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Article The free energies of metabolic reactions (ΔG) are not positive
Author(s) -
Edwards Robert A.
Publication year - 2001
Publication title -
biochemistry and molecular biology education
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.34
H-Index - 39
eISSN - 1539-3429
pISSN - 1470-8175
DOI - 10.1111/j.1539-3429.2001.tb00085.x
Subject(s) - metabolic pathway , flux (metallurgy) , steady state (chemistry) , chemistry , energy metabolism , metabolic flux analysis , biophysics , biochemistry , metabolism , biology , organic chemistry , endocrinology
Biochemistry textbooks often erroneously state that some metabolic reactions have positive free energies (ΔG), which suggests that they are spontaneous in the reverse direction. This incorrectly implies that reverse fluxes can occur through some steps in a metabolic pathway while the overall flux through the pathway is in the forward direction. In fact, at steady state all the reactions of a metabolic pathway proceed in the forward direction with the same flux. During periods of transition between steady states a positive free energy for any one reaction in a pathway means that the pathway is not actually proceeding from beginning to end. © 2001 IUBMB. Published by Elsevier Science Ltd. All rights reserved.