a-La content in WPI-3. Upon heating, a-La will readily start to
unfold at relatively low temperature, however complete unfolding
of a-La requires more energy due to four intramolecular disulfide
bonds (Corredig & Dalgleish, 1996).
The a-La:b-Lg ratio appeared to be important for the observed
effects. Indeed, when the amount of a-La was reduced (WPI-2)
only a small change in enthalpy was observed (Fig. 1B). The secondary
structures of a-La and b-Lg differ to a great extent, as
a-La consists primarily of a-helices and b-Lg of b-sheets
(Uniprot, Universal Protein Resource database). This may provide
some evidence that the observed differences correlated to different
protein structure; b-sheet conformation is considered a more
stable structure than a-helices, which would explain why WPI-2