Glode L M, Kriegler M P, Livingston D M
Biochemistry. 1981 Mar 3;20(5):1306-11. doi: 10.1021/bi00508a041.
A series of human lymphoblastoid cell lines derived from nonleukemic donors are known to be cysteine prototrophs (cys+), while several lymphoblastoid lines derived from leukemic donors are cysteine auxotrophs (cys-). We have tested representative cell lines of each type for their content of cystathionase enzyme activity by a specific catalytic assay and their total cystathionase protein content by immunoprecipitation of in vivo labeled protein. There was a close correlation between the cellular content of the enzyme as determined in the two assays. Specifically, those cys+ lines having readily measureable enzyme by catalytic assay were found to contain significantly higher levels of immunoprecipitable Mr 43 000 cystathionase subunit than those cys- lines tested which were depleted in active enzyme. Thus, the absolute cysteine requirement of the leukemic, cys- cell lines tested is likely due to an intracellular reduction of cystathionase protein.
已知一系列源自非白血病供体的人类淋巴母细胞系是半胱氨酸原养型（cys+），而一些源自白血病供体的淋巴母细胞系是半胱氨酸营养缺陷型（cys-）。我们通过特定的催化测定法检测了每种类型的代表性细胞系中胱硫醚酶活性的含量，并通过体内标记蛋白的免疫沉淀法检测了它们的总胱硫醚酶蛋白含量。在两种测定法中确定的酶的细胞含量之间存在密切相关性。具体而言，通过催化测定法易于测量酶的那些cys+细胞系，被发现比所测试的活性酶缺乏的cys-细胞系含有显著更高水平的可免疫沉淀的43000 Mr胱硫醚酶亚基。因此，所测试的白血病cys-细胞系对半胱氨酸的绝对需求可能是由于胱硫醚酶蛋白的细胞内减少。
