Sand O
Comp Biochem Physiol B. 1984;79(3):473-9. doi: 10.1016/0305-0491(84)90408-5.
Two forms of pyruvate kinase, PK I and PK II, have been demonstrated in flounder liver. PK I, purified 991-fold to a specific activity of 105 units per mg of protein, has an unusually high molecular weight of about 2 X 10(6). PK II, purified 172-fold to a specific activity of 16.5 units per mg of protein, has a molecular weight of 210,000 when determined on a sucrose gradient but of 300,000 when derived from gel chromatography. PK I and PK II differ in sensitivity to the inhibitor L-phenylalanine, a fact which is used to evaluate the amount of each of them in a mixture. pH optimum for both forms is 6-6.6. PK I and PK II behave different in an Arrhenius plot--PK II showing a transition at 21 degrees C.
在比目鱼肝脏中已证实存在两种形式的丙酮酸激酶，即PK I和PK II。PK I经纯化991倍，比活性达到每毫克蛋白质105单位，其分子量异常高，约为2×10⁶ 。PK II经纯化172倍，比活性为每毫克蛋白质16.5单位，在蔗糖梯度中测定时分子量为210,000，但从凝胶色谱法得出的分子量为300,000。PK I和PK II对抑制剂L - 苯丙氨酸的敏感性不同，这一事实可用于评估混合物中它们各自的含量。两种形式的最适pH均为6 - 6.6。在阿累尼乌斯图中，PK I和PK II表现不同——PK II在21℃出现转变。
