Isozyme composition and phosphorylation of brain phosphofructokinase.
Isozyme composition and phosphorylation of brain phosphofructokinase.
复制标题
脑磷酸果糖激酶的同工酶组成和磷酸化。
DOI：
10.1016/0003-9861(84)90016-x
复制
发表时间：
1984
影响因子：
3.9
通讯作者：
Kemp,RG
中科院分区：
文献类型：
--
作者：
Foe,LG;Kemp,RG
通过亲和层析和凝胶过滤的快速程序将兔脑磷酸果糖激酶纯化至同质。该酶由三种磷酸果糖激酶亚基 C、A 和 B 类型的杂合体组成。这些亚基的分子量分别为 86,000、84,000 和 80,000；它们以大约 5:4:1.5 的比例存在于脑磷酸果糖激酶中。从兔脑中分离出来的酶每摩尔亚基含有 0.16-0.18 摩尔磷酸盐；在环 AMP 依赖性蛋白激酶催化亚基存在的情况下，每摩尔亚基可掺入另一个 0.4-0.5 摩尔磷酸盐。果糖 2,6-二磷酸或 AMP 会增加磷酸化的初始速率，柠檬酸盐或高浓度硫酸铵会降低磷酸化的初始速率。所有三种亚基类型均在体外被磷酸化，并且每个亚基上的磷酸化位点对每个亚基末端区域的胰蛋白酶切割敏感。然而，在存在硫酸铵的情况下，这些位点在体外显示出不同的相对磷酸化率。脑磷酸果糖激酶的体外磷酸化对比活性、ATP 抑制或果糖 2,6-二磷酸激活没有影响。
Rabbit brain phosphofructokinase was purified to homogeneity by a rapid procedure involving affinity chromatography and gel filtration. The enzyme consists of hybrids of the three phosphofructokinase subunit types C, A, and B. The molecular weights of these subunits are 86,000, 84,000, and 80,000, respectively; they are present in brain phosphofructokinase in a ratio of approximately 5:4:1.5. The enzyme as isolated from rabbit brain contains 0.16–0.18 mol phosphate per mole of subunit; another 0.4–0.5 mol phosphate per mole subunit can be incorporatedin vitroin the presence of the catalytic subunit of cyclic AMP-dependent protein kinase. The initial rate of phosphorylation is increased by fructose 2,6-bisphosphate or AMP and decreased by citrate or high concentrations of ammonium sulfate. All three subunit types are phosphorylatedin vitro, and the phosphorylation site on each subunit is sensitive to cleavage by trypsin at a terminal region of each subunit. However, these sites show different relative rates of phosphorylationin vitroin the presence of ammonium sulfate.In vitrophosphorylation of brain phosphofructokinase had no affect on specific activity, inhibition by ATP, or activation by fructose 2,6-bisphosphate.