Chiral-phase HPLC separation of (divinyl-)protochlorophyllide-a enantiomers as key precursors in chlorophyll biosynthesis from their 132-stereoisomeric prime forms

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作   者：

Shiozaki, Mai;  Mizoguchi, Tadashi;  Harada, Jiro;  Hirose, Mitsuaki;  Tamiaki, Hitoshi; 

关键词：

NADPH;  Porphyrinoid;  ABSOLUTE-CONFIGURATION;  Enantiomer;  Racemization;  Stereochemistry;  Chromatography;  Circular dichroism; 

期刊名称：

Biochimica et biophysica acta. Bioenergetics

i s s n：

0005-2728

年卷期：

2023 年 1864 卷 2 期

页   码：

148960-148960

页   码：

摘   要：

Protochlorophyllide(PChlide)-a and its 8-vinylated analog, divinyl(DV)-PChlide-a, are common and essential intermediates in the biosynthesis of all naturally occurring chlorophyll (Chl) pigments. These porphyrinoid-type pigments have a single optically active (asymmetric) carbon atom at the 132-position, so their stereoisomers are (132R)- and (132S)-enantiomers. The former and latter are called (DV-)PChlide-a and (DV-)PChlide-a ', respectively. In this study, chiral-phase HPLC separation of enantiomeric (DV-)PChlides-a/a ' was demonstrated. The (132R)-enantiomeric PChlide-a was eluted more slowly than the corresponding (132S)-enantiomeric PChlide-a ' under the present HPLC conditions. On the other hand, the elution order of (132R)-DV-PChlide-a and (132S)-DVPChlide-a ' was reverse to that of PChlides-a/a '. After the separation of each enantiomer by the chiral-phase HPLC, the stereoisomeric configuration at the 132-position was characterized by means of circular dichroism spectroscopy. The present chiral-phase HPLC method enables us to evaluate optical purities of (DV-)PChlide-a species. For example, PChlide-a and/or DV-PChlide-a extracted from the spent medium and harvested cells of cultured purple photosynthetic bacterial mutants, the former of which has been often used as the source of (DV-) PChlide-a substrates for enzymatic reactions, were revealed to be mostly racemized, giving enantiomeric mixtures of (DV-)PChlides-a/a '.