Dornand J, Bonnafous J C, Favero J, Gartner A, Mani J C
Biochim Biophys Acta. 1984 Aug 17;804(4):398-403. doi: 10.1016/0167-4889(84)90066-1.
It is now well established that human lymphoblastoid cell lines showing immaturity characters display ecto-5'-nucleotidase activities lower than normal levels. A recent paper (Sun, A.S., Holland, J.F. and Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577-584) mentioned that this phenomenon resulted from the presence of a 5'-nucleotidase inhibitor in these cell lines. We demonstrate here that the use of 5'-[3H]AMP as a substrate, and inadequate analysis of the products formed, led them to a misinterpretation. [3H]Adenosine derived from 5'-[3H]AMP hydrolysis was further transformed into [3H]inosine by the adenosine deaminase activity of the leukemic cell lines tested; [3H]inosine was precipitated with the excess substrate and was not taken into account in the ecto-5'-nucleotidase determination, which led the authors to confuse this adenosine deaminase activity with a 5'-nucleotidase inhibitor. We did not observe 5'-nucleotidase inhibition by leukemic cell cytosol when convenient assay methods were used and showed that the presence of such an inhibitor remains to be established.
现已充分证实，显示不成熟特征的人淋巴母细胞系表现出低于正常水平的ecto-5'-核苷酸酶活性。最近一篇论文（Sun, A.S., Holland, J.F. 和 Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577 - 584）提到，这种现象是由于这些细胞系中存在5'-核苷酸酶抑制剂所致。我们在此证明，使用5'-[³H]AMP作为底物，以及对所形成产物的分析不足，导致他们产生了误解。测试的白血病细胞系的腺苷脱氨酶活性将5'-[³H]AMP水解产生的[³H]腺苷进一步转化为[³H]肌苷；[³H]肌苷与过量底物一起沉淀，在ecto-5'-核苷酸酶测定中未被考虑，这导致作者将这种腺苷脱氨酶活性与5'-核苷酸酶抑制剂混淆。当使用合适的测定方法时，我们未观察到白血病细胞胞质溶胶对5'-核苷酸酶的抑制作用，并表明这种抑制剂的存在仍有待确定。
