SETTERFIELD G, DUNCAN R E
J Biophys Biochem Cytol. 1955 Sep 25;1(5):399-419. doi: 10.1083/jcb.1.5.399.
At a concentration of 9.6 x 10(-5)M, 2,6-diaminopurine (DAP) completely inhibited cell enlargement, cell division, and DNA synthesis (determined by microphotometric measurement of Feulgen dye) in Vicia faba roots. Inhibition of cell enlargement was partially reversed by adenine, guanine, xanthine, adenosine, and desoxyadenosine. Guanine and the nucleosides gave the greatest reversal, suggesting that one point of DAP action upon cell enlargement is a disruption of nucleoside or nucleotide metabolism, possibly during pentosenucleic acid synthesis. DAP inhibited cell division by preventing onset of prophase. At the concentrations used it had no significant effect on the rate or appearance of mitoses in progress. Inhibition of entrance into prophase was not directly due to inhibition of DNA synthesis since approximately half of the inhibited nuclei had the doubled (4C) amount of DNA. Adenine competitively reversed DAP inhibition of cell division, giving an inhibition index of about 0.5. Guanine gave a slight reversal while xanthine, hypoxanthine, adenosine, and desoxyadenosine were inactive. A basic need for free adenine for the onset of mitosis was suggested by this reversal pattern. Meristems treated with DAP contained almost no nuclei with intermediate amounts of DNA, indicating that DAP prevented the onset of DNA synthesis while allowing that underway to reach completion. The inhibition of DNA synthesis was reversed by adenine, adenosine, and desoxyadenosine although synthesis appeared to proceed at a slower rate in reversals than in controls. Inhibition of DNA synthesis by DAP is probably through nucleoside or nucleotide metabolism. A small general depression of DNA content of nuclei in the reversal treatments was observed. This deviation from DNA "constancy" cannot be adequately explained at present although it may be a result of direct incorporation of DAP into DNA. The possible purine precursor, 4-amino-5-imidazolecarboxamide gave no reversal of DAP inhibition of cell elongation and cell division and only a slight possible reversal of inhibition of DNA synthesis.
在浓度为9.6×10⁻⁵M时，2,6 - 二氨基嘌呤（DAP）完全抑制蚕豆根中的细胞增大、细胞分裂和DNA合成（通过对福尔根染料的显微光度测量来确定）。腺嘌呤、鸟嘌呤、黄嘌呤、腺苷和脱氧腺苷能部分逆转细胞增大的抑制作用。鸟嘌呤和核苷的逆转作用最大，这表明DAP对细胞增大作用的一个点是核苷或核苷酸代谢的破坏，可能发生在戊糖核酸合成过程中。DAP通过阻止前期的开始来抑制细胞分裂。在所使用的浓度下，它对正在进行的有丝分裂的速率或外观没有显著影响。进入前期的抑制并非直接由于DNA合成的抑制，因为大约一半被抑制的细胞核具有双倍（4C）的DNA量。腺嘌呤竞争性地逆转DAP对细胞分裂的抑制，抑制指数约为0.5。鸟嘌呤有轻微的逆转作用，而黄嘌呤、次黄嘌呤、腺苷和脱氧腺苷则无活性。这种逆转模式表明有丝分裂开始对游离腺嘌呤有基本需求。用DAP处理的分生组织几乎没有含中等量DNA的细胞核，这表明DAP阻止了DNA合成的开始，同时允许正在进行的合成完成。腺嘌呤、腺苷和脱氧腺苷能逆转DNA合成的抑制，尽管逆转时合成似乎比对照进行得更慢。DAP对DNA合成的抑制可能是通过核苷或核苷酸代谢。在逆转处理中观察到细胞核DNA含量有轻微的总体降低。目前尚不能充分解释这种与DNA“恒定性”的偏差，尽管这可能是DAP直接掺入DNA的结果。可能的嘌呤前体4 - 氨基 - 5 - 咪唑甲酰胺不能逆转DAP对细胞伸长和细胞分裂的抑制，对DNA合成抑制的逆转作用也很轻微。
