Standard Gibbs Free Energy Changes of Enzyme Reactions in Metabolic Pathway Computation

Susumu Goto [1] (
Nobuhiro Fukushima [2] (
Minoru Kanehisa [1] (

[1] Institute for Chemical Research, Kyoto University
Gokasho, Uji, Kyoto 611, Japan
[2] Cray Research Japan LTD.
Nikko Ichibancho Bldg., 13-3 Ichiban-cho, Chiyoda-ku,
Tokyo 102, Japan


Standard Gibbs free energies of formation of biochemical compounds in aqueous solution are calculated and applied to determining the direction of enzyme reactions. Although we need more analysis, a large positive free energy change could be a barrier of an enzyme reaction and could be used to suppress biochemically infeasible reactions in the computed pathways. The values of free energy changes can also be used to select the most feasible candidate from several reactions that use the same substrate.