PMID: 23500663

Authors:

Loch JI, Bonarek P, Polit A, Ries D, Dziedzicka-Wasylewska M, Lewinski K

Title:

Binding of 18-carbon unsaturated fatty acids to bovine ss-lactoglobulin-Structural and thermodynamic studies.

Journal:

Int J Biol Macromol. 2013 Mar 15. pii: S0141-8130(13)00107-4. doi:, 10.1016/j.ijbiomac.2013.03.021.

Abstract:

Binding of 18-carbon unsaturated oleic and linoleic acid to lactoglobulin, the milk protein, has been studied for the first time by isothermal titration calorimetry (ITC) and X-ray crystallography. Crystal structures determined to resolution 2.10A have revealed presence of single fatty acid molecule bound in ss-barrel, the primary binding site, with carboxyl group hydrogen bonded to Glu62. The aliphatic chain of both ligands is in almost linear conformation and their interactions with the protein are similar to observed in structure of lactoglobulin with stearic acid. The ITC experiments showed that binding of unsaturated fatty acids to LGB is spontaneous and exothermic. The stoichiometry of binding is lower than 1.0, association constant is 9.7x105M-1 and 9.0x105M-1 for oleic and linoleic acid, respectively. Solvent relief seems to be the major contributor to entropic changes upon fatty acid binding to lactoglobulin.