Mücke U, König S, Hübner G
Department of Biochemistry and Biotechnology, Martin-Luther-University, Halle-Wittenberg, Halle, Germany.
Biol Chem Hoppe Seyler. 1995 Feb;376(2):111-7. doi: 10.1515/bchm3.1995.376.2.111.
Pyruvate decarboxylase (PDC) was purified from pea seeds. The catalytically active holoenzyme is an oligomer of two types of subunits with molecular masses of about 65 kDa and 68 kDa, respectively. The active enzyme is a mixture of tetramers, octamers and even higher oligomers. These differences in the quaternary structure compared with PDC from yeast (tetramer) do not result in a different kinetic behaviour. The activity of pea PDC as well as that of yeast PDC is regulated by its substrate pyruvate resulting in a sigmoid shape of the v/S-plot. At the optimum pH of 6.0 a S0.5-value of 1 mM pyruvate is found that increases with rising pH and increasing concentrations of phosphate. The substrate analogue activator pyruvamide activates the enzyme resulting in a hyperbolic v/S-plot. The stability of PDC from pea seeds in solution is about one order of magnitude higher than that of yeast PDC. Despite the described similarities of the two enzymes no significant cross reactivity of the anti-pea PDC antibody with the enzyme from yeast occurs.
丙酮酸脱羧酶（PDC）从豌豆种子中纯化得到。具有催化活性的全酶是由两种亚基组成的寡聚体，其分子量分别约为65 kDa和68 kDa。活性酶是四聚体、八聚体甚至更高寡聚体的混合物。与酵母中的PDC（四聚体）相比，这种四级结构上的差异并未导致不同的动力学行为。豌豆PDC以及酵母PDC的活性都受其底物丙酮酸的调节，从而使v/S曲线呈S形。在最适pH 6.0时，丙酮酸的S0.5值为1 mM，该值随pH升高和磷酸盐浓度增加而增大。底物类似物激活剂丙酮酰胺可激活该酶，从而产生双曲线型的v/S曲线。豌豆种子中的PDC在溶液中的稳定性比酵母PDC高约一个数量级。尽管这两种酶有上述相似之处，但抗豌豆PDC抗体与酵母中的酶没有明显的交叉反应。
