Microwave-assisted solid-phase synthesis of lactosylated peptides for food analytical application

The lactosylation of whey proteins affects their properties, especially their allergenicity and nutritional value, which matters in infant feeding. The quantification of lactosylated peptides requires analytically pure standards which are not commercially available. Herein, we proposed a fast, simple, and efficient protocol for the synthesis of lactosylated peptides on solid support based on microwave-assisted synthesis combined with boronate affinity chromatography utilizing the functionalized resin developed in our research group. We have used our method to synthesize identified modified peptides derived from β-lactoglobulin in tryptic digestion. Thus, the standard peptides contain the dabcyl moiety for determination of the amount in a sample and a cleavable linker to obtain tryptic analogs of β-lactoglobulin. Moreover, for the first time, we applied the functionalized resin to enrich the sample of human serum albumin lactosylated in vitro, into lactosylated peptides.