Zerez C R, Tanaka K R
Blood. 1987 Apr;69(4):999-1005.
Erythrocytes from individuals with pyruvate kinase (PK) deficiency have approximately half the total (oxidized and reduced) nicotinamide adenine dinucleotide (NAD) of normal erythrocytes. In order to elucidate the mechanism(s) for the decrease in total NAD, we examined NAD synthesis in intact erythrocytes. It is demonstrated that NAD synthesis is impaired in PK-deficient erythrocytes to a degree that is dependent on the PK activity and adenosine 5'-triphosphate (ATP) concentration of these cells. After incubation in the presence of fluoride, which simulates the characteristics of PK deficiency by inhibiting enolase, normal erythrocytes had impaired NAD synthesis and decreased ATP concentrations. Fluoride did not inhibit NAD synthesis in a hemolysate system that is not dependent on glycolysis for ATP generation. These data suggest that fluoride does not inhibit the enzymes of NAD synthesis and that impairment of NAD synthesis by fluoride is mediated by decreased ATP formation. Thus, it is concluded that impaired NAD synthesis in PK-deficient erythrocytes is caused by decreased ATP formation due to the PK deficiency. Since the rate of glycolysis is limited by the availability of NAD+, it is suggested that impaired NAD synthesis causes further ATP depletion and thereby may enhance hemolysis in PK-deficient erythrocytes.
患有丙酮酸激酶（PK）缺乏症的个体的红细胞中，总的（氧化型和还原型）烟酰胺腺嘌呤二核苷酸（NAD）含量约为正常红细胞的一半。为了阐明总NAD含量降低的机制，我们检测了完整红细胞中的NAD合成情况。结果表明，PK缺乏的红细胞中NAD合成受损，其受损程度取决于这些细胞的PK活性和腺苷5'-三磷酸（ATP）浓度。在氟化物存在的情况下孵育后，氟化物通过抑制烯醇化酶模拟PK缺乏的特征，正常红细胞的NAD合成受损且ATP浓度降低。氟化物在不依赖糖酵解产生ATP的溶血系统中不抑制NAD合成。这些数据表明，氟化物不抑制NAD合成酶，氟化物对NAD合成的损害是由ATP生成减少介导的。因此，可以得出结论，PK缺乏的红细胞中NAD合成受损是由于PK缺乏导致ATP生成减少所致。由于糖酵解速率受NAD+可用性的限制，提示NAD合成受损会导致进一步的ATP消耗，从而可能增强PK缺乏的红细胞中的溶血作用。
