Glycopeptide library

Scheme 4.77 Preparation of solid-phase glycopeptide library [411,412],...

Here, we present an overview of the aspects of the design, synthesis, analysis, and screening of combinatorial solid-phase glycopeptide libraries as compared to parallel glycopeptide arrays. 

As of this writing, there are presently only two examples of successful synthesis of glycopeptide libraries in the literature, and these have been generated using PEG-based resins (PEGA and POEPOP), thus enabling rapid solid phase screening of the library (see Sections 14.8 and 14.7.2). 

The development glycopeptide libraries obtained by the split-mix method is severely hampered by the lack of concurrent development of a general, facile separation and characterization technology. Some headway has been made with chemical coding of the libraries, but very few direct methods of analysis exist. One promising method that could be applied to the direct characterization of both types of libraries is mass spectrometry. More specifically, post-source-decay matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (PSD-MALDI-TOF-MS) and CID-FAB/MS/MS have been used to characterize glycopeptides.53-55... 

Figure 14.6 Representative mass spectrum showing ladder of a bisglycosylated glycopeptide obtained from screening of a glycopeptide library for the mannose binding protein. The nonanoic acid (Non) and tridecanoic acid (Tri) encode for Ser(Man) (Sm) and Asn(Man) (Nm), respectively.

Preparation and Analysis of Solid-Phase Glycopeptide Libraries... 

While parallel synthesis of arrays of glycopeptides is readily achieved by implementation of the building-block approach (Scheme 14.1, Strategy 2),101 glycopeptide library synthesis in a combinatorial manner via the split-mix method has yet to prove routine. The difficulty lies in the structural analysis of the vast number of compounds generated in picomolar quantities on a single bead. Whereas peptides on... 

Scheme 14.1 Strategies for glycopeptide library synthesis Strategy 1 chemical or enzymatic glycosylation of peptide or glycopeptide Strategy 2 the building-block approach. While enzymes have not yet been used in the solid-phase synthesis of glycopeptide libraries, several resin-bound glycopeptides have been glycosylated enzymatically.36,114...

Figure 14.8 (A) Screening of a glycopeptide library using a fluorescent-labeled lectin and ligands bound to PEGA beads. The acbve compounds are analysed by mass spectrometry. (B) FITC-labeled lectin binding to resin bound mannose could be inhibited by soluble glycopeptides obtained from library screen. Percent inhibition was quantified by recording of lectin fluorescence. Only every second well of the microtiter plate was used and nonfluorescent beads indicated good inhibitors.44...

Systematic investigations of mannose-binding proteins with clustered mannosides other than natural multiantennary oligosaccharides have been rather scarce until recently. However, using 6 -0-phosphorylated mannose disaccharide scaffolded on peptide templates using combinatorial glycopeptide libraries. 

M. Halkes, . H. Gotfredsen, M. Grotli, L. P. Miranda, J. O. Duus and M. Meldal, Solid-phase glycosylation of peptide templates and on-bead MAS-NMR analysis Perspectives for glycopeptide libraries, Chemistry-A European Journal, 2001, 7, 3584-3591. 

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