Photoaffinity Labeling of a δ-Receptor Component of NG 108-15 Cells with a New Enkephalin Analog

Abstract

A new leucine-enkephalin analog containing p-azidophenylalanine was synthesized. It binds to the δ-opioid receptors of NG 108-15 cells with high affinity. Iodination of the compound decreased the affinity by 5 times, but the iodinated derivative still retains significant binding activity to the cells. Photochemical reactions revealed that the derivative predominantly labeled a 58 kilodaltons (kDa) polypeptide in the cells (possibly a δ-receptor component)