Butler M, Christie A
Department of Microbiology, University of Manitoba, Winnipeg, Canada.
Cytotechnology. 1994;15(1-3):87-94. doi: 10.1007/BF00762382.
Although glutamine is used as a major substrate for the growth of mammalian cells in culture, it suffers from some disadvantages. Glutamine is deaminated through storage or by cellular metabolism, leading to the formation of ammonia which can result in growth inhibition. Non-ammoniagenic alternatives to glutamine have been investigated in an attempt to develop strategies for obtaining improved cell yields for ammonia sensitive cell lines. Glutamate is a suitable substitute for glutamine in some culture systems. A period of adaptation to glutamate is required during which the activity of glutamine synthetase and the rate of transport of glutamate both increase. The cell yield increases when the ammonia accumulation is decreased following culture supplementation with glutamate rather than glutamine. However some cell lines fail to adapt to growth in glutamate and this may be due to a low efficiency transport system. The glutamine-based dipeptides, ala-gln and gly-gln can substitute for glutamine in cultures of antibody-secreting hybridomas. The accumulation of ammonia in these cultures is less and cell yields in dipeptide-based media may be improved compared to glutamine-based controls. In murine hybridomas, a higher concentration of gly-gln is required to obtain comparable cell growth to ala-gln or gln-based cultures. This is attributed to a requirement for dipeptide hydrolysis catalyzed by an enzyme with higher affinity for ala-gln than gly-gln.
尽管谷氨酰胺用作培养哺乳动物细胞生长的主要底物，但它存在一些缺点。谷氨酰胺在储存过程中或通过细胞代谢发生脱氨作用，导致氨的形成，这可能会抑制细胞生长。人们研究了谷氨酰胺的非产氨替代物，试图制定策略以提高对氨敏感细胞系的细胞产量。在某些培养系统中，谷氨酸是谷氨酰胺的合适替代品。需要一段适应谷氨酸的时间，在此期间谷氨酰胺合成酶的活性和谷氨酸的转运速率都会增加。在用谷氨酸而非谷氨酰胺补充培养后，当氨积累减少时，细胞产量会增加。然而，一些细胞系无法适应在谷氨酸中的生长，这可能是由于转运系统效率低下。基于谷氨酰胺的二肽，丙氨酰谷氨酰胺和甘氨酰谷氨酰胺可替代谷氨酰胺用于分泌抗体的杂交瘤培养。与基于谷氨酰胺的对照相比，这些培养物中氨的积累较少，基于二肽的培养基中的细胞产量可能会提高。在小鼠杂交瘤中，需要更高浓度的甘氨酰谷氨酰胺才能获得与丙氨酰谷氨酰胺或基于谷氨酰胺的培养物相当的细胞生长。这归因于对丙氨酰谷氨酰胺亲和力高于甘氨酰谷氨酰胺的酶催化二肽水解的需求。
