Calculation of thermodynamic properties of protein in Escherichia coli K‐12 grown on succinic acid, energy changes accompanying protein anabolism, and energetic role of ATP in protein synthesis

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Abstract
Using an average of the results from three methods of calculation, estimations are made of the thermodynamic properties of a unit carbon formula weight (UCFW) of Escherichia coli K‐12 protein. These resulted in values fro ΔGf of −38.09 kJ (−9.10 kcal)/ UCFW, for ΔHf of −68.18 kJ (−16.29 kcal)/UCFW, and for ΔSf of −94.2 J (−22.5 cal)/UCFW deg. The absolute entropy of one UCFW of E. coli K‐12 protein is calculated to be 73.8 J/UCFW deg. Using these values, the corresponding changes in thermodynamic properties accompanying the anabolism of protein by this microorganism to from one UCFW of protein by this microorganism to from one UCFW of protein are calculated to be 1.97 kJ (0.47 kcal)/UCFW for ΔG, 0.75 kJ (0.18 kcal)/UCFW for ΔH, and −4.09 J (−0.98 cal)/UCFW deg for ΔS. All these values are sufficiently close to zero that they may be considered to be so. The question is raised as to the quantity of ATP energy conserved within the substance of the protein as it is synthesized from succinic acid. It is calculated that only 3.8% of the total free energy available from ATP that is required during protein anabolism can have been conserved within the substance of the protein, there being a net conversion of the remaninder into heat and entropy.