GlyNest and CASPER: two independent approaches to estimate (1)H and (13)C NMR shifts of glycans available through a common web-interface

GlyNest and CASPER () are two independent services aiming to predict (1)H- and (13)C-NMR chemical shifts of glycans. GlyNest estimates chemical shifts of glycans based on a spherical environment encoding scheme for each atom. CASPER is an increment rule-based approach which uses chemical shifts of the free reducing monosaccharides which are altered according to attached residues of an oligo- or polysaccharide sequence. Both services, which are located on separate, distributed, servers are now available through a common interface of the GLYCOSCIENCES.de portal (). The predictive ability of both techniques was evaluated for a test set of 155 (13)C and 181 (1)H spectra of assigned glycan structures. The standard deviations between experimental and estimated shifts ((1)H; 0.081/0.102; (13)C 0.763/0.794; GlyNest/CASPER) are comparable for both methods and significantly better than procedures where stereochemistry is not encoded. The predictive ability of both approaches is in most cases sufficiently precise to be used for an automatic assignment of NMR-spectra. Since both procedures work efficiently and require computation times in the millisecond range on standard computers, they are well suited for the assignment of NMR spectra in high-throughput glycomics projects. The service is available at .