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BciC-Catalyzed C132 -Demethoxycarbonylation of Metal Pheophorbide a Alkyl Esters.
ChemBioChem ( IF 3.2 ) Pub Date : 2020-02-27 , DOI: 10.1002/cbic.201900745 Mitsuaki Hirose 1 , Misato Teramura 1 , Jiro Harada 2 , Hitoshi Tamiaki 1
ChemBioChem ( IF 3.2 ) Pub Date : 2020-02-27 , DOI: 10.1002/cbic.201900745 Mitsuaki Hirose 1 , Misato Teramura 1 , Jiro Harada 2 , Hitoshi Tamiaki 1
Affiliation
Bacteriochlorophyll c molecules self-aggregate to form large oligomers in the core part of chlorosomes, which are the main light-harvesting antenna systems of green photosynthetic bacteria. In the biosynthetic pathway of bacteriochlorophyll c, a BciC enzyme catalyzes the removal of the C132 -methoxycarbonyl group of chlorophyllide a, which possesses a free propionate residue at the C17-position and a magnesium ion as the central metal. The in vitro C132 -demethoxycarbonylations of chlorophyll a derivatives with various alkyl propionate residues and central metals were examined by using the BciC enzyme derived from one green sulfur bacteria species, Chlorobaculum tepidum. The BciC enzymatic reactions of zinc pheophorbide a alkyl esters were gradually suppressed with an increase of the alkyl chain length in the C17-propionate residue (from methyl to pentyl esters) and finally the hexyl ester became inactive for the BciC reaction. Although not only the zinc but also nickel and copper complexes were demethoxycarbonylated by the BciC enzyme, the reactions were largely dependent on the coordination ability of the central metals: Zn>Ni>Cu. The above substrate specificity indicates that the BciC enzyme would not bind directly to the carboxy group of chlorophyllide a, but would bind to its central magnesium to form the stereospecific complex of BciC with chlorophyllide a, giving pyrochlorophyllide a, which lacks the (132 R)-methoxycarbonyl group.
中文翻译:
BciC催化的金属Phphophorbide a烷基酯的C132-脱甲氧基羰基化。
细菌叶绿素c分子自聚集形成大量的寡聚体,位于绿体的核心部分,绿体是绿色光合细菌的主要光收集天线系统。在细菌叶绿素c的生物合成途径中,BciC酶催化去除叶绿素a的C132-甲氧基羰基,该叶绿素a在C17位具有游离丙酸酯残基,且镁离子为中心金属。通过使用衍生自一种绿色硫细菌物种Tekpidum的BciC酶,对具有各种丙酸烷基酯残基和中心金属的叶绿素a衍生物进行了体外C132-脱甲氧基羰基化反应。脱镁变色锌a烷基酯的BciC酶促反应随着C17-丙酸酯残基中烷基链长度的增加(从甲基到戊酯)而逐渐被抑制,最后己酯对BciC反应失去活性。尽管不仅锌,而且镍和铜络合物都被BciC酶脱甲氧基羰基化,但反应很大程度上取决于中心金属的配位能力:Zn> Ni> Cu。上述底物特异性表明,BciC酶不会直接结合至叶绿素a的羧基,但会与其中央镁结合形成BciC与叶绿素a的立体定向复合物,从而得到缺少(132 R)的焦叶绿素a。 -甲氧基羰基。
更新日期:2020-01-03
中文翻译:
BciC催化的金属Phphophorbide a烷基酯的C132-脱甲氧基羰基化。
细菌叶绿素c分子自聚集形成大量的寡聚体,位于绿体的核心部分,绿体是绿色光合细菌的主要光收集天线系统。在细菌叶绿素c的生物合成途径中,BciC酶催化去除叶绿素a的C132-甲氧基羰基,该叶绿素a在C17位具有游离丙酸酯残基,且镁离子为中心金属。通过使用衍生自一种绿色硫细菌物种Tekpidum的BciC酶,对具有各种丙酸烷基酯残基和中心金属的叶绿素a衍生物进行了体外C132-脱甲氧基羰基化反应。脱镁变色锌a烷基酯的BciC酶促反应随着C17-丙酸酯残基中烷基链长度的增加(从甲基到戊酯)而逐渐被抑制,最后己酯对BciC反应失去活性。尽管不仅锌,而且镍和铜络合物都被BciC酶脱甲氧基羰基化,但反应很大程度上取决于中心金属的配位能力:Zn> Ni> Cu。上述底物特异性表明,BciC酶不会直接结合至叶绿素a的羧基,但会与其中央镁结合形成BciC与叶绿素a的立体定向复合物,从而得到缺少(132 R)的焦叶绿素a。 -甲氧基羰基。