禁食和重新进食期间果糖1,6 - 二磷酸酶活性及分子特性的变化
Changes in activity and molecular properties of fructose 1, 6-bisphosphatase during fasting and refeeding.
作者信息
Pontremoli S, Melloni E, Salamino F, De Flora A, Horecker B L
出版信息
Proc Natl Acad Sci U S A. 1974 May;71(5):1776-9. doi: 10.1073/pnas.71.5.1776.
During prolonged starvation, fructose 1,6bisphosphatase (EC 3.1.3.11) activity in rabbit liver and kidney shows a transient decrease during the first 36 hr, before rising at 96 hr to levels severalfold higher than those found in the livers of fed animals. Proteolytic activity appears in the 105,000 x g supernatant fraction within several hours of starvation, and continues to increase during the entire 96-hr period. On refeeding, the activities return to nearly the control levels within 24 hr. The catalytic properties of fructose 1,6-bisphosphatase isolated from the livers of fasted rabbits are similar to those of the enzyme from fed animals, but its structure is modified, since it no longer contains the single tryptophan residue located near the NH(2)-terminus in the native enzyme. Thus this tryptophan residue is not required for the neutral pH optimum. The structural changes and the transient decrease in activity may be related to the observed increase in "free" proteolytic activity.
在长期饥饿期间，兔肝脏和肾脏中的果糖1,6 -二磷酸酶（EC 3.1.3.11）活性在最初36小时内出现短暂下降，然后在96小时时升至比喂食动物肝脏中发现的水平高出几倍的水平。饥饿后数小时内，蛋白水解活性出现在105,000×g上清液组分中，并在整个96小时期间持续增加。重新喂食后，这些活性在24小时内恢复到接近对照水平。从禁食兔肝脏中分离出的果糖1,6 -二磷酸酶的催化特性与喂食动物的酶相似，但其结构发生了改变，因为它不再含有天然酶中位于NH(2)-末端附近的单个色氨酸残基。因此，这个色氨酸残基对于中性pH最佳值不是必需的。结构变化和活性的短暂下降可能与观察到的“游离”蛋白水解活性增加有关。
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