Goldstein D E, Curnow R T
Diabetes. 1980 Mar;29(3):217-20. doi: 10.2337/diab.29.3.217.
The effects of diabetes mellitus on glycogen synthase and its activating system (synthase phosphatase) were studied using human polymorphonuclear leukocytes (PMN). PMN were obtained from control subjects and diabetic patients by a gradient sedimentation technique. Enzyme activities of endogenous synthase-l and total synthase were not statistically different in diabetic and control cells. For measurement of endogenous synthase phosphatase, cells were sonicated in 50 mM Tris buffer (pH 7.5) and incubated at 30 degrees C. Conversion of synthase-D to -l and the maximum percent synthase-l attained were decreased in homogenates of diabetic cells. There was no correlation between the plasma glucose concentration and the rate of conversion of synthase-D to -l. Synthase phosphatase activities were also measured using a purified synthase-D substrate. Under these experimental conditions, glycogen synthase phosphatase activities did not differ in control and diabetic cells. These results are consistent with a diabetes-induced defect in conversion of endogenous synthase-D to -l at the level of the synthase enzyme rather than at that of the activating phosphatase.
利用人多形核白细胞（PMN）研究了糖尿病对糖原合酶及其激活系统（合酶磷酸酶）的影响。通过梯度沉降技术从对照受试者和糖尿病患者获取PMN。糖尿病细胞和对照细胞中内源性合酶-1和总合酶的酶活性无统计学差异。为测定内源性合酶磷酸酶，将细胞在50 mM Tris缓冲液（pH 7.5）中超声处理，并在30℃孵育。糖尿病细胞匀浆中合酶-D向-l的转化以及达到的合酶-1最大百分比均降低。血浆葡萄糖浓度与合酶-D向-l的转化率之间无相关性。还使用纯化的合酶-D底物测量合酶磷酸酶活性。在这些实验条件下，对照细胞和糖尿病细胞中的糖原合酶磷酸酶活性无差异。这些结果与糖尿病诱导的内源性合酶-D在合酶水平而非激活磷酸酶水平向-l转化的缺陷一致。
