[c] Mean residue ellipticity and estimated % Helicity as measured in 25 mM Tris, 150 mM NaCl, 5 mM MgCl2, pH 7.5 at 5 °C by CD spectroscopy and calculated using equations 6 and 7 (n = 2). 5 mol equivalents of TCEP were added to the samples to ensure that no oxidized species were present.