FIGURE 4.
Aggregation state of polycystin-2-(680–796). Plot of I/Iref as a function of the relative gradient strength G with I denoting the signal intensity at gradient G and Iref the intensity at the lowest gradient strength. The samples contained 200 μm polycystin-2-(680–796) in 5 mm Tris-HCl, pH 6.8, 500 mm NaCl, 0.1 mm DSS containing 90% H2O, and 10% D2O. As a reference DSS in buffer was used. Polyacrylamide (in 90% H2O, 10% D2O) was used to check the stability of the gradient system before and after the measurement. The signal of HDO in a sample of 99.9% D2O 0.1% H2O was used to calculate the diffusion constants D. *, polyacrylamide; +, HDO; ♢, DSS; ■, polycystin-2-(680–796) in the absence of divalent ions; ●, in the presence of 2 mm CaCl2; or ○, 2 mm MgCl2. Temperature was 298 K.