Induction and Characterization of a NADPH-Dependent Flavone Synthase from Cell Cultures of Soybean

1987 ◽  
Vol 42 (4) ◽  
pp. 343-348 ◽  
Author(s):  
Georg Kochs ◽  
Hans Grisebach
Keyword(s):  
Carbon Monoxide ◽  
Cell Cultures ◽  
Absolute Requirement ◽  
Isoflavone Synthase ◽  
Flavone Synthase ◽  
Flavone Synthase Ii ◽  
Stressed Cells ◽  
Cytochrome P 450 ◽  
Flavone Synthesis

Microsomal preparations from osmotically stressed soybean cells catalyze the conversion of (2S)-naringenin to apigenin in presence of NADPH. In contrast, such preparations from normal soybean cells or from elicitor-challenged cells catalyze the conversion of (2S)-naringenin to genistein (isoflavone synthase). It is concluded that osmotic stress of the cells causes a switch from isoflavone to flavone synthesis. The flavone synthase from osmotically stressed cells corresponds in its properties to the microsomal flavone synthase found in several flowers (G. Stotz and G. Forkmann, Z. Naturforsch. 36c, 737-741 (1981)) and differs from the flavone synthase I from parsley cell cultures which is a soluble Fe2+ and 2-oxoglutarate dependent dioxygenase. Flavone synthase II from soybean has an absolute requirement for NADPH and oxygen. It is inhibited by carbon monoxide in presence of oxygen and this inhibition is reversed by light. It is also inhibited by cytochrome c and by a number of cytochrome P-450 inhibitors. This and other properties show that flavone synthase II is a cytochrome P-450 dependent monooxygenase.

Molecular and biochemical characterization of torenia flavonoid 3′-hydroxylase and flavone synthase II and modification of flower color by modulating the expression of these genes

Plant Science ◽  
2002 ◽  
Vol 163 (2) ◽  
pp. 253-263 ◽  
Author(s):  
Yukiko Ueyama ◽  
Ken-ichi Suzuki ◽  
Masako Fukuchi-Mizutani ◽  
Yuko Fukui ◽  
Kiyoshi Miyazaki ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Flower Color ◽  
Flavone Synthase ◽  
Flavone Synthase Ii

Enzymatic Synthesis of 4′-and 3′, 4′ -Hydroxylated Flavanones and Flavones with Flower Extracts of Sinningia cardinalis

1987 ◽  
Vol 42 (11-12) ◽  
pp. 1193-1199 ◽  
Author(s):  
K. Stich ◽  
G. Forkmann
Keyword(s):  
Enzymatic Synthesis ◽  
Microsomal Fraction ◽  
Chalcone Synthase ◽  
Condensation Reaction ◽  
Flavonoid Biosynthesis ◽  
Hydroxylase Activity ◽  
Key Enzyme ◽  
Flavone Synthase ◽  
Flavone Synthase Ii ◽  
Cytochrome P 450

Flowers of Sinningia (syn. Rechsteineria) cardinalis contain glycosides of the flavones apigenin (4′-OH) and luteolin (3′,4′-OH) respectively, and of the related 3-deoxyanthocyanidins apigeninidin and luteolinidin. Studies on substrate specificity of the key enzyme of flavonoid biosynthesis, chalcone synthase, revealed that the 3′,4′-hydroxylated flavonoids are formed by hydroxylation of flavonoid compounds rather than by incorporation of caffeoyl-CoA into the flavonoid skeleton during the condensation reaction. In fact, flavonoid 3′-hydroxylase activity could be demonstrat­ed in the microsomal fraction of the flower extracts. The enzyme catalyses hydroxylation of naringenin and apigenin in the 3′-position to eriodictyol and luteolin, respectively, with NADPH as cofactor. Besides flavanone 3′-hydroxylase a further NADPH-dependent enzyme activity (flavone synthase II) was observed in the microsomal fraction catalysing the oxidation of naringenin to apigenin and of eriodictyol to luteolin. The Cytochrome P-450 inhibitor ancymidol was found to abolish completely flavone synthase II activity, whereas flavonoid 3′-hydroxylase activity was not impaired.

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis

1984 ◽  
Vol 107 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Itaru Kojima ◽  
Etsuro Ogata ◽  
Hiroshi Inano ◽  
Bun-ichi Tamaoki
Keyword(s):  
Carbon Monoxide ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Manner ◽  
In Vitro Production ◽  
Mitochondrial Preparation ◽  
Final Reaction ◽  
Vitro Production ◽  
Dose Dependent ◽  
Cytochrome P 450

Abstract. Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000. SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H ]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

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