フジサワ　アキオ   藤沢　章雄    所属   応用生物学部 応用生物学科    職種   教授
言語種別	英語
発行・発表の年月	2021/07
形態種別	学術論文
査読	査読あり
標題	Increase of oxidation rate of uric acid by singlet oxygen at higher pH
執筆形態	共著
掲載誌名	Journal of Clinical Biochemistry and Nutrition
掲載区分	国外
出版社・発行元	Society for Free Radical Research Japan
巻・号・頁	69(1),pp.16-19
総ページ数	4
担当範囲	Corresponding author
担当区分	責任著者
著者・共著者	Rina Horinouchi, Yorihiro, Yamamoto, Akio Fujisawa
概要	Singlet oxygen prefers to react with an electron-rich double bonds. We observed that the oxidation rate for uric acid with singlet oxygen increased with increasing pH and the oxidation rate dramatically was elevated at around pH 5.4 and 9.8, which are the acidity constants of uric acid, pKa1 and pKa2, respectively. Furthermore, we observed that the absorbance near 200 nm and the molar extinction coefficient (ɛ) increased with increasing pH, similar to the change in oxidation rate. Computer calculations by Chong [Chong, J Theor Comput Sci 2013; 1(1)] revealed that uric acid elongates its C=N conjugated diene structure with increasing pH. This is correlated with an increase in the UV absorbance of C=C double bonds near 200 nm, and may indicate higher electron density in the double bonds. Therefore, we concluded that the increased oxidation rate is due to elongation of the C=N conjugated polyene system at higher pH. On the other hand, the major products were 4-hydroxyallantoin and parabanic acid (hydrolyzed to oxaluric acid at pH 10.7), suggesting that the reaction pathways were the same regardless of pH. Finally, possible reaction schemes are presented.
論文（査読付）ファイル	DOWNLOAD