Figure 3.

(A) Circular dichroism (CD) spectra of calsenilin EF3–4 in the absence (solid line) and presence (dashed line) of 10 μM Ca⁺² ions. The protein concentration used in these measurements was 10 μM. Increasing Ca⁺² concentrations resulted in similar CD spectra as the one obtained at 10 μM Ca⁺² ions. (B) DLS analysis of 15 mg/mL calsenilin EF3–4 in the presence vs. absence of 15 mM CaCl₂. The curves represent the relative mass-weighted molecular size distributions. The average hydrodynamic radii are 2.4 nm (with Ca²⁺) and 1.9 nm (Ca²⁺-free). A minor large aggregate component (50–100 nm) is also present. (C) Normalized A280 HPLC-SEC chromatograms of calsenilin EF3–4 at four injected concentrations: (a) 15 mg/mL; (b) 3 mg/mL; (c) 1 mg/mL; (d) 0.4 mg/mL. The monotonic shift of the SEC peaks to later elution times as a function of decreasing protein concentration is consistent with the decreasing absolute molecular weights determined by SLS measurements in each case (see Electronic supplemental Table).