Sadava D, Frykman P, Harris E, Majerus D, Mustard J, Bernard B
Keck Science Center, Claremont Colleges, Calif 91711.
Biol Neonate. 1992;62(2-3):89-95. doi: 10.1159/000243859.
The activities of two key enzymes of glycolysis and two key enzymes of gluconeogenesis were measured in liver samples from 44 human fetuses ranging in gestational age from 20 weeks to term, from infants to 10 years and from adults from 21 to 58 years. Specific activities of both gluconeogenic enzymes, fructose-1,6-biphosphatase and phosphoenolpyruvate carboxykinase, increased throughout the period of fetal development examined, and rose to near adult levels after birth. The activities of both glycolytic enzymes, phosphofructokinase 1 and pyruvate kinase, were lower in fetal than in pediatric and adult samples. For both of these enzymes, there was a significant reduction in activity of livers from fetuses of 34-37 weeks' gestation. Both enzymes showed hyperbolic kinetics at 24 weeks' gestation, but this changed to sigmoid kinetics during the 34-37 weeks' period of low activity. The data indicate that during the last weeks of gestation, inhibition of the activities of these two glycolytic enzymes, coupled with the rise in the two gluconeogenic enzymes, may reflect a change in liver from a primarily glycolytic role in the first two trimesters to a gluconeogenic role shortly before birth.
在44例人类胎儿、婴儿（10岁以下）及成人（21至58岁）的肝脏样本中，检测了糖酵解的两种关键酶及糖异生的两种关键酶的活性。所检测的整个胎儿发育阶段，两种糖异生酶，即果糖-1,6-二磷酸酶和磷酸烯醇式丙酮酸羧激酶的比活性均升高，并在出生后升至接近成人水平。两种糖酵解酶，即磷酸果糖激酶1和丙酮酸激酶，在胎儿样本中的活性低于儿童及成人样本。对于这两种酶，孕34 - 37周胎儿肝脏的酶活性显著降低。两种酶在孕24周时均呈现双曲线动力学，但在34 - 37周低活性期转变为S形动力学。数据表明，在妊娠的最后几周，这两种糖酵解酶活性的抑制，以及两种糖异生酶活性的升高，可能反映了肝脏在前两孕期主要发挥糖酵解作用，而在出生前不久转变为发挥糖异生作用。
