期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 68, 期 24, 页码 6701-6714出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jafc.0c00757
关键词
alpha-lactalbumin; UV irradiation; light-induced aggregation; disulfide; tryptophan; photo-oxidation
资金
- Innovation Fund Denmark [5158-00020B]
- China Scholarship Council
- CSC [201607940001]
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 alpha-lactalbumin (alpha-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by alpha-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 alpha-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in alpha-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 alpha-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met, and His residues.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据