Rogers S R, Bovee B W, Saunders S L, Segal S
Division of Biochemical Development and Molecular Diseases, Children's Hospital of Philadelphia, Pennsylvania 19104.
Pediatr Res. 1989 Feb;25(2):161-6. doi: 10.1203/00006450-198902000-00017.
The sp act of hepatic galactose-metabolizing enzymes, galactokinase, galactose-1-phosphate uridyltransferase, and uridine diphosphate-4-epimerase were measured in female rats during pregnancy and lactation as well as in fetuses and pups after parturition. Sp act for transferase and epimerase in pregnant rat liver are about 50% higher than that of virgin females, and with the increase in organ size during pregnancy the total hepatic activity is double that of nonpregnant animals. Galactokinase activity decreases somewhat during pregnancy, but total activity is 25% higher than in virgin liver. A Michaelis-Menten kinetic analysis of liver transferase indicates an increase in the maximum velocity of the reaction without a change in Km. Isoelectricfocusing on a high-resolution IEF gel demonstrated similar isozyme patterns. The sp act of the fetal liver enzymes increase to about twice that of the maternal tissue, but total activities are low due to the very small fetal liver size. Sp act of these enzymes in maternal liver fall after delivery, but sp act of galactokinase and transferase are programmed to increase in liver of the growing neonatal animals, reaching levels almost 5-fold higher than found in nonpregnant adult liver. An understanding of factors contributing to the enhanced transferase activity of the liver of pregnant and neonatal rats may contribute to possible ways of augmenting the residual transferase activity of patients with transferase-deficient galactosemia as a therapeutic strategy.
在雌性大鼠的怀孕期和哺乳期以及分娩后的胎儿和幼崽中，测定了肝脏中半乳糖代谢酶（半乳糖激酶、1-磷酸半乳糖尿苷转移酶和尿苷二磷酸-4-表异构酶）的比活性。怀孕大鼠肝脏中转移酶和表异构酶的比活性比未生育的雌性大鼠高约50%，并且随着孕期器官大小的增加，肝脏总活性是未怀孕动物的两倍。半乳糖激酶活性在孕期有所下降，但总活性比未生育肝脏高25%。对肝脏转移酶进行的米氏动力学分析表明，反应的最大速度增加而米氏常数不变。在高分辨率IEF凝胶上进行的等电聚焦显示了相似的同工酶模式。胎儿肝脏酶的比活性增加到母体组织的约两倍，但由于胎儿肝脏非常小，总活性较低。这些酶在母体肝脏中的比活性在分娩后下降，但半乳糖激酶和转移酶的比活性在新生动物生长过程中会在肝脏中程序性增加，达到比未怀孕成年肝脏中发现的水平高近5倍。了解导致怀孕和新生大鼠肝脏转移酶活性增强的因素，可能有助于找到增强转移酶缺乏型半乳糖血症患者残余转移酶活性的治疗策略。
