The Role of the Urea Cycle and Polyamines in Albumin Synthesis
The Role of the Urea Cycle and Polyamines in Albumin Synthesis
复制标题
尿素循环和多胺在白蛋白合成中的作用
作者：
M. Oratz;M. Rothschild;S. Schreiber;A. Burks;J. Mongelli;Barbara Matarese
白蛋白的合成受到那些增加尿素合成和膜结合多核糖体聚集的氨基酸的刺激。鸟氨酸是一种不掺入蛋白质中的氨基酸，由尿素循环中的精氨酸产生，是一种刺激白蛋白的氨基酸，是多胺的前体，我们已经证明多胺精胺促进结合的多核糖体聚集。为了测试尿素生成及其产生的鸟氨酸可能通过多胺途径在白蛋白合成调节中起关键作用的概念，用鸟氨酸、α-二氟甲基鸟氨酸（DFMO）和精胺灌注来自禁食供体的离体肝脏。在对照实验中，白蛋白合成为13.4 ± 0.8 mg/100 gm肝脏/hr，多核糖体聚集为47%。在存在鸟氨酸的情况下，这些增加（26.0 ± 2.6 mg和59%）;如果在添加鸟氨酸之前用DFMO预灌注肝脏，则不会发生白蛋白合成和多核糖体再聚集的预期增加（16.3 ± 1.4 mg和47%）。然而，如果在预灌注期间精胺与DFMO一起存在，则添加鸟氨酸具有预期效果（白蛋白合成= 26.1 ±1.2 mg，多核糖体聚集= 62%）。这表明，如果鸟氨酸至腐胺的途径被阻断，则鸟氨酸不刺激白蛋白合成，并为以下概念提供支持：（a）鸟氨酸刺激白蛋白产生是通过多胺合成，以及（B）尿素循环在蛋白质代谢中起着比简单的氮处置途径更重要的作用。
Albumin synthesis is stimulated by those amino acids which increase urea synthesis and membrane bound polysome aggregation. Ornithine, an amino acid not incorporated into protein and produced from arginine in the urea cycle, is an albumin‐stimulating amino acid and is the precursor of the polyamines, and we have shown that the polyamine spermine promotes bound polysome aggregation. To test the concept that ureogenesis with its generation of ornithine might play a key role in albumin synthesis regulation via the polyamine pathway, isolated livers from fasted donors were perfused with ornithine, α‐difluoromethyl ornithine (DFMO), and spermine. In control experiments, albumin synthesis was 13.4 ± 0.8 mg per 100 gm liver per hr and polysome aggregation was 47%. These were increased in the presence of ornithine (26.0 ± 2.6 mg and 59%); if the livers were preperfused with DFMO before the addition of ornithine, then the expected increase in albumin synthesis and polysome reaggregation did not occur (16.3 ± 1.4 mg and 47%). However, if spermine was present with DFMO during the preperfusion, then the addition of ornithine had the expected effect (albumin synthesis = 26.1 ±1.2 mg and polysome aggregation = 62%). This suggests that if the ornithine to putrescine pathway is blocked, ornithine does not stimulate albumin synthesis and offers support to the concepts that (a) ornithine stimulation of albumin production is via polyamine synthesis and (b) that the urea cycle plays a more important role in protein metabolism than simply the pathway for nitrogen disposal.
精胺对大鼠肝脏多聚核糖体和蛋白质合成的影响。
DOI：
10.1016/0006-2944(82)90009-6
发表时间：
1982
期刊：
Biochemical medicine
影响因子：
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作者：
Sidransky,H;Verney,E;Murty,CN
通讯作者：
Murty,CN