title: Study of molecular aggregation of artificial amyloid in a langmuir monolayer by infrared spectroscopy.
abstract: A synthesized peptidolipid (C18IIGLM-NH2) comprised of a single C18-saturated hydrocarbon chain connected to the amino acid sequence IIGLM terminated with the NH2 group was spread on water, which formed a stable Langmuir monolayer. The Langmuir and Langmuir-Blodgett (LB) films have been characterized by measurements of surface pressure-area (pi-A) and surface potential-area (DeltaV-A) isotherms and infrared multiple-angle incidence resolution spectrometry (MAIRS). The Langmuir monolayer had a significantly larger limiting molecular area than that of a similar molecule of C18IIGLM-OH, which was reported in our previous study. The surface dipole moment analysis coupled with the pi-A isotherm suggested that the C18IIGLM-NH2 monolayer was extraordinarily stiff and the fundamental structure of the monolayer was brought about before the monolayer compression. The infrared MAIRS analysis of the C18IIGLM-NH2 LB film revealed that the backbone structure of the monolayer was the 'antiparallel' beta sheet aligned parallel to the substrate. Since the C18IIGLM-OH LB film was made of 'parallel' beta sheet with a random orientation, it has been found that the present C18IIGLM-NH2 Langmuir monolayer has a largely different monolayer structure, although the chemical structures are slightly different from each other by the terminal group only.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan. hasegawa@chem.titech.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sato
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kakuda
authors.forename: Changqing
authors.initials: C
authors.lastname: Li
authors.forename: Jhony
authors.initials: J
authors.lastname: Orbulescu
authors.forename: Roger M
authors.initials: RM
authors.lastname: Leblanc