Redox potential of chlorophyll d in vitro.
Biochim Biophys Acta
; 1767(6): 596-602, 2007 Jun.
Article
em En
| MEDLINE
| ID: mdl-17418087
ABSTRACT
Chlorophyll (Chl) d is a major chlorophyll in a novel oxygenic prokaryote Acaryochloris marina. Here we first report the redox potential of Chl d in vitro. The oxidation potential of Chl d was +0.88 V vs. SHE in acetonitrile; the value was higher than that of Chl a (+0.81 V) and lower than that of Chl b (+0.94 V). The oxidation potential order, Chl b>Chl d>Chl a, can be explained by inductive effect of substituent groups on the conjugated pi-electron system on the macrocycle. Corresponding pheophytins showed the same order; Phe b (+1.25 V)>Phe d (+1.21 V)>Phe a (+1.14 V), but the values were significantly higher than those of Chls, which are rationalized in terms of an electron density decrease in the pi-system by the replacement of magnesium with more electronegative hydrogen. Consequently, oxidation potential of Chl a was found to be the lowest among Chls and Phes. The results will help us to broaden our views on photosystems in A. marina.
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Base de dados:
MEDLINE
Assunto principal:
Clorofila
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Japão