VIP is an endogenous 28?amino?acid neuropeptide distributed across gastrointestinal tract, nervous system and immune tissues. This amphipathic peptide acts as a dual messenger, triggering downstream signalling upon binding to VPAC family GPCR receptors. Compared with many short synthetic peptides, its longer full?length sequence brings higher possibility of partial hydrolysis and fragment impurities throughout synthesis and storage.

Deletion fragments and oxidative modification on methionine residue are the primary by?products monitored during production. Mass spectrometry detection validates complete intact peptide chain, while HPLC separates oxidized variants to guarantee experimental reliability. Researchers utilise VIP for smooth?muscle relaxation related assays, neuro?immune crosstalk models, cytokine?release observation and receptor?ligand interaction research.

Methionine within the sequence is sensitive to oxygen?driven oxidation. Minimize air exposure during sample handling. Lyophilized powder maintains stability under frozen dark sealed condition. Once dissolved, prepare single?use aliquots right away. Avoid repeated freeze?thaw cycles, which accelerate methionine oxidation and lead to loss of biological activity for subsequent experiments.