Modification and oxidative degradation of β-lactoglobulin by UVB irradiation

Laura Fitzner; Toni Kühl; Mario Hasler; Diana Imhof; Karin Schwarz; Julia Katharina Keppler

doi:10.1016/j.foodchem.2023.136698

Modification and oxidative degradation of β-lactoglobulin by UVB irradiation

Food Chem. 2023 Dec 1:428:136698. doi: 10.1016/j.foodchem.2023.136698. Epub 2023 Jun 22.

Authors

Laura Fitzner¹, Toni Kühl², Mario Hasler³, Diana Imhof⁴, Karin Schwarz⁵, Julia Katharina Keppler⁶

Affiliations

¹ Institute of Human Nutrition and Food Science, Division Food Technology, Christian-Albrechts-University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany. Electronic address: [email protected].
² Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, Bonn 53121, Germany. Electronic address: [email protected].
³ Lehrfach Variationsstatistik, Christian-Albrechts-University of Kiel, Hermann-Rodewald-Strasse 9, 24118 Kiel, Germany. Electronic address: [email protected].
⁴ Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, Bonn 53121, Germany. Electronic address: [email protected].
⁵ Institute of Human Nutrition and Food Science, Division Food Technology, Christian-Albrechts-University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany. Electronic address: [email protected].
⁶ Laboratory of Food Process Engineering, Wageningen University & Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands. Electronic address: [email protected].

PMID: 37413838
DOI: 10.1016/j.foodchem.2023.136698

Abstract

Ultraviolet (UV) B irradiation induces protein modification, especially the conformational rearrangement of proteins, and is therefore promising as a non-thermal and non-chemical functionalization technique. Nevertheless, UVB irradiation introduces radicals and oxidizes side chains resulting in the loss of food quality. Thus, assessing the UVB irradiation-based functionalization of β-lactoglobulin (BLG) versus its oxidative degradation is of interest. UVB irradiation of up to 8 h was successfully applied to loosen the rigid folding of BLG and increase its flexibility. Thereby, the cysteine at position 121 and hydrophobic regions became surface-exposed as indicated by the increase in accessible thiol groups and increased surface hydrophobicity. Furthermore, we demonstrated the cleavage of the "outer" disulfide bond C⁶⁶-C¹⁶⁰ by LC-MS/MS after tryptic digestion of BLG. The 2-h-irradiated BLG showed adequate conformational rearrangement for protein functionalization while being minimally oxidized.

Keywords: Conformation; Disulfide cleavage; Functionalization; Oxidation; Ultraviolet irradiation; Whey protein.

MeSH terms

Chromatography, Liquid
Lactoglobulins* / chemistry
Oxidative Stress
Tandem Mass Spectrometry*
Ultraviolet Rays

Substances

Lactoglobulins