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Solid Phase Synthesis and Secondary Structural Studies of (1→5) Amide-Linked Sialooligomers1

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journal contribution
posted on 23.01.1998, 00:00 authored by Lajos Szabo, Brenda L. Smith, Katherine D. McReynolds, Abby L. Parrill, Edwin R. Morris, Jacquelyn Gervay
A series of dimeric through octameric (1→5) amide-linked sialooligomers were prepared using solid-phase peptide methods on Rink resin with Fmoc protecting group chemistry. The oligomers were conjugated to ε-amino caproic acid in order to model membrane-bound conformations. The secondary structure of the oliogomers was probed with NH/ND exchange rates determined by NMR, and with circular dichroism. The combined structural studies show that a tetramer is required for ordered secondary structure, and that secondary structure is stabilized upon elongation to pentameric and hexameric species. Interestingly, the heptamer shows rapid NH/ND exchange rates; however, ordered secondary structure is restored in the octamer. These studies provide the first evidence that oligomers composed of constrained carbohydrate-derived amino acids form stable secondary structures in water.