title: Specific inclusion mode of guest compounds in the amylose complex analyzed by solid state NMR spectroscopy.
abstract: The inclusion compound formation between linear amylose of molecular weight 102500 (AS100) and p-aminobenzoic acid (PA) during the sealed-heating process was investigated by powder X-ray diffractometry, infrared spectroscopy and solid state NMR spectroscopy. Sealed-heating of AS100 and PA at 100 degrees C for 6 h provided an inclusion compound with 6(1)-helix structure, while a 7(1)-helix structure was found when sealed-heating was carried out at 150 degrees C for 1 h. The formation of an inclusion compound was not observed when sealed-heating was performed at 50 degrees C for 6 h. The 7(1)-helix inclusion compound maintained its structure even during storage at high temperature while the 6(1)-helix inclusion compound decomposed and returned to the original V(a)-amylose upon heating to 180 degrees C. Quantitative determination revealed that one PA molecule could be included per one helical turn of AS100 for both 6(1)-helix and 7(1)-helix inclusion compounds. Solid state NMR spectroscopy suggested that PA molecules were included in the amylose helix core in the 7(1)-helix inclusion compound, while in the case of 6(1)-helix inclusion compound, PA molecules were accommodated in the interstices between amylose helices. Moreover, the inclusion compound formation by sealed-heating of AS100 was also observed when using PA analogues as guest compounds. The binding ratio of AS100 and PA analogues varied depending on the size of guest molecules.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. ytozuka@p.chiba-u.ac.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tozuka
authors.forename: Aya
authors.initials: A
authors.lastname: Takeshita
authors.forename: Ayako
authors.initials: A
authors.lastname: Nagae
authors.forename: Arpansiree
authors.initials: A
authors.lastname: Wongmekiat
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Moribe
authors.forename: Toshio
authors.initials: T
authors.lastname: Oguchi
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry*; D000688:Amylose / Q000737:chemistry*; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008956:Models, Chemical; D015394:Molecular Structure; D033362:Powder Diffraction; D013055:Spectrophotometry, Infrared
chemical_list: D046911:Macromolecular Substances; D000688:Amylose; D010129:4-Aminobenzoic Acid