Effect of the air-water interface on the stability of beta-lactoglobulin.
We report the X-ray and neutron reflectometry measurements of the structural changes caused by chemical denaturation of a surface excess of the bovine milk protein, beta-lactoglobulin. The thickness of the diffuse protein surface layer was used as an order parameter as there was no corresponding increase in the surface excess as a function of guanidinium chloride (G.HCl) concentration. A thermodynamic analysis performed gave the interfacial free energy of unfolding in the absence of a denaturant (DeltaG(0)). This energy, lower than the free energy of unfolding bulk solution, shows that the air-water interface has a destabilizing effect on protein structure up to 50 kJ mol(-1).
Perriman
Adam W
AW
Research School of Chemistry, Australian National University, Canberra ACT 0200, Australia.
Henderson
Mark J
MJ
Holt
Stephen A
SA
White
John W
JW
D000388:Air; D004220:Disulfides / Q000737:chemistry; D007782:Lactoglobulins / Q000737:chemistry*; D011489:Protein Denaturation; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D004220:Disulfides; D007782:Lactoglobulins; D014867:Water