Specific Inclusion Mode of Guest Compounds in the Amylose Complex Analyzed by Solid State NMR Spectroscopy

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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℃ for 6h 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℃ for 1h. The formation of an inclusion compound was not observed when sealed-heating was performed at 50℃ for 6h. 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℃. 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.
社団法人日本薬学会の論文
2006-08-01