Specific inclusion mode of guest compounds in the amylose complex analyzed by solid state NMR spectroscopy.
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.
Tozuka
Yuichi
Y
Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. ytozuka@p.chiba-u.ac.jp
Takeshita
Aya
A
Nagae
Ayako
A
Wongmekiat
Arpansiree
A
Moribe
Kunikazu
K
Oguchi
Toshio
T
Yamamoto
Keiji
K
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
D046911:Macromolecular Substances; D000688:Amylose; D010129:4-Aminobenzoic Acid