A simplified procedure for gram-scale production of sialylglycopeptide (SGP) from egg yolks and subsequent semi-synthesis of Man3GlcNAc oxazoline

• An optimized procedure for gram-scale production of egg-yolk SGP.
• Simplified extraction and purification of SGP avoiding complicated processes.
• The first semi-synthesis of N-glycan core Man3GlcNAc oxazoline from SGP.
• This work facilitates the chemoenzymatic synthesis of various glycoconjugates.

Heterogeneity of glycan structures in native glycoconjugates always hampers precise studies on carbohydrate-involved biological functions. To construct homogeneous glycoconjugates from natural resource of homogeneous glycans is therefore a practical approach to solve this problem. We report here an optimized procedure for gram-scale production of sialylglycopeptide (SGP) containing a disialyl biantennary complex-type N-glycan from egg yolks. Our new procedure simplified the extraction process by treating the egg yolk powder with 40% acetone, avoiding massive emulsification, high-speed centrifugation, and sophisticated chromatography in reported methods. Subsequent semi-synthesis of the N-glycan core Man3GlcNAc oxazoline from SGP was accomplished for the first-time via glyco-trimming and successive oxazoline formation. This efficient semi-synthesis provides an alternative to the pure chemical approach that involves multi-step total synthesis and facilitates the application of endo-glycosidase-enabled chemoenzymatic synthesis of various homogeneous glycoconjugates.

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