Investigation of the effect of oxidation on the structure of β-lactoglobulin by high resolution mass spectrometry

In this work, high-resolution mass spectrometry was used to identify the oxidation sites and forms of beta-lactoglobulin (beta-Lg) induced by hydrogen peroxide with 1.5% concentration, and the influence of oxidation sites on the structure of beta-Lg was discussed from the molecular level. Twelve kinds of oxidation products and 36 oxidation sites were identified, including sulfoxidation in sulfur-containing amino acid residue, hydroxylation in aromatic group residue, deamination in amino-containing amino acid etc. The destruction of hydrogen bonds and disulfide bonds in beta-Lg caused by oxidation is the main factor causing its structural changes, which were manifested in the decrease of beta-sheet component and increase of beta-turns and random coil contents, intrinsic fluorescence intensity and surface hydrophobicity. In addition, several peptides as potential oxidative markers were found to be capable of monitoring the degree of oxidation of beta-Lg. In short, this work provided insights into structural changes of beta-Lg by oxidation.

Automated summary

High-resolution mass spectrometry was used to identify the oxidation sites and forms of beta-lactoglobulin induced by hydrogen peroxide. The destruction of hydrogen bonds and disulfide bonds in beta-Lg caused by oxidation is the main factor causing its structural changes. This work provided insights into structural changes of beta-Lg by oxidation.