Residue configuration designation structure

The IUPAC-IUBMB short form symbolism18 2-Carb-38.5 is used here and elsewhere in this chapter for designation of oligosaccharide structures. Parent monosaccharide residues are the d enantiomers except for IdoA, which is the l enantiomer. Uronic acid residues modified by 44-unsaturation are prefixed by A4tS, and the associated anomeric symbol relates to the configuration at the 5-position of that residue before 4,5-elimination. The abbreviation HexA is used to denote either d-G1cA or L-IdoA. 

Using a bipyridine-based template, Kelly and coworkers were able to stabilize a / -sheet like structure by the coordination of the peptide-modified bipyridine (bpy) to a Cu(II) center. [8] The 6,6 -bis-(acylamino)-2,2 -bipyridine-based peptide 3 is designed to promote a -sheet structure upon Cu(II) binding. This template was chosen because the distance between the chains in the cisoid conformation is ca. 5.2 A, which is similar to the distance between the two strands in )9-sheet structures. In the uncoordinated state, the peptide-modified bpy adopts a transoid configuration to minimize steric interactions. The cisoid conformation has to be adopted in order for efficient Cu(II) binding (4) and hence the peptide residues will be forced in a spacial arrangement favoring y9-sheet formation (Fig. 1). 

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