CALCULATION OF TRANSFORMED THERMODYNAMIC PROPERTIES OF BIOCHEMICAL REACTANTS AT SPECIFIED PH AND PMG

The fundamental equation of thermodynamics for the transformed Gibbs energy G' at specified pH and pMg is used to derive the expressions for the standard transformed Gibbs energy of formation DELTA(f)G(i)'0 of a reactant, its standard transformed enthalpy of formation DELTA(f)H(i)'0, and its standard transformed entropy of formation DELTA(f)S(i)'0. The standard transformed Gibbs energy of reaction DELTA(r)G'0, standard transformed enthalpy of reaction DELTA(r)H'0, and standard transformed entropy of reaction DELTA(r)S'0 can be written as functions of pH and pMg in terms of the standard Gibbs energies of formation DELTA(f)G(i)0, standard enthalpies of formation DELTA(f)H(i)0, and standard entropies of formation DELTA(f)S(i)0 of the species involved. The expressions for DELTA(r)G'0, DELTA(r)H'0, and DELTA(r)S'0 can be rearranged to the usual forms involving a reference reaction. The standard transformed formation properties are calculated for glucose 6-phosphate (G6P) at 298.15 K, 1 bar. pH 7. pMg 3, and I = 0.25 M.