（DAHP）转化为5-脱氢奎尼酸，该酶已从枯草芽孢杆菌中分离出来，它与分支酸合酶和NADPH依赖性黄素还原酶相关联。该酶只有在与分支酸合酶结合时才具有活性，而黄素还原酶可以从复合物中分离出来，同时保留脱氢奎尼酸合酶的活性。该酶需要NAD以及Co2+或Mn2+才能达到最大活性。其活性完全被EDTA抑制。该酶对DAHP、NAD和Co2+的Km值分别估计为1.3×10(-4)、5.5×10(-5)和5.5×10(-5)M。酶活性完全被NADH抑制，且添加NAD不能逆转这种抑制作用，NADPH和NADP没有抑制作用。该酶对热不稳定，在55℃时会失去所有活性。发现一种不吸附于磷酸纤维素的蛋白质组分可抑制该酶。
