Preparation of phosvitin–dextran conjugates under high temperature in a liquid system

The conjugation reaction between phosvitin (Pv) and dextran (Dex) in an aqueous solution at the initial stage of Maillard reaction was investigated in this study. The formation of Pv–Dex conjugates was indirectly traced by measuring the absorbance at 200 nm in the UV-vis spectrophotometer. The content of free amino groups in the glycosylated Pv decreased to 77.4% after reaction for 6 h. The new band near the loading end of SDS-PAGE gel also suggested the high molecular weight products developed after conjugation. The shift of the main peak of Pv in size exclusion-high performance liquid chromatography from 9.16 min to 8.87 min and the minor peak from 6.56 min to 6.13 min confirmed the formation of covalent conjugates. Circular dichroism (CD) spectra demonstrated that significant changes of the secondary structure occurred to the grafted Pv. The optimum conjugation condition chosen was per Pv (5 mg/ml) glycosylated with 4-fold dextran (Mw, 40 kDa) at 100 °C for 6 h.

► The content of free amino groups in the glycosylated Pv decreased to 77.4% after reaction for 6 h at 100 °C.
► The main peak of the conjugates from SE-HPLC shifted from 9.16 min to 8.86 min.
► Significant changes occurred to the secondary structure of conjugates.
► The optimum glycosylation condition was Pv to 4-fold dextran (Mw, 40 kDa) at 100 °C for 6 h.