Gastric Inhibitory peptide (3-42) (human) / GIP (3-42), human

• Handling and Storage of Synthetic Peptides
• Material Safety Data Sheets (MSDS)

Batch to batch variation of the purity

Because the N-terminus is essential for GIP receptor (GIPR) activation, truncation abolishes intrinsic activity: GIP(3-42) does not stimulate cAMP accumulation in GIPR-expressing COS-7 cells even at 1 µM, and does not trigger insulin secretion from rat islets or the perfused pancreas. It retains receptor binding, though with reduced affinity (IC50 ~22 nM vs 5.2 nM for GIP(1-42)), and acts as a weak, surmountable antagonist, shifting the GIP(1-42) concentration-response curve rightward (IC50 92–731 nM depending on agonist concentration). In isolated perfused rat pancreas, inhibition of insulin output required ≥50-fold molar excess.

In anesthetized pigs with DPP-4 inhibited, co-infusion at postprandial concentrations did not alter glucose, insulin or glucagon responses. GIP(3-42) is therefore a low-potency antagonist in vitro but not a physiological antagonist in vivo; its C-terminal 31-42 extension further weakens antagonism relative to GIP(3-30)NH2.

• Gabe MBN, van der Velden WJC, Smit FX, Gasbjerg LS, Rosenkilde MM. Molecular interactions of full-length and truncated GIP peptides with the GIP receptor - A comprehensive review. Peptides. 2020;125:170224. doi:10.1016/j.peptides.2019.170224
• Deacon CF, Plamboeck A, Rosenkilde MM, de Heer J, Holst JJ. GIP-(3–42) does not antagonize insulinotropic effects of GIP at physiological concentrations. Am J Physiol Endocrinol Metab 291: E468-E475, 2006. doi: 10.1152/ajpendo.00577.2005.
• V.A.Gault et al., J. Endocrinol., 175, 525 (2002)

Trifluoroacetic acid (TFA) is a common counterion from the purification process using High-Performance Liquid Chromatography (HPLC). The presence of TFA can affect the peptide's net weight, appearance, and solubility.

Impact on Net Weight: The TFA salt contributes to the total mass of the product. In most cases, the peptide content constitutes >80% of the total weight, with TFA accounting for the remainder.

Solubility: TFA salts generally enhance the solubility of peptides in aqueous solutions.

In Biological Assays: For most standard in vitro assays, the residual TFA levels do not cause interference. However, for highly sensitive cellular or biochemical studies, please be aware of its presence.