Shin-Buehring Y S, Beier T, Tan A, Osang M, Schaub J
Pediatr Res. 1977 Oct;11(10 Pt 1):1045-51. doi: 10.1203/00006450-197710000-00004.
The activity of galactose-1-phosphate uridyltransferase (transferase) and galactokinase in several organs from human fetuses 7-28 weeks old was measured by using radioactive substrates and column chromatography for product identification. The specific activity of transferase and galactokinase increased with gestational age and reached, at the 28th week, a maximal level of 30.0 and 7.9 nmol/min/mg protein (units) in liver, 4.7 and 2.5 units in kidney, 6.0 and 4.0 units in lung, 6.7 and 2.9 units in spleen, 5.2 and 2.6 units in cardiac muscle, and 4.0 and 1.4 units in skeletal muscle, respectively. The activity in brain, on the other hand, remained quite constant with 1.2 units in the case of transferase and 0.5 units in the case of galactokinase during this period. The activities of both enzymes in the liver of children were slightly lower than the highest fetal level during the period of pregnancy studied. Galactokinase activity in fetal erythrocytes was approximately 4 times higher and the transferase activity approximately 30% higher than in adults. The Km value of fetal liver transferase for galactose-1-phosphate was found to be 0.330-0.357 mM and that of galactokinase for galactose, 0.265-0.277 mM.
采用放射性底物和柱色谱法进行产物鉴定，测定了7至28周龄人类胎儿多个器官中1-磷酸半乳糖尿苷转移酶（转移酶）和半乳糖激酶的活性。转移酶和半乳糖激酶的比活性随胎龄增加而升高，在第28周时，肝脏中分别达到最高水平30.0和7.9 nmol/分钟/毫克蛋白（单位），肾脏中为4.7和2.5单位，肺中为6.0和4.0单位，脾脏中为6.7和2.9单位，心肌中为5.2和2.6单位，骨骼肌中为4.0和1.4单位。另一方面，在此期间，脑中转移酶的活性为1.2单位，半乳糖激酶的活性为0.5单位，保持相当稳定。在所研究的孕期中，儿童肝脏中这两种酶的活性略低于胎儿最高水平。胎儿红细胞中的半乳糖激酶活性约为成人的4倍，转移酶活性约比成人高30%。发现胎儿肝脏转移酶对1-磷酸半乳糖的Km值为0.330 - 0.357 mM，半乳糖激酶对半乳糖的Km值为0.265 - 0.277 mM。
