Secondary structural analysis of TM4-tethered Cx26CT nonsyndromic recessive hearing loss mutants. CD spectra of TM4-Cx26CT mutants (A) L214P and (B) K224Q alone and in the presence of 0%, 5%, 10%, 15%, and 30% TFE, MES buffer, 8% LPPG, and at pH 7.5 and pH 5.8. (C) CD Spectra of the Cx26 TM4 WT and L214P at pH 7.5 and 5.8.