Mevalonate pyrophosphate decarboxylase (MPD) in mouse liver was purified by affinity chromatography. The purified enzyme was a homodimer of 46-kDa subunits and had an isoelectric point of 5.0. Kinetic analysis revealed an apparent Km value of 10 μM for mevalonate pyrophosphate. The enzyme required ATP as a phosphate acceptor and Mg as a divalent cation, which could be substituted with Mn or Co. Its optimum pH was 4.0—7.0. A comparison with MPD from various other sources revealed the mouse MPD to have essentially the same properties as rat MPD, expect for the optimum pH range. An excess of rabbit anti-rat MPD antibody deleted approximately 80% of the MPD activity in the crude extract of mouse liver. These results suggested that the homodimer of 46-kDa subunits represents the major active form of MPD in mice.
通过亲和层析法纯化了小鼠肝脏中的
焦磷酸甲羟
戊酸脱羧酶(
MPD)。纯化的酶是 46 kDa 亚基的同源二聚体,等电点为 5.0。动力学分析表明,
焦磷酸甲羟
戊酸的表观 Km 值为 10 μ<小>M小>。该酶需要
ATP 作为
磷酸受体,Mg 作为二价阳离子,可以用 Mn 或 Co 取代。与其他不同来源的
MPD 进行比较后发现,小鼠
MPD 除最适 pH 值范围外,与大鼠
MPD 具有基本相同的特性。过量的兔抗大鼠
MPD 抗体会破坏小鼠肝脏粗
提取物中约 80% 的
MPD 活性。这些结果表明,46-kDa 亚基的同源二聚体代表了小鼠
MPD 的主要活性形式。