重组CHO细胞培养过程中氨对细胞代谢的影响

研究了重组CHO细胞批培养过程中，氨浓度对细胞的葡萄糖、谷氨酰胺及其它氨基酸代谢的影响。表明，细胞对葡萄糖和谷氨酰胺的得率系数随着氨浓度的增加而降低，起始氨浓度为566mmol/L的批培养过程与起始氨浓度为021mmol/L的批培养过程相比，细胞对葡萄糖和谷氨酰胺的得率系数分别下降了78%和74%，细胞对其它氨基酸的得率系数也分别下降了50%～70%。氨浓度的增加明显地改变了细胞的代谢途径，葡萄糖代谢更倾向于厌氧的乳酸生成。在谷氨酰胺的代谢过程中，谷氨酸经谷氨酸脱氢酶进一步生成α酮戊二酸的过程受到了氨的抑制，而氨对谷氨酸经谷氨酸转氨酶反应生成α酮戊二酸的过程有促进作用，但总体上谷氨酸进一步脱氨生成α酮戊二酸的反应受到了氨的限制。

Effects of Ammonia on Cell Metabolism in the Culture of Recombinant CHO Cells

The effects of ammonia on metabolism of glucose, glutamine and other amino acids in the batch culture of recombinant CHO cells were investigated. It was showed that the yields of cells to glucose, glutamine and other consumed amino acids decreased with the increase of initial ammonia concentrations. In the batch culture with initial ammonia concentration 5.66 mmol/L, the yields of cell to glucose and glutamine reduced 78% and 74%, respectively, compared to that with ammonia initial concentration 0.21 mmol/L, and the yields of cells to other consumed amino acids also reduced 50%-70%. The metabolic pathways were altered in the cultures with the higher ammonia concentrations. The glucose consumption was more prone to form lactate by anaerobic metabolism. In the glutamine metabolic process, the reaction of glutamate to alpha-ketoglutarate by the glutamate dehydrogenase was inhibited by ammonia, and that by the glutamate amino transferase was facilitated. However, the yields of glutamate to glutamine decreased with the increase of ammonia concentrations, showing that the reaction of glutamate to alpha-ketoglutarate was inhibited by ammonia as a whole.