Protein Concentration Dependence of Palmitate Binding to ß-Lactoglobulin

¹ Southeast Dairy Foods Research Center, Department of Food Science, North Carolina State University, Raleigh 27695-7624

The binding of palmitate to ß-lactoglobulin at protein concentrations ranging from 1 to 200 µM was determined using an ultrafiltration method with [¹⁴C]palmitate. Fit of the data to theoretical models required the assumption of two independent sets of binding sites; however, binding characteristics were dependent on the protein concentration. A model assuming one set of sites on the protein monomer and another on the dimer was consistent with the data. The analysis suggests that 2 mol of palmitate are bound/mol of dimer and that the binding constant is of the order of 10⁵ M^–1; a larger number of palmitate molecules are bound per mole of monomer with a smaller binding constant of the order of 10⁴ M^–1. Apparently, formation of the dimer, by hydrophobic interactions at the monomer contact site, eliminated palmitate binding sites on the monomer but formed a higher affinity pocket for binding to the dimer.

Key Words: ßbeta;-lactoglobulin • palmitate • palmitate binding

Submitted on April 18, 1997
Accepted on July 30, 1997

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