Arrhenius plots provide activation enthalpy
The negative enthalpy of activation for folding can arise
either from a breakdown of the two-state model or from
a positive entropy of activation. The latter is likely since
formation of the type-II b-turns involves a greater degree
of organization than that found in the unfolded state. The
time scale for folding in this study is representative of the
formation of b-turns as distinct from hydrophobic collapse
(3-5 ms time scale) or hydrogen bond formation (1 ns time
DHf‡ (kJ/mol) DHu‡ (kJ/mol)