Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure

Research output: Contribution to journalJournal articleResearchpeer-review

Standard

Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure. / Zhao, Zichen; Engholm-Keller, Kasper; Poojary, Mahesha M.; Boelt, Sanne G.; Rogowska-Wrzesinska, Adelina; Skibsted, Leif H.; Davies, Michael J.; Lund, Marianne N.

In: Journal of Agricultural and Food Chemistry, Vol. 68, No. 24, 2020, p. 6701-6714.

Research output: Contribution to journalJournal articleResearchpeer-review

Harvard

Zhao, Z, Engholm-Keller, K, Poojary, MM, Boelt, SG, Rogowska-Wrzesinska, A, Skibsted, LH, Davies, MJ & Lund, MN 2020, 'Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure', Journal of Agricultural and Food Chemistry, vol. 68, no. 24, pp. 6701-6714. https://doi.org/10.1021/acs.jafc.0c00757

APA

Zhao, Z., Engholm-Keller, K., Poojary, M. M., Boelt, S. G., Rogowska-Wrzesinska, A., Skibsted, L. H., ... Lund, M. N. (2020). Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure. Journal of Agricultural and Food Chemistry, 68(24), 6701-6714. https://doi.org/10.1021/acs.jafc.0c00757

Vancouver

Zhao Z, Engholm-Keller K, Poojary MM, Boelt SG, Rogowska-Wrzesinska A, Skibsted LH et al. Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure. Journal of Agricultural and Food Chemistry. 2020;68(24):6701-6714. https://doi.org/10.1021/acs.jafc.0c00757

Author

Zhao, Zichen ; Engholm-Keller, Kasper ; Poojary, Mahesha M. ; Boelt, Sanne G. ; Rogowska-Wrzesinska, Adelina ; Skibsted, Leif H. ; Davies, Michael J. ; Lund, Marianne N. / Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure. In: Journal of Agricultural and Food Chemistry. 2020 ; Vol. 68, No. 24. pp. 6701-6714.

Bibtex

@article{e26830bd5d3d4eda9edbd704c09a400f,
title = "Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure",
abstract = "Whey proteins are widely used as ingredients in the form of aggregates to obtain certain functionalities in food applications. The aim of this study was to understand how UV illumination generates aggregates of α-lactalbumin (α-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by α-LA caused cleavage of disulfide bonds and release of thiol groups, which resulted in primarily disulfide-mediated aggregation. This process mediated efficient aggregation with up to 98{\%} monomer conversion into aggregates through formation of intermolecular disulfide bonds, while only minor levels of nonreducible cross-links were observed. SDS-PAGE analysis revealed that illumination led to formation of dimeric, trimeric, and oligomeric forms of α-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in α-LA were cleaved by UV illumination but to different extents, and the extent of cleavage was found to be higher in the absence of calcium. Seventeen different non-native disulfides were formed after 24 h of UV illumination. Two dityrosine bonds were identified (Tyr103-Tyr103 and Tyr36-Tyr103) alongside ditryptophan (Trp118-Trp118) and tyrosine-tryptophan (Tyr50-Trp60) cross-links. In addition, Trp60, Trp118, Cys73, Cys91, Cys120, Phe80, Met90, His68, and His107 were found to be oxidized up to 12{\%} as compared to a nonilluminated control. Our work illustrates that light exposure can be used for generation of α-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met, and His residues.",
keywords = "disulfide, light-induced aggregation, photo-oxidation, tryptophan, UV irradiation, α-lactalbumin",
author = "Zichen Zhao and Kasper Engholm-Keller and Poojary, {Mahesha M.} and Boelt, {Sanne G.} and Adelina Rogowska-Wrzesinska and Skibsted, {Leif H.} and Davies, {Michael J.} and Lund, {Marianne N.}",
year = "2020",
doi = "10.1021/acs.jafc.0c00757",
language = "English",
volume = "68",
pages = "6701--6714",
journal = "Journal of Agricultural and Food Chemistry",
issn = "0021-8561",
publisher = "American Chemical Society",
number = "24",

}

RIS

TY - JOUR

T1 - Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure

AU - Zhao, Zichen

AU - Engholm-Keller, Kasper

AU - Poojary, Mahesha M.

AU - Boelt, Sanne G.

AU - Rogowska-Wrzesinska, Adelina

AU - Skibsted, Leif H.

AU - Davies, Michael J.

AU - Lund, Marianne N.

PY - 2020

Y1 - 2020

N2 - Whey proteins are widely used as ingredients in the form of aggregates to obtain certain functionalities in food applications. The aim of this study was to understand how UV illumination generates aggregates of α-lactalbumin (α-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by α-LA caused cleavage of disulfide bonds and release of thiol groups, which resulted in primarily disulfide-mediated aggregation. This process mediated efficient aggregation with up to 98% monomer conversion into aggregates through formation of intermolecular disulfide bonds, while only minor levels of nonreducible cross-links were observed. SDS-PAGE analysis revealed that illumination led to formation of dimeric, trimeric, and oligomeric forms of α-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in α-LA were cleaved by UV illumination but to different extents, and the extent of cleavage was found to be higher in the absence of calcium. Seventeen different non-native disulfides were formed after 24 h of UV illumination. Two dityrosine bonds were identified (Tyr103-Tyr103 and Tyr36-Tyr103) alongside ditryptophan (Trp118-Trp118) and tyrosine-tryptophan (Tyr50-Trp60) cross-links. In addition, Trp60, Trp118, Cys73, Cys91, Cys120, Phe80, Met90, His68, and His107 were found to be oxidized up to 12% as compared to a nonilluminated control. Our work illustrates that light exposure can be used for generation of α-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met, and His residues.

AB - Whey proteins are widely used as ingredients in the form of aggregates to obtain certain functionalities in food applications. The aim of this study was to understand how UV illumination generates aggregates of α-lactalbumin (α-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by α-LA caused cleavage of disulfide bonds and release of thiol groups, which resulted in primarily disulfide-mediated aggregation. This process mediated efficient aggregation with up to 98% monomer conversion into aggregates through formation of intermolecular disulfide bonds, while only minor levels of nonreducible cross-links were observed. SDS-PAGE analysis revealed that illumination led to formation of dimeric, trimeric, and oligomeric forms of α-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in α-LA were cleaved by UV illumination but to different extents, and the extent of cleavage was found to be higher in the absence of calcium. Seventeen different non-native disulfides were formed after 24 h of UV illumination. Two dityrosine bonds were identified (Tyr103-Tyr103 and Tyr36-Tyr103) alongside ditryptophan (Trp118-Trp118) and tyrosine-tryptophan (Tyr50-Trp60) cross-links. In addition, Trp60, Trp118, Cys73, Cys91, Cys120, Phe80, Met90, His68, and His107 were found to be oxidized up to 12% as compared to a nonilluminated control. Our work illustrates that light exposure can be used for generation of α-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met, and His residues.

KW - disulfide

KW - light-induced aggregation

KW - photo-oxidation

KW - tryptophan

KW - UV irradiation

KW - α-lactalbumin

U2 - 10.1021/acs.jafc.0c00757

DO - 10.1021/acs.jafc.0c00757

M3 - Journal article

C2 - 32396720

AN - SCOPUS:85086681631

VL - 68

SP - 6701

EP - 6714

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

SN - 0021-8561

IS - 24

ER -

ID: 244279904