G-protein Interactions with Receptor-Derived Peptides Chemisorbed on Gold

Interactions between the functional bovine brain G-protein and receptor-derived peptides chemically adsorbed on gold surfaces are studied. The peptides are designed to mimic the third ic-loop (aa 361-373) of the Alpha 2a-adrenergic receptor (α2AR). These segments are linked to a surface using the thiol−gold chemistry, and the protein interaction studies are conducted to investigate the key function of recognition. The chemical composition and binding strength of the peptide monolayers onto a gold surface are characterized using X-ray photoelectron spectroscopy and infrared (IR) spectroscopy. Strong molecular binding of the adsorbates to the gold surface is attained, and the presence of amide-related IR vibrations verified the composition of the peptides. Bovine brain G-protein adsorption studies on these molecular monolayers are performed using the surface plasmon resonance technique. The arginine-rich peptide, which is a direct mimicry of the receptor, has a higher affinity for G-protein than the lysine-rich and alanine-rich derived peptides, showing that arginine residue has special importance for the G-protein interaction with the receptor.