Figure 5.

Metabolic cost of biosynthesis of amino acids and its relationship with physico-chemical properties of amino acids: correlations of metabolic cost (x axis) with (a) electrostatic potential energy (y axis on right) and experimentally measured cellular concentrations of amino acids (y axis on left), (b) with hydropathy index, (c) with volume in 3D space of the side chains, and (d) with side chain bond energy; the metabolic cost is represented in terms of number of ATP molecules required to synthesize one molecule of an amino acid.