Two of the samples mentioned above (CNGA1#621-690, CNGA3#626-694) were submitted to the Biophysics Resource of the W.M. Keck Biotechnology Facility at Yale University (New Haven, CT) for LS-SEC analysis. The samples were run on a Superdex 200 10/300 GL column (GE Healthcare) in 150 mM NaCl, 20 µM EDTA, 50 mM Tris-HCL, pH 8.0 (CNGA1#621-690) or 150 mM KCl, 30 mM HEPES, pH 7.5 (CNGA3#626-694). The molecular weight was determined by solving the equation that relates the excess scattered light, measured at several angles, to the concentration of solute and the weight-average molar mass using the ASTRA program 30 .