Extended sugar-assisted glycopeptide ligations: development, scope, and applications

Area of Science:

• Biochemistry
• Organic Chemistry
• Glycoscience

Background:

• Sugar-assisted ligation (SAL) is a novel method for synthesizing glycopeptides.
• A significant portion (53%) of O-glycosylation sites are incompatible with standard SAL.
• This limitation hinders the synthesis of diverse naturally occurring glycopeptides.

Purpose of the Study:

• To develop an extended SAL method to overcome limitations of the original SAL technique.
• To broaden the applicability of SAL for synthesizing a wider range of glycopeptides.
• To improve the efficiency and scope of glycopeptide synthesis.

Main Methods:

• Screening of a glycoprotein database to identify limitations of SAL.
• Development and application of extended SAL methods with N-terminal amino acid extensions.
• Kinetic analysis and molecular dynamics simulations (AMBER9) to understand reaction mechanisms.
• Testing the tolerance of extended SAL to various amino acid combinations.

Main Results:

• Extended SAL facilitates ligation reactions with peptide thioesters, yielding products in good yields.
• Glycopeptide extension slows ligation rates, rationalized by increased distance between reactive sites.
• Extended SAL methods demonstrate broad amino acid tolerance at ligation junctions.
• The enhanced method allows utilization of 95% of O-linked glycosylation sites.

Conclusions:

• Extended SAL significantly expands the utility of SAL for synthesizing diverse glycopeptides and glycoproteins.
• The method is valuable for producing naturally occurring glycopeptides, including those found in cancer-associated glycoproteins like MUC1.
• This advancement offers a powerful tool for glycopeptide and glycoprotein synthesis.