AMINO ACID METABOLISM IN MAMMALIAN CELL CULTURES
AMINO ACID METABOLISM IN MAMMALIAN CELL CULTURES
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DOI：
10.1126/science.130.3373.432
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发表时间：
1959-01-01
期刊：
影响因子：
56.9
通讯作者：
EAGLE, H
中科院分区：
文献类型：
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作者：
EAGLE, H
Harry Eagle 从含有鸟氨酸的培养基中提取瓜氨酸迄今为止尚未成功。可以考虑多种可能性来解释至少五个氮平衡不需要的氨基酸对于培养物中细胞的生存和生长是必需的这一事实。 1) 体内长时间生长过程中生物合成机制的丧失。在体外数百代的快速生长过程中，体内允许精氨酸、胞囊氨酸、谷氨酰胺、组氨酸和酪氨酸生物合成的酶系统可能已全部或部分丢失。为了评估这种可能性，在从动物宿主分离后 24 至 48 小时内以及广泛增殖之前，对源自猴肾、猴睾丸和兔胚胎组织的细胞在第一次培养传代中的氨基酸需求进行了检查 (11, 14)。长期细胞培养所需的所有 13 种氨基酸对于这些第一代细胞的存活和生长也是必需的。因此，需要 13 个氨基酸而不是 8 个氨基酸并不是由于在培养物中长时间生长过程中生物合成机制的丧失，但这些实验并不排除细胞在从动物体内移出后的最初 48 小时内失去必要的酶的可能性。 2）缺乏适当的前体或辅因子（亚叶酸在甘氨酸合成中的作用）。第二种可能性是培养的细胞保留了合成这五种氨基酸的能力，但由于缺乏适当的前体或辅因子，在培养物中并没有证明这一点。这种可能性在原代培养物中猴肾细胞的甘氨酸生物合成中得到了说明。为了获得最佳生长，这些细胞需要甘氨酸 (14, 15)，因为甘氨酸被部分阻断。丝氨酸转化为甘氨酸 (16)，并且已证明通过提供亚叶酸可以消除甘氨酸需求 (17)。这种细胞培养物对甘氨酸生物合成的主要阻碍显然是将叶酸还原为代谢活性辅因子。然而，尚未发现可被培养细胞用来代替预先形成的精氨酸、胞囊(e)氨酸、谷氨酰胺、组氨酸或酪氨酸的简单前体，并且尚未识别出可刺激培养细胞生物合成的辅助因子，如亚叶酸和甘氨酸。 3）生物合成能力有限，足以生存但不足以生长。
Harry Eagle citrulline from a medium containing ornithine have to date been unsuccessful. A number of possibilities may be con-sidered in explanation of the fact that at least five amino acids which are not required for nitrogen balance are never-theless essential for thesurvival and growth of cells in culture. 1) Loss of biosynthetic mechanisms during prolonged growthin vivo. The enzymatic systems which, in vivo, permit the biosynthesis of arginine, cyst (e) ine, glutamine, histidine, and tyrosine may have been lost, in whole or in part, dur-ing the hundreds ofgenerations of rapid growth in vitro. To assess this possibility, cells deriving from monkey kidney, mon-key testis, and rabbit embryonictissues were examined with respect to their amino acid requirements in first culture passage, within 24 to 48 hours after their isolation from the animal host and prior to extensive multiplication (11, 14). All 13 amino acids required by long-term cell cultures were necessary also for the survival and growth of these first-passage cells. The requirement for 13 amino acids rather than eight is therefore not due to loss of biosynthetic mechanisms in the course of prolonged growth in culture, but these experiments do not exclude the possibility that the necessary enzymes are lost from the cells within the first 48 hours after their re-moval from the animal. 2) Lack of appropriate precursors or cofactors (therole of folinic acid in gly-cine synthesis). A second possibility is that cultured cells retain the capacity to synthesize these five amino acids but that this is not evidenced in culture for lack of appropriate precursors or cofac-tors. This possibility is illustrated in the biosynthesis of glycine by monkey kidney cells in primary culture. For optimum growth, these cells require glycine (14, 15) because of a partial blockin the. con-version of serine to glycine (16), and that glycine requirement has been shown to be eliminated by the provision of folinic acid (17). The primary block in the biosynthesis of glycine by this cell culture is apparently in the reduction of folic acid to the metabolically active cofactor. However, no simple precursor has yet been found which can be used by cultured cells in lieu of preformed arginine, cyst (e) ine, glutamine, histidine, or tyro-sine, and no cofactor has been recog-nized which, as in the case of folinic acid and glycine, will stimulate that biosynthesis by cultured cells. 3) Limited biosynthetic capacity, suffcient for survival but not for growth.