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Metabolite‐balancing techniques vs. 13 C tracer experiments to determine metabolic fluxes in hybridoma cells
Author(s) -
Bonarius Hendrik P. J.,
Timmerarends Bram,
de Gooijer Cornelis D.,
Tramper Johannes
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980420)58:2/3<258::aid-bit20>3.0.co;2-7
Subject(s) - metabolic flux analysis , tracer , flux (metallurgy) , metabolite , chemistry , metabolism , intracellular , nad+ kinase , biochemistry , enzyme , physics , organic chemistry , nuclear physics
The estimation of intracellular fluxes of mammalian cells using only mass balances of the relevant metabolites is not possible because the set of linear equations defined by these mass balances is underdetermined. In order to quantify fluxes in cyclic pathways the mass balance equations can be complemented with several constraints: (1) the mass balances of co‐metabolites, such as ATP or NAD(P)H, (2) linear objective functions, (3) flux data obtained by isotopic‐tracer experiments. Here, these three methods are compared for the analysis of fluxes in the primary metabolism of continuously cultured hybridoma cells. The significance of different theoretical constraints and different objective functions is discussed after comparing their resulting flux distributions to the fluxes determined using 13 CO 2 and 13 C‐lactate measurements of 1 − 13 C‐glucose‐fed hybridoma cells. Metabolic fluxes estimated using the objective functions “maximize ATP” and “maximize NADH” are relatively similar to the experimentally determined fluxes. This is consistent with the observation that cancer cells, such as hybridomas, are metabolically hyperactive, and produce ATP and NADH regardless of the need for these cofactors. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:258–262, 1998.