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Carbopeptides: chemoselective ligation of peptide aldehydes to an aminooxy‐functionalized D‐galactose template

Multifunctional, topological template molecules such as linear and cyclic peptides have been used for the attachment of peptide strands to form novel protein models of, for example, 4‐α‐helix bundles. The concept of carbohydrates as templates for de novo design of potential protein models has been previously described and these novel chimeric compounds were termed carbopeptides. Here, a second generation strategy in which carbopeptides are synthesized by chemoselective ligation of a peptide aldehyde to an aminooxy‐functionalized α‐D‐galactopyranoside is described. This template was prepared by per‐O‐acylation of methyl α‐D‐galactopyranoside with N,N‐Boc2‐aminooxyacetic acid to form a tetra‐functionalized template, followed by treatment with TFA‐CH2Cl2 to release the aminooxy functionality. The peptide aldehydes Fmoc‐Ser‐Gly‐Gly‐H and H‐Ala‐Leu‐Ala‐Lys‐Leu‐Gly‐Gly‐H were synthesized by a BAL strategy. Four identical copies of peptide aldehyde were smoothly attached to the template by chemoselective ligation to form a 2.1 and a 2.9 kDa carbopeptide, respectively. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.