The binding mechanism of lecithin to soybean 11S and 7S globulins using fluorescence spectroscopy

Interactions between lecithin (Lec) and soybean 11S and 7S globulins were investigated using fluorescence spectroscopy. Fluorescence of 11S and 7S was quenched by Lec. The quenching mechanism was static due to formation of a complex. Thermodynamic parameters were measured using the van't Hoff equation. Interactions of Lec with both globulins were driven by hydrophobic forces and binding processes were spontaneous. A larger absolute value of Delta G for 11S indicated that binding of 11S was much easier with Lec. Three-dimensional fluorescence spectra showed that binding of Lec with 11S more easily induced changes in the microenvironments of Trp and Tyr and in the polypeptide backbone structure of 11S. Simulated experiments verified that soybean proteins with a high 11S content combine both more easily and more strongly with Lec.