McDaniel H G, Siu P M
J Bacteriol. 1972 Jan;109(1):385-90. doi: 10.1128/jb.109.1.385-390.1972.
Phosphoenolpyruvate (PEP) carboxylase was purified over 400-fold from Plasmodium berghei. The purified enzyme was stable in 0.4 m potassium phosphate buffer (pH 7.4) containing 0.5 m glucose, 1 mm ethylenediaminetetraacetic acid (EDTA), and 1 mm MgCl(2). It had a molecular weight of 280,000 determined by sucrose density gradient centrifugation in this buffer, but it aggregated and was unstable in the presence of different salts or a more dilute solution of potassium phosphate. The K(m) for PEP was 2.6 mm and that for Mg(2+) was 1.3 mm. The K(m) for bicarbonate was 2 mm. Citrate, nucleotides, and EDTA inhibited the PEP carboxylase of P. berghei by decreasing the concentration of free magnesium ions, but acetyl-coenzyme A, fructose-1,6-diphosphate, and aspartate did not influence its activity. A chloroquine concentration of 1.8 x 10(-4)m inhibited the enzyme 50%.
磷酸烯醇式丙酮酸（PEP）羧化酶从伯氏疟原虫中纯化出来，纯化倍数超过400倍。纯化后的酶在含有0.5 M葡萄糖、1 mM乙二胺四乙酸（EDTA）和1 mM氯化镁（MgCl₂）的0.4 M磷酸钾缓冲液（pH 7.4）中稳定。在该缓冲液中通过蔗糖密度梯度离心法测定其分子量为280,000，但在存在不同盐类或更稀的磷酸钾溶液时会聚集且不稳定。PEP的Kₘ为2.6 mM，Mg²⁺的Kₘ为1.3 mM。碳酸氢盐的Kₘ为2 mM。柠檬酸盐、核苷酸和EDTA通过降低游离镁离子浓度来抑制伯氏疟原虫的PEP羧化酶，但乙酰辅酶A、果糖-1,6-二磷酸和天冬氨酸不影响其活性。浓度为1.8×10⁻⁴ M的氯喹抑制该酶活性达50%。
