Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.
Photochem Photobiol Sci. 2009 Dec;8(12):1701-7. doi: 10.1039/b9pp00018f. Epub 2009 Oct 19.
Demetalation kinetics of natural chlorophyll (Chl) d purified from Acaryochloris marina was first studied and compared with those of Chls a and b. The demetalation rate constant of Chl d, which possessed a formyl group at the 3-position, was five-fold smaller than that of Chl a possessing a vinyl group at the same position in aqueous acetone at the proton concentration of 1.2 x 10(-3) M at 25 degrees C. In contrast, the demetalation rate constant of Chl b possessing a formyl group at the 7-position was 26 times smaller than that of Chl a. The activation energy of demetalation reaction of Chl d was larger than that of Chl a, but smaller than that of Chl b. These indicate that the substitution effect of 3-formyl group on the acidic removal of central magnesium in Chls was smaller than that of 7-formyl group.
首次研究并比较了来自海洋盐杆菌的天然叶绿素 (Chl) d 的脱金属动力学与 Chl a 和 b 的脱金属动力学。在质子浓度为 1.2 x 10(-3) M 的水-丙酮中于 25°C 时，具有 3-位甲酰基的 Chl d 的脱金属速率常数比具有相同位置乙烯基的 Chl a 的脱金属速率常数小五倍。相比之下，具有 7-位甲酰基的 Chl b 的脱金属速率常数比 Chl a 小 26 倍。Chl d 脱金属反应的活化能大于 Chl a，但小于 Chl b。这些表明 3-位甲酰基对 Chl 中中心镁的酸性去除的取代效应小于 7-位甲酰基。
