Figure 7: Proposed mechanism for NT dimerization.
(a) NT molecules with a monomer conformation where W10 is buried in the hydrophobic core. (b) Electrostatic interactions mediated by D40, K65 R60 and possibly E84 in their charged state lead to elevated pKa values for E79 and E119 due to a changed environment between associated monomer subunits. (c) Protonation of E79 and E119 at pH 6.5 leads to the structural conversion to a weakly associated dimer conformation in which W10 becomes exposed to a more polar environment. (d) Upon further decrease in pH to 5.7, protonation of E84 promotes conversion from weakly associated dimers to strongly associated and fully stable dimers.
