Ferenz C R, Nelson D A
Nucleic Acids Res. 1985 Mar 25;13(6):1977-95. doi: 10.1093/nar/13.6.1977.
The solubility of adult beta-globin chromatin (beta A chromatin) from immature chicken red blood cells can be controlled by the presence or absence of n-butyrate in a cell incubation medium. In the absence of n-butyrate, only a small percentage (approximately 4%) of the total beta A chromatin is in a soluble chromatin fraction following micrococcal nuclease digestion and centrifugation. This percentage increases to approximately 40-45% of the beta A chromatin if cells are incubated 1 hour in the presence of 10 mM sodium n-butyrate. The highest yield and enrichment of solubilized beta A chromatin is attained when 1-4% of the DNA is rendered acid soluble, and in buffers containing 1.5 - 5 mM MgCl2. The soluble beta A nucleohistone is nucleosome oligomer size (contains DNA 250-600 bases in length) and can be separated from soluble, transcriptionally inert mononucleosomes by agarose A-5m exclusion chromatography. The enhanced solubility appears to be specific for transcriptionally active chromatin. Whereas 40-45% of the beta A chromatin is recovered in the supernatant fraction from n-butyrate incubated immature erythrocytes, nucleohistone containing ovalbumin DNA sequences remains insoluble.
未成熟鸡红细胞中成人β-珠蛋白染色质（βA染色质）的溶解度可通过细胞培养液中是否存在正丁酸盐来控制。在没有正丁酸盐的情况下，经微球菌核酸酶消化和离心后，只有一小部分（约4%）的总βA染色质存在于可溶性染色质组分中。如果细胞在10 mM正丁酸钠存在的情况下孵育1小时，这个比例会增加到βA染色质的约40 - 45%。当1 - 4%的DNA变为酸溶性，且在含有1.5 - 5 mM MgCl2的缓冲液中时，可实现溶解的βA染色质的最高产量和富集。可溶性βA核组蛋白为核小体寡聚体大小（包含长度为250 - 600个碱基的DNA），可通过琼脂糖A - 5m排阻色谱法与可溶性、转录惰性的单核小体分离。增强的溶解度似乎对转录活性染色质具有特异性。虽然40 - 45%的βA染色质从经正丁酸盐处理的未成熟红细胞的上清液组分中回收，但含有卵清蛋白DNA序列的核组蛋白仍不溶解。
