State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Cytotechnology. 2006 May;51(1):21-8. doi: 10.1007/s10616-006-9010-y. Epub 2006 Aug 5.
To elucidate the metabolic characteristics of recombinant CHO cells expressing glutamine synthetase (GS) in the medium with or without glutamine, the concentrations of extra- and intracellular metabolites and the activities of key metabolic enzymes involved in glutamine metabolism pathway were determined. In the absence of glutamine, glutamate was utilized for glutamine synthesis, while the production of ammonia was greatly decreased. In addition, the expression of recombinant protein was increased by 18%. Interestingly, the intracellular glutamine maintained almost constant, independent of the presence of glutamine or not. Activities of glutamate-oxaloacetate aminotransferase (GOT), glutamate-pyruvate aminotransferase (GPT), and glutamate dehydrogenase (GDH) increased in the absence of glutamine. On the other hand, intracellular isocitrate and the activities of its downstream isocitrate dehydrogenase in the TCA cycle increased also. In combination with these two factors, a 8-fold increase in the intracellular alpha-ketoglutarate was observed in the culture of CHO-GS cells in the medium without glutamine.
为了阐明表达谷氨酰胺合成酶（GS）的重组 CHO 细胞在含有或不含有谷氨酰胺的培养基中的代谢特征，测定了细胞外和细胞内代谢物的浓度以及参与谷氨酰胺代谢途径的关键代谢酶的活性。在没有谷氨酰胺的情况下，谷氨酸被用于合成谷氨酰胺，而氨的生成量大大减少。此外，重组蛋白的表达增加了 18%。有趣的是，细胞内谷氨酰胺的含量几乎保持不变，与是否存在谷氨酰胺无关。在没有谷氨酰胺的情况下，谷氨酸-草酰乙酸转氨酶（GOT）、谷氨酸-丙酮酸转氨酶（GPT）和谷氨酸脱氢酶（GDH）的活性增加。另一方面，三羧酸循环中细胞内异柠檬酸及其下游异柠檬酸脱氢酶的活性也增加了。结合这两个因素，在没有谷氨酰胺的 CHO-GS 细胞培养基中，细胞内α-酮戊二酸增加了 8 倍。
