A sucrose-derived scaffold for multimerization of bioactive peptides

Abstract

A spherical molecular scaffold bearing eight terminal alkyne groups was synthesized in one step from sucrose. One or more copies of a tetrapeptide azide, either N3(CH2)5(C=O)-His-dPhe-Arg-Trp-NH2 (MSH4) or N3(CH2)5(C=O)-Trp-Met-Asp-Phe-NH2 (CCK4), were attached to the scaffold via the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Competitive binding assays using Eu-labeled probes based on the superpotent ligands Ser-Tyr-Ser-Nle-Glu-His-dPhe-Arg-Trp-Gly-Lys-Pro-Val-NH2 (NDP-α-MSH) and Asp-Tyr-Met-Gly-Trp-Met-Asp-Phe-NH2 (CCK8) were used to study the interactions of monovalent and multivalent MSH4 and CCK4 constructs with Hek293 cells engineered to overexpress MC4R and CCK2R. All of the monovalent and multivalent MSH4 constructs exhibited binding comparable to that of the parental ligand, suggesting that either the ligand spacing was inappropriate for multivalent binding, or MSH4 is too weak a binder for a second “anchoring” binding event to occur before the monovalently-bound construct is released from the cell surface. In contrast with this behavior, monovalent CCK4 constructs were significantly less potent than the parental ligand, while multivalent CCK4 constructs were as or more potent than the parental ligand. These results are suggestive of multivalent binding, which may be due to increased residence times for monovalently bound CCK4 constructs on the cell surface relative to MSH4 constructs, the greater residence time being necessary for the establishment of multivalent binding.

Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016

“…Solanesol-derived and sucrose-derived scaffolds were utilized to make both bivalent and tetravalent ligands attached to the His-DPhe-Arg-Trp tetrapeptide sequence [270, 271]. Moderate improvement in binding affinity at the hMC4R was observed, likely due to proximity effects and increasing the moles of pharmacophore present, but not indicative of cooperative or multivalent binding.…”

“…Moderate improvement in binding affinity at the hMC4R was observed, likely due to proximity effects and increasing the moles of pharmacophore present, but not indicative of cooperative or multivalent binding. The authors hypothesized their ligands may not possess the correct linker length or improperly presented the pharmacophores for cooperative binding [270, 271]. …”

Synthesis and bioactivity of MSH4 oligomers prepared by an A2+ B2 strategy

“…19 We have described multivalent constructs based on linear, 20–23 spherical, 24 and trigonal 25 scaffolds, some bearing variable ligand numbers and with variable ligand spacing. Much of this work (and the work of others 26–28 ) has focused on incorporation of the weakly binding tetrapeptide His-DPhe-Arg-Trp (MSH4) since cooperative binding leading to enhanced avidity is more evident when weakly binding ligands are utilized.…”

Demonstration of a sucrose-derived contrast agent for magnetic resonance imaging of the GI tract

“…To make our construct more stable and less complex, we elected to employ ether links to sucrose involving chains of the same or similar constitution. We recently demonstrated that small peptide ligands 19 and prodrugs 20 could be attached to a sucrose-derived scaffold by means of the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). As the next step toward development of targeted CAs, we report herein the synthesis of an untargeted, sucrose-derived CA and its use in magnetic resonance imaging of the GI tract.…”