Effect of hydrostatic pressure on the spin state of P450-SS9 in solution at increasing concentrations of myristic acid (a) and arachidonoyl glycine (b). The plots shown on the left of each panel represent the content of the high-spin state as a function of pressure at various concentrations of substrates (0.5, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, and 70.0 μM of myristic acid and 4.0, 8.0, 16.0, 32.0, 70.0, and 280.0 μM arachidonoyl glycine for the panels A and B respectively). The plots shown on the right represent the same data set shown as the changes in the high spin content with increasing substrate concentration at a series of pressures increasing from 1 to 2000 bar in 200 bar increments. Solid lines show the results of fitting of the titration curves to the equation for the equilibrium of binary association.