von der Decken A, Aström S, Arrhenius E K
J Nutr. 1981 Jul;111(7):1249-57. doi: 10.1093/jn/111.7.1249.
Protein restriction has been shown to produce either an enhancement or a reduction of transcription activity in vitro. Conditions for an enhanced transcription activity were investigated. Young male rats were fed a complete diet containing either 20% or 3% casein for 6 days. Body weight changed +7.4 g/day and -0.5 g/day, respectively. Liver wet weights were 6.8 and 3.7 g and the DNA amounts/g were 1.31 and 1.67 mg. Liver nuclei were incubated without or with 1 unit micrococcus nuclease (EC 3.1.4.7) per milligram of nuclear DNA, and chromatin was fractionated into a 2,000 x g, a 102,000 x g pellet and a supernatant fraction. In the livers of rats fed a low protein diet, chromatin-bound RNA polymerase I plus III and II activity/mg of fractional and nuclear DNA and soluble RNA polymerase activity were increased, while heparin-stimulated RNA polymerase II activity remained unchanged. An increased number of chains was synthesized by RNA polymerase I plus III without change in chain length and incorporation rate per chain. The length and incorporation rate per chain increased, while the number of chains synthesized by RNA polymerase II did not. After stimulation by heparin, an increased number of short chains was synthesized at a lower rate of incorporation per chain. In the complex chromating structures the capacity for RNA synthesis was determined by specific enzyme activity, RNA chain number and length.
蛋白质限制已被证明在体外可导致转录活性增强或降低。对增强转录活性的条件进行了研究。将年轻雄性大鼠分别喂食含20%或3%酪蛋白的完全饲料6天。体重变化分别为+7.4克/天和-0.5克/天。肝脏湿重分别为6.8克和3.7克，每克DNA含量分别为1.31毫克和1.67毫克。将肝细胞核在无或每毫克核DNA含1单位微球菌核酸酶（EC 3.1.4.7）的条件下孵育，然后将染色质分级分离为2000×g沉淀、102000×g沉淀和上清液部分。在喂食低蛋白饮食的大鼠肝脏中，与染色质结合的RNA聚合酶I加III以及II的活性/毫克分级和核DNA以及可溶性RNA聚合酶活性增加，而肝素刺激的RNA聚合酶II活性保持不变。RNA聚合酶I加III合成的链数增加，链长和每条链的掺入率不变。RNA聚合酶II合成的链长和每条链的掺入率增加，而合成的链数没有变化。经肝素刺激后，合成的短链数增加，但每条链的掺入率较低。在复杂的染色质结构中，RNA合成能力由特定酶活性、RNA链数和长度决定。
