Synthetic studies of membrane proteins: synthesis of the C-terminal region of opioid receptor-like 1

摘要

The thioester method and the native chemical ligation method have been successfully used in the preparation of a variety of peptides. These ligation methodologies are most effective in the preparation of a polypeptide that is difficult to obtain by biological means. Membrane proteins are representative of such proteins. It is well known that the slow progress in the field of membrane protein research is due to difficulties in sample preparation. Therefore chemical synthesis based on ligation chemistry can be a powerful technique for the preparation of membrane proteins. Based on the accumulated knowledge of ligation chemistry, there is a chance that a methodology for the preparation of membrane protein, especially of a polytopic membrane protein, can be generalized. In order to establish a strategy for membrane protein synthesis based on ligation chemistry, more challenges must be made for the efficient preparation of transmembrane peptide thioesters to diminish the restriction on the amino acid sequence in the coupling site and to optimize conditions for the ligation reaction. For this purpose, we initiated an investigation of the synthesis of a polytopic membrane protein using opioid receptor-like 1 (ORL1) as a model compound. ORL1, of human origin, is considered to be a G protein coupled receptor. The protein is comprised of seven transmembrane domains and plays a crucial role in signal transduction in cells.