Absolute stereochemistry of a 4 a-hydroxyriboflavin analogue of the key intermediate of the FAD-monooxygenase cycle.
Chemistry
; 20(15): 4386-95, 2014 Apr 07.
Article
em En
| MEDLINE
| ID: mdl-24590890
ABSTRACT
The biological action of flavoenzymes, such as flavin adenine dinucleotide (FAD)-containing monooxygenase, involves the formation of oxygenated flavin derivatives, such as 4 a-hydroperoxyflavin and 4 a-hydroxyflavin, in which a new center of chirality is created at the 4 a position during the enzymatic reactions. So far, the absolute configuration of this center of chirality in natural 4 a-oxygenated flavins has remained unknown in spite of its key importance for the diverse functions of flavoenzymes. Herein, we report the 4 a-hydroxy adduct 3 of 3-benzyl-5-ethyl-10-(tetraacetyl-D-ribityl)flavinium (1), one of the key intermediates involved in the enantioselective organocatalytic oxidation of sulfides to sulfoxides. The 4 a-hydroxyflavin diastereomers (+)-3 and (-)-3, separated by HPLC, were characterized by electronic circular dichroism (CD) spectroscopy. Their absolute configurations at the 4 a position were, for the first time, determined by comparing experimental CD spectra with those calculated by means of time-dependent density functional theory (TDDFT) on DFT-optimized structures obtained after an extensive conformation analysis.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxigenases
/
Riboflavina
Idioma:
En
Revista:
Chemistry
Assunto da revista:
QUIMICA
Ano de publicação:
2014
Tipo de documento:
Article