Figure 4

Sedimentation equilibrium analysis of the Grb7 SH2 and Grb7. (a) Absorbance at 280 nm verses radius data at sedimentation equilibrium for Grb7 SH2 at an initial loading concentration of 36 μM. The data collected at 14,000 rpm (circles), 16,600 rpm (squares), 24,300 rpm (diamonds) and 28,800 rpm (triangles) were fitted simultaneously using the nonlinear regression program [48]. (b) Absorbance at 280 nm verses radius data at sedimentation equilibrium for Grb7 at an initial loading concentrations of 12 μM. The data collected at 10,000 rpm (circles) and 11,800 rpm (squares) were fitted simultaneously using the nonlinear regression program NONLIN [77]. The solid line represents the calculated fit to a monomer-dimer model. The residuals of the fit are shown in the upper panels. Samples were in 50 mM MES pH 6.6, 100 mM NaCl and 1 mM DTT. The experiments were conducted at 20°C.