Reactivation kinetics of soman-inhibited human AChE mutants refractory to aging, by HI-6. Reactivation constants determined by nonlinear regression of data for human AChE mutants F338A (squares), E202Q/Y337A (black circles), F295L/F338A (triangles), and Y337A/F338A (white circles) in 0.1 m phosphate buffer, pH 7.4, at 22 °C are given in Table 3.