In Vitro Hydrolysis of Zinc Chlorophyllide a Homologues by a BciC Enzyme.
Biochemistry
; 59(49): 4622-4626, 2020 12 15.
Article
en En
| MEDLINE
| ID: mdl-33258578
ABSTRACT
Chlorosomes in green photosynthetic bacteria are the largest and most efficient light-harvesting antenna systems of all phototrophs. The core part of chlorosomes consists of bacteriochlorophyll c, d, or e molecules. In their biosynthetic pathway, a BciC enzyme catalyzes the removal of the C132-methoxycarbonyl group of chlorophyllide a. In this study, the in vitro enzymatic reactions of chlorophyllide a analogues, C132-methylene- and ethylene-inserted zinc complexes, were examined using a BciC protein from Chlorobaculum tepidum. As the products, their hydrolyzed free carboxylic acids were observed without the corresponding demethoxycarbonylated compounds. The results showed that the in vivo demethoxycarbonylation of chlorophyllide a by an action of the BciC enzyme would occur via two steps:
(1) an enzymatic hydrolysis of a methyl ester at the C132-position, followed by (2) a spontaneous (nonenzymatic) decarboxylation in the resulting carboxylic acid.
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MEDLINE
Asunto principal:
Clorofilidas
Idioma:
En
Revista:
Biochemistry
Año:
2020
Tipo del documento:
Article
País de afiliación:
Japón