Franzke R, Jelkmann W
Pflugers Arch. 1982 Jul;394(1):21-5. doi: 10.1007/BF01108303.
The low 2,3-disphosphoglycerate (2,3-DPG) level of fetal rabbit red cells has been attributed previously to a very high pyruvate kinase (PK) activity. The present report shows that the high PK activity is associated with a distinct fetal isozyme. Fetal and adult rabbit red cell PK were characterized by the methods recommended by the International Committee for Standardization in Haematology. Fetal red cell PK differed from the adult enzyme by its greater thermostability, lower affinities for phosphoenolpyruvate and ADP, higher nucleotide specificity and lower ATP inhibition. Marked electrophoretic differences were not detected. Our results indicate that there is a developmental change in red cell PK isozyme expression in the rabbit. We do not know, however, if this change arises at the gene level or from cell-age dependent postsynthetic modifications of the enzyme. But in view of the role of PK in the control of the 2,3-DPG level and thereby of the oxygen affinity of red blood cells, we assume that the physiological significance of the PK isozyme change is akin to that of the switch from fetal to adult hemoglobin in other species.
胎兔红细胞中2,3 -二磷酸甘油酸（2,3-DPG）水平较低，此前一直被认为是由于丙酮酸激酶（PK）活性非常高所致。本报告表明，高PK活性与一种独特的胎儿同工酶有关。采用国际血液学标准化委员会推荐的方法对胎兔和成年兔红细胞PK进行了表征。胎兔红细胞PK与成年酶的不同之处在于其热稳定性更高、对磷酸烯醇丙酮酸和ADP的亲和力更低、核苷酸特异性更高以及ATP抑制作用更低。未检测到明显的电泳差异。我们的结果表明，兔红细胞PK同工酶表达存在发育变化。然而，我们不知道这种变化是发生在基因水平，还是源于酶的细胞年龄依赖性合成后修饰。但鉴于PK在控制2,3-DPG水平以及由此控制红细胞氧亲和力方面的作用，我们认为PK同工酶变化的生理意义与其他物种从胎儿血红蛋白向成人血红蛋白的转变类似。
