Miller D M, Williams R, McCarty K S
Department of Biochemistry, Duke University, Medical Center, Durham, NC 27710, USA.
Biochim Biophys Acta. 1973 Aug 30;317(2):437-46. doi: 10.1016/0005-2795(73)90236-5.
Histones of isolated calf thymus chromatin incubated in the presence of [14C]acetyl-CoA are radioactively acetylated, at specific residues. Incubation of calf thymus chromatin with [14C]acetate, however, gives no radioactive acetylation. The distribution of the radioactivity among the histone fractions corresponds well to that observed after incubation of calf thymus nuclei with [14C]acetate. The most striking observation is the complete absence of acetylation of histone F1 in both experiments. The specific activity of histones acetylated in vitro is much greater than that of histones acetylated in calf thymus nuclei, most likely reflecting a smaller degree of dilution of the labelled acetate donor. Investigation of the specificity of acetylation of each histone fraction reveals that for each histone fraction, specific peptides are acetylated in vitro which correspond to the histone peptides acetylated in calf thymus nuclei. Histones F2a1 and F2a2, however, also demonstrate additional minor sites of acetylation in the in vitro studies.
在[14C]乙酰辅酶A存在的情况下孵育的分离小牛胸腺染色质的组蛋白会在特定残基处发生放射性乙酰化。然而，用[14C]乙酸盐孵育小牛胸腺染色质却不会产生放射性乙酰化。放射性在组蛋白组分中的分布与用[14C]乙酸盐孵育小牛胸腺细胞核后观察到的情况非常吻合。最显著的观察结果是在两个实验中组蛋白F1都完全没有乙酰化。体外乙酰化组蛋白的比活性远高于小牛胸腺细胞核中乙酰化组蛋白的比活性，这很可能反映出标记的乙酸盐供体的稀释程度较小。对每个组蛋白组分乙酰化特异性的研究表明，对于每个组蛋白组分，体外都有特定的肽段被乙酰化，这些肽段与小牛胸腺细胞核中被乙酰化的组蛋白肽段相对应。然而，在体外研究中，组蛋白F2a1和F2a2也显示出额外的次要乙酰化位点。
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