Eichner R D, Arnold R J
Biochem J. 1979 Nov 15;184(2):229-32. doi: 10.1042/bj1840229.
Bovine adipose-tissue glycogen metabolism was studied during food deprivation and re-feeding. Changes in the specific activity of adipose-tissue glycogen synthase paralleled changes in tissue glycogen content: both parameters increased during food deprivation and remained so during the first 10 days of re-feeding. The values for the A0.5 (activation constant) for glucose 6-phosphate of the freshly isolated enzyme from adipose tissue from fed and starved steers were 2.9 +/- 0.1 mM and 0.90 +/- 0.05 mM respectively. Additionally, whereas incubation of adipose-tissue extracts from fed steers did not activate endogenous glycogen synthase (through a presumed phosphoprotein phosphatase mechanism), the enzyme from starved or re-fed (up to 3 days re-feeding) steers was reversibly activated as measured by changes in the value for the A0.5 for glucose 6-phosphate. Thus activation of bovine adipose-tissue glycogen synthase during food deprivation appears to be related to expression of glycogen synthase phosphatase activity. These effects of food deprivation on bovine glycogen metabolism contrast markedly with the effects observed in rat adipose tissue.
对禁食和再喂食期间的牛脂肪组织糖原代谢进行了研究。脂肪组织糖原合酶的比活性变化与组织糖原含量变化平行：在禁食期间这两个参数均增加，并且在再喂食的前10天保持如此。来自喂食和饥饿阉牛的脂肪组织中新鲜分离酶的6-磷酸葡萄糖的A0.5（激活常数）值分别为2.9±0.1 mM和0.90±0.05 mM。此外，虽然来自喂食阉牛的脂肪组织提取物的孵育不会激活内源性糖原合酶（通过推测的磷蛋白磷酸酶机制），但通过6-磷酸葡萄糖的A0.5值变化测量，来自饥饿或再喂食（再喂食长达3天）阉牛的酶被可逆地激活。因此，禁食期间牛脂肪组织糖原合酶的激活似乎与糖原合酶磷酸酶活性的表达有关。禁食对牛糖原代谢的这些影响与在大鼠脂肪组织中观察到的影响明显不同。
