表达rhTNFR-Fc的CHO细胞的氨基酸代谢特征及氨基酸流加培养工艺研究

Amino Acid Metabolism of CHO Cells Expressing rhTNFR-Fc and Amino Acid Supplement Strategies

为提高表达重组人肿瘤坏死因子受体-Fc融合蛋白(rhTNFR-Fc)的CHO工程细胞的培养密度和目的蛋白表达,研究了葡萄糖和谷氨酰胺流加-批式培养工艺的细胞氨基酸代谢特征及游离氨基酸和大豆蛋白水解物的补加策略。通过补加葡萄糖和谷氨酰胺浓缩液分别维持其浓度为10 mmol/L和2 mmol/L左右,在不同阶段定期补加特定的氨基酸浓缩液或大豆蛋白水解物补充氨基酸消耗,检测细胞培养上清中rhTNFR-Fc的表达。谷氨酸、天冬酰胺、天冬氨酸、脯氨酸等4种非必需氨基酸快速消耗,是CHO工程细胞增殖和目的蛋白表达的限制性底物。以游离氨基酸、游离氨基酸合并大豆蛋白水解物补充氨基酸消耗可分别使细胞生长密度提高50%、100%,目的蛋白表达增加60%、125%,培养时程延长44%、66%,同时葡萄糖比消耗率、乳酸比生成率降低,谷氨酰胺的利用效率提高。

In order to increase cell density of CHO cells expressing recombinant tumor necrosis factor receptor-Fc （rhTNFR-Fc） and protein productivity in glucose and glutamine fed-batch culture in spinning flasks, the addition strategy of amino acid and soy bean hydrolysate was investigated. The concentration of glucose and glutamine was maintained at 10 mmol/L and 2 mmol/L respectively by feeding their concentrations. The amino acids or soybean hydrolysate were periodically added to supply their consumption. rhTNFR-Fc in supernatant was analyzed by High performance affinity chromatography. It was found that four sorts of amino acids （ Glu, Asp, Asn and Pro ） were consumed rapidly,which were inhibitory substrates to cell growth and protein production. One amino acid（Ala） was produced and others were depleted slowly and remained half primary concentrations at the end of fed-batch culture. Cell density was increased by 50% and 100%, rhTNFR-Fc protein production was increased by 60% and 125 %, and culture length was increased by 44%. 66 % respectively by supplements of rapidly consumed amino acids with free amino acids alone, or combined with soy bean hydrolysate. In addition the glucose consumption rate and lactate production rate were reduced, and the glutamine utilization was more efficient. The optimization of amino acid supplement strategy offers an enormous potential for glucose and glutamine fed-batch culture.