Giannakouros T, Nikolakaki H, Georgatsos J G
Laboratory of Biochemistry, School of Chemistry, University of Thessaloniki, Greece.
Mol Cell Biochem. 1990 Dec 3;99(1):9-19. doi: 10.1007/BF01261388.
Spermidine and spermine at submillimolar concentrations stimulate the rate of incorporation of amino acid into protein in a cell-free system, directed either by endogenous or exogenous mRNA (TMV, globin). The stimulatory effects of these polyamines are exerted at both the stages of initiation and elogation and are more pronounced in the case of TMV or globin mRNA, amounting to approximately 2.3-fold stimulation over the polyamine-free system. The number of polysomes and the polysome-associated radioactivity increase approximately 2-fold in the presence of spermine. Synthesis of large polypeptides is a characteristic feature of the stimulatory event. However, elevated concentrations of spermidine and spermine strongly inhibit amino acid incorporation into protein. Inhibition is manifest at the stage of peptide elongation. In the case of endogenous mRNA the addition of an excess of polyamines results in a non uniform inhibition of amino acid incorporation. A most interesting finding is that, with increasing concentrations of polyamines, the intensity of four bands with Mr values of 63000, 44000, 15500 and 12500 respectively, increases or leastwise remains constant while others fade, indicating differential translation of proteins in the presence of polyamines.
亚毫摩尔浓度的亚精胺和精胺可刺激无细胞体系中氨基酸掺入蛋白质的速率，该体系由内源性或外源性信使核糖核酸（烟草花叶病毒、珠蛋白）指导。这些多胺的刺激作用在起始和延伸阶段均有体现，在烟草花叶病毒或珠蛋白信使核糖核酸的情况下更为明显，比无多胺体系的刺激作用约高2.3倍。在精胺存在的情况下，多核糖体的数量和与多核糖体相关的放射性增加约2倍。大分子量多肽的合成是刺激事件的一个特征。然而，高浓度的亚精胺和精胺会强烈抑制氨基酸掺入蛋白质。抑制作用在肽延伸阶段表现明显。在内源性信使核糖核酸的情况下，添加过量的多胺会导致氨基酸掺入的不均匀抑制。一个非常有趣的发现是，随着多胺浓度的增加，分子量分别为63000、44000、15500和12500的四条带的强度增加或至少保持不变，而其他条带则变淡，这表明在多胺存在的情况下蛋白质的翻译存在差异。
