Hexanoylation of a VPAC2 receptor-preferring ligand markedly increased its selectivity and potency

Area of Science:

• Medicinal Chemistry
• Receptor Pharmacology
• Peptide Analog Design

Background:

• Vasoactive intestinal peptide (VIP) and its analogs are crucial in various physiological processes.
• Existing VIP analogs often lack sufficient selectivity between VPAC1 and VPAC2 receptors.
• Targeting specific VIP receptors is essential for developing selective therapeutic agents.

Purpose of the Study:

• To synthesize a novel VIP analog with enhanced affinity and selectivity for the VPAC2 receptor.
• To characterize the binding properties of the new analog against VPAC1, VPAC2, PAC1, and secretin receptors.
• To establish a highly potent and selective VIP analog for research applications.

Main Methods:

• Peptide synthesis involving site-specific mutations (A19, K27, K28) and N-terminal hexanoylation.
• Radioligand binding assays to determine receptor affinity (IC50 values).
• Comparative analysis of binding affinities across multiple receptor subtypes.

Main Results:

• The synthesized analog, Hexanoyl[A19,K(27,28)]VIP, exhibited high affinity for the VPAC2 receptor.
• The analog demonstrated significantly reduced affinity for the VPAC1 receptor.
• It showed minimal affinity for PAC1 and secretin receptors, with a 1000-fold preference for VPAC2 and an IC50 of 1 nM.

Conclusions:

• Hexanoyl[A19,K(27,28)]VIP is the most potent and selective VPAC2 receptor agonist reported to date.
• This analog represents a valuable pharmacological tool for studying VPAC2 receptor functions.
• The design strategy successfully achieved high VPAC2 receptor selectivity by combining specific mutations and hexanoylation.