LANGMUIR-BLODGETT-FILMS OF RHODOPSIN - AN INFRARED SPECTROSCOPIC STUDY

Langmuir-Blodgett (LB) films of bovine rhodopsin were prepared and stu died using FTIR spectroscopy in the region between 700 and 4000 cm(-1) . A substantial decrease of lipids was found in LB films compared to s pread films. This suggested that most of the phospholipids surrounding the protein were expelled during the film compression. Moreover, the relatively high amide II/amide I ratio found in LB films indicates tha t the or-helices are oriented perpendicular to the film plane. The sec ondary structure of rhodopsin was estimated from the amide I spectrum. The content of a-helical structure obtained for rhodopsin in the spre ad and in the LB films was 70 and 67%, respectively, while that of P-s heets was about 13% either in LB or in spread films. These results sug gest that bovine rhodopsin, although losing most of its surrounding li pids when assembled in LB films, preserves its orientation and its sec ondary structure. (C) 1998 Published by Elsevier Science S.A. All righ ts reserved.