Calcium-Binding Protein Protocols Calcium-Binding Protein Protocols

130 Hicks et al.
Fig. 2. Debye plot for one of the data slices from the E-cadherin peak illustrating
the extrapolation of the scattering intensities to 0 angle. The calculated molecular
weight for this particular data slice was 24,367.
a physical constant, and θ is the measuring angle, is produced for each data slice
in the E-cadherin peak (see Fig. 2). In the Debye plot, the intercept of the
extrapolation of scattering intensities to 0 angle yields the molecular weight
directly. Once the molecular weight and concentration for each data slice has
been determined, the number, weight, and z average molecular weights can be
determined using the following equations:
Number Average: Mn = ∑ ci / ∑ (ci/Mi) Weight Average: Mw = ∑ (ci Mi) / ∑ ci z Average: Mz = ∑ (ci M 2
i ) / ∑ (ci Mi) Good agreement between the three calculated values indicates a fairly narrow,
monodisperse molecular weight distribution across the peak of interest, whereas
poor agreement indicates a more polydisperse distribution.
2.5. Notes
1. The flow cells in the Dawn F and Optilab 903 require utmost cleanliness for
reliable data collection. The Dawn F flow cell can be removed periodically and
disassembled for careful, manual cleaning, whereas the Optilab 903 flow cell