Partially folded forms of barley lipid transfer protein are more surface active

Thermal and chemical modification of protein structures is known to affect their interfacial activity. We have looked in detail at the effect of heating on the structure and subsequently the surface properties of LTP1, a nonspecific lipid transfer protein from barley, both in the presence and in the absence of its lipid adduct. CD and NMR spectroscopy showed that some of the protein molecules refold back to the native state structure after being heated to 100 degrees C for 2 h. However, for a proportion of the molecules, the structure of the protein was irreversibly unfolded which resulted in an increase in surface activity irrespective of the presence of the lipid adduct. These molecules show an increase in surface activity, which is normally associated with an increase in molecular flexibility and surface hydrophobicity and is a property that has been shown to be highly sensitive to structural changes. This explains why thermal and chemical modification of LTP1 is important in optimizing the surface properties of the protein that are essential in diverse applications from biosensors to beer foam.