抄録
Integral membrane proteins, such as G-protein coupled receptors, play important roles in a variety of fundamental biological processes and have attracted much attention as potential targets for drug discovery. Therefore, development of novel methods to facilitate analysis and investigation of three-dimensional structures as well as biological functions of integral membrane proteins have been much needed. However, their limited solubility and self-aggregation in water make their manipulations difficult. For streamlining such tedious and time-consuming manipulations, we have synthesized artificial phospholipids as "scissor" molecules for integral membrane proteins. A "scissor" phospholipid (R,S)-1, bearing saturated alkyl chains as a membrane anchor and recognition site for the transmembrane domain, and an EDTA-Fe(III) complex as a protein cleavable polar head group, has been prepared by using an amidite coupling method between a phenolic head group (S)-4 and a phosphoroamidite derivative (R)-5a. Selective cleavage of viral integral membrane protein, hemagglutinin, with (R,S)-1 has been demonstrated. To improve the efficiency and site-selectivity of the cleavage reactions, we aimed to synthesize the artificial phospholipids possessing a variety of protein cleavable head groups. The key intermediates (R)-12a, b, possessing highly reactive oxyamino group, have been prepared via an amidite coupling of 10 with amidites (R)-5a, b. Successive conjugation of various head groups having formyl moiety with (R)-5a, b by oxime bond formation and deprotection of benzyl or cyanoethyl group provided 1,10-phenanthroline-Cu (R)-15, cyclen-Cu (R)-21 and imidazole tetherd phospholipids (R)-22, 23 in excellent yields.
