FOOD SCIENCE ›› 2021, Vol. 42 ›› Issue (2): 1-7.doi: 10.7506/spkx1002-6630-20200116-198

• Food Chemistry •     Next Articles

Preparation and Antigenicity of Site-specific PEGylated Beta-lactoglobulin

LIU Chengmei, JIANG Xinlin, LI Dongmei, ZHOU Lei, ZHONG Junzhen, JI Li, LUO Shunjing   

  1. (1. State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China;2. Jiangxi Danxia Biotechnology Co. Ltd., Yingtan 335200, China)
  • Online:2021-01-18 Published:2021-01-27

Abstract: In order to investigate the effect of different covalent modification sites on the antigenicity of β-lactoglobulin (β-LG), β-LG was modified by using cysteine-specific PEGylation at the thiol group of Cys121. Using one-factor-at-a-time method, the optimal modification conditions were determined as follows: β-LG and mPEG-MAL (molar ratio, 1:30) were dissolved together in 0.1 mol/L phosphate buffer containing 0.3 mol/L tris-(2-carboxyethyl) phosphine (TCEP), 25% (V/V) ethanol and 2 mmol/L ethylenediaminetetraacetic acid (EDTA) at pH 7.0 and incubated at 4 ℃ for 24 h, yielding a maximum modification efficiency of 64.1%. The resulting product was purified to a purity of 94%. The free sulfhydryl content of β-LG decreased from 52.3 to 0.3 μmol/g after the site-specific PEGylation. It was demonstrated that mPEG-MAL was specifically conjugated with β-LG at the thiol group of Cys121. The antigenicity of β-LG increased by 25.9% after the cysteine-specific PEGylation, contrary to results previously obtained by modification at other amino acid positions. Accordingly, site-specific PEGylation can allow effective regulation of β-LG antigenicity.

Key words: β-lactoglobulin; polyethylene glycol; covalent modification; site-specific PEGylation; antigenicity

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