Modelling steady state intercellular isotopic distributions with isotopomer decomposition units

In the past three decades, various computational frameworks for the modelling of the intracellular isotopic distribution have been proposed by different research groups. Among them the cascaded linear systems are the most popular approaches since they can transfer the nonlinear isotopomer labeling system into cascaded linear sub-systems. In this work, a novel two-step decomposition algorithm to model isotopomer labeling system is proposed. It can be utilized to decompose large metabolic networks. For convenience purpose, a new concept of isotopomer decomposition units (IDUs) is defined to distinguish the approach from others. Comparing to other cascaded linear systems, the IDU method follows a different decomposition procedure and results in another set of cascaded linear systems with different coefficients. Two variants of IDU algorithms are proposed, while one variant of them (IDU-B) has fewer number of balance equations than that of EMU balance equations. The efficiency of the IDU approach is demonstrated through two simulated examples.