Rivoal J, Ricard B, Pradet A
Institut National de la Recherche Agronomique, Centre de Recherches de Bordeaux, Villenave d'Ornon, France.
Eur J Biochem. 1990 Dec 27;194(3):791-7. doi: 10.1111/j.1432-1033.1990.tb19471.x.
Pyruvate decarboxylase(PyrDC) was purified from rice bran to a specific activity of 1 mu kat/mg and partially characterized. The holoenzyme is a tetramer of two types of subunits with molecular masses 64 kDa and 62 kDa. Purified rice PyrDC exhibits positive cooperative kinetics with respect to pyruvate and functions with a significant lag phase. When compared to other plant PyrDC, the lag phase was shorter at low pyruvate concentrations and the S0.5 was smaller. The optimum pH (6.25) was also less acidic and the enzyme retained 30% of its maximal activity at neutral pH. In contrast to other plant PyrDC, rice PyrDC could be active at the onset of anoxia and would be activated by small changes in pyruvate concentration.
丙酮酸脱羧酶（PyrDC）从米糠中纯化出来，比活性达到1微 katal/毫克，并对其进行了部分特性鉴定。全酶是由分子量分别为64 kDa和62 kDa的两种亚基组成的四聚体。纯化后的水稻PyrDC对丙酮酸呈现正协同动力学，且具有明显的延迟期。与其他植物的PyrDC相比，在低丙酮酸浓度下延迟期更短，半饱和常数（S0.5）更小。最适pH值（6.25）的酸性也较弱，该酶在中性pH值下仍保留其最大活性的30%。与其他植物的PyrDC不同，水稻PyrDC在缺氧开始时就具有活性，并且会被丙酮酸浓度的微小变化所激活。
