| Abstract
| - Structural analysis of minimally sized lectins will offer insights into fundamentals ofintermolecular recognition and potential for biomedical applications. We thus moved significantly beyondthe natural limit of lectin size to determine the structure of synthetic mini-lectins in solution, theircarbohydrate selectivity and the impact of ligand binding on their conformational behavior. Using threedisaccharide (Thomsen-Friedenreich antigen; Galβ1,3GalNAcα1,R)-binding pentadecapeptides withoutinternal disulfide bridges as role models, we successfully tested a combined strategy with differenttechniques of NMR spectroscopy, electrospray ionization mass spectrometry, and molecular modeling. Insolution, the peptides invariably displayed flexibility with rather limited restrictions, shown by NMRexperiments including nearly complete resonance assignments and molecular dynamics simulations. Theoccurrence of aromatic/nonpolar amino acids in the sequence did not lead to formation of a hydrophobiccore known from microbial chitinase modules. Selectivity of disaccharide binding was independentlyobserved by mass spectrometry and NMR analysis. Specific ligand interaction yielded characteristic NMRsignal alterations but failed to reduce conformational flexibility significantly. We have thereby proveneffectiveness of our approach to analyze even low-affinity interactions (not restricted to carbohydrates asligands). It will be useful to evaluate the impact of rational manipulation of lead peptide sequences.
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