Studies on Columnidin Biosynthesis with Flower Extracts from Columnea hybrida

1988 ◽  
Vol 43 (3-4) ◽  
pp. 311-314 ◽  
Author(s):  
K. Stich ◽  
G. Forkmann
Keyword(s):  
Enzyme Preparation ◽  
Microsomal Fraction ◽  
Chalcone Synthase ◽  
Hydroxyl Group ◽  
Soluble Enzyme ◽  
Hydroxylase Activity ◽  
Flavone Synthase ◽  
Flavone Synthase Ii ◽  
Characteristic 3 ◽  
Ring Hydroxylation

Columnidin, the characteristic 3-deoxyanthocyanidin of some Columnea species, possesses the 3′,4′-B-ring hydroxylation pattern of luteolinidin and an additional hydroxyl group at the A-ring, most likely in the 8-position. Studies on substrate specificity of chalcone synthase and flavanone 4-reductase and the demonstration of high flavonoid 3′-hydroxylase activity revealed that the 3′-hydroxyl group of the B-ring of columnidin is introduced at the flavanone stage by hydroxylation of naringenin to eriodictyol. Enzymatic hydroxylation of the A-ring, however, could neither be observed with soluble enzyme preparation nor with microsomal fraction. Most probably this step first occurs at the anthocyanidin level. Besides flavonoid 3′-hydroxylase the microsomal fraction of Columnea flower extracts contains flavone synthase II activity catalysing desaturation of flavanones to flavones with NADPH as co-factor. The presence of some apigenin, appreciable amounts of luteolin and of the 3′,4′-hydroxylated flavan-4-ol luteoforol in the flowers confirm the enzymatic data.

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.

Genetic Control of Flavanone 3-Hydroxylase Activity and Flavonoid 3′-Hydroxylase Activity in Antirrhinum majus (Snapdragon)

1981 ◽  
Vol 36 (5-6) ◽  
pp. 411-416 ◽  
Author(s):  
G. Forkmann ◽  
G. Stotz
Keyword(s):  
Genetic Control ◽  
Microsomal Fraction ◽  
Hydroxyl Group ◽  
Antirrhinum Majus ◽  
Clear Correlation ◽  
Soluble Enzyme ◽  
Hydroxylase Activity ◽  
Anthocyanin Pathway

Abstract In flower extracts of defined genotypes of Antirrhinum majus, two different hydroxylases were found catalysing the hydroxylation of naringenin and eriodictyol in the 3-position and of naringenin in the 3′-position. The 3-hydroxylase is a soluble enzyme and belongs according to its cofactor requirement to the 2-oxoglutarate-dependent dioxygenases. Investigations on different genotypes revealed a clear correlation between block of the anthocyanin pathway by recessive alleles of the gene inc and a complete lack of 3-hydroxylase activity. Chemogenetic studies on different genotypes suggested that the 3′-hydroxyl group of the B-ring of flavonoids is introduced at the stage of C15 intermediates. The corresponding 3′-hydroxylase was found to be localized in the microsomal fraction and required NADPH as cofactor. In confirmation of the chemogenetic studies, a strict correlation was found between 3′-hydroxylase activity and the gene eos which is known to control the hydroxylation of flavones, flavonols and anthocyanins in the 3′-position. These results are similar to those previously obtained with Matthioia incana.

scholarly journals Unraveling the Biochemical Base of Dahlia Flower Coloration

2008 ◽  
Vol 3 (8) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Heidi Halbwirth ◽  
Gerlinde Muster ◽  
Karl Stich
Keyword(s):  
Chalcone Synthase ◽  
Flower Color ◽  
Chalcone Isomerase ◽  
Anthocyanin Content ◽  
Anthocyanin Accumulation ◽  
Enzyme Preparations ◽  
Yellow Color ◽  
Flavone Synthase ◽  
Flavone Synthase Ii ◽  
Related Compounds

Dahlia ( Dahlia variabilis) exists in a dazzling array of cultivars, showing red, orange, magenta, lilac, yellow and white flower color, which is exclusively based on the presence of flavonoids and biochemically related compounds. Red hues (red, orange, magenta, lilac) are a result of anthocyanin accumulation in varying concentration and composition, while a yellow color is based on the formation of 6′-deoxychalcones in the petals. Red dahlia pigments are all derived from pelargonidin and cyanidin. Delphinidin derivatives are not formed due to the absence of flavonoid 3′,5′-hydroxylase in dahlia petals, which provides an explanation for the lack of blue dahlia flowers. Orange, lilac and rose cultivars are characterized by a lower anthocyanin content compared to many red cultivars. We investigated 198 cultivars for the presence of flavonoid enzymes. The activities of chalcone isomerase (CHI), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), flavanone 3-hydroxylase (FHT), flavone synthase II (FNSII), flavonol synthase (FLS) and flavonoid 3′-hydroxylase (F3′H) were demonstrated in enzyme preparations of dahlia petals. CHI accepted 6′-hydroxychalcones as substrates, but did not catalyze the conversion of 6′-deoxychalcones to the corresponding flavanones. White cultivars were frequently characterized by the lack of DFR activity, whereas in many yellow cultivars neither FHT nor DFR activity could be shown.

Anthocyanin Biosynthesis in Flowers of Matthiola incana Flavanone 3-and Flavonoid 3′-Hydroxylases

1980 ◽  
Vol 35 (9-10) ◽  
pp. 691-695 ◽  
Author(s):  
G. Forkmann ◽  
W. Heller ◽  
H. Grisebach
Keyword(s):  
Microsomal Fraction ◽  
Anthocyanin Biosynthesis ◽  
Wild Type Allele ◽  
Soluble Enzyme ◽  
Wild Type ◽  
Hydroxylase Activity ◽  
Enzyme Preparations ◽  
Type Allele ◽  
Matthiola Incana

Abstract Enzyme preparations from flowers of defined genotypes of Matthiola incana contain two dif­ ferent hydroxylases for hydroxylation of naringenin in the 3-and 3′-position, respectively. The 3-hydroxylase is a soluble enzyme and requires as cofactors 2-oxoglutarate, Fe2+ and ascorbate. Besides naringenin eriodictyol is a substrate for the 3-hydroxylase. The 3′-hydroxylase is localized in the microsomal fraction and requires NADPH as cofactor. Naringenin and dihydro-kaempferol but not 4-coumarate or 4-coumaroyl-CoA are substrates for this enzyme. 3′-Hydroxylase activity is present only in genetic lines of M. incana with the wild-type allele b+.

scholarly journals Interaction of soluble glucosyl- and mannosyl-transferase enzyme activities in the synthesis of a glucomannan

1972 ◽  
Vol 129 (3) ◽  
pp. 645-655 ◽  
Author(s):  
J. S. Heller ◽  
C. L. Villemez
Keyword(s):  
Enzyme Activity ◽  
Enzyme Activities ◽  
Enzyme Preparation ◽  
The Other ◽  
Acceptor Molecule ◽  
Soluble Enzyme ◽  
Phaseolus Aureus ◽  
Polymeric Product ◽  
Sugar Nucleotide ◽  
Solubilized Enzyme

A neutral-detergent-solubilized-enzyme preparation derived from Phaseolus aureus hypocotyls contains two types of glycosyltransferase activity. One, mannosyltransferase enzyme activity, utilizes GDP-α-d-mannose as the sugar nucleotide substrate. The other, glucosyltransferase enzyme activity, utilizes GDP-α-d-glucose as the sugar nucleotide substrate. The soluble enzyme preparation catalyses the formation of what appears to be a homopolysaccharide when either sugar nucleotide is the only substrate present. A β-(1→4)-linked mannan is the only polymeric product when only GDP-α-d-mannose is added. A β-(1→4)-linked glucan is the only polymeric product when only GDP-α-d-glucose is added. In the presence of both sugar nucleotides, however, a β-(1→4)-linked glucomannan is formed. There are indications that endogenous sugar donors may be present in the enzyme preparation. There appear to be only two glycosyltransferases in the enzyme preparation, each catalysing the transfer of a different sugar to the same type of acceptor molecule. The glucosyltransferase requires the continual production of mannose-containing acceptor molecules for maintenance of enzyme activity, and is thereby dependent upon the activity of the mannosyltransferase. The mannosyltransferase, on the other hand, does not require the continual production of glucose-containing acceptors for maintenance of enzyme activity, but is severely inhibited by GDP-α-P-glucose. These properties promote the synthesis of β-(1→4)-linked glucomannan rather than β-(1→4)-linked glucan plus β-(1→4)-linked mannan when both sugar nucleotide substrates are present.

Studies on the effects of magnesium ion and propranolol on iris muscle phosphatidate phosphohydrolase

1984 ◽  
Vol 62 (2-3) ◽  
pp. 170-177 ◽  
Author(s):  
Ata A. Abdel-Latif ◽  
Jack P. Smith
Keyword(s):  
Smooth Muscle ◽  
Divalent Cation ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Divalent Cations ◽  
Dependent Manner ◽  
Soluble Enzyme ◽  
Microsomal Enzyme ◽  
Time Intervals ◽  
Phosphatidate Phosphohydrolase

The properties, subcellular distribution, and the effects of Mg2+ and propranolol on phosphatidate phosphohydrolase (EC 3.1.3.4) from rabbit iris smooth muscle have been investigated. The particulate and soluble (0–30% (NH4)2SO4 fraction) enzymes were assayed using aqueous phosphatidate dispersions and membrane-bound phosphatidate as substrates, respectively. When measured with aqueous substrate, activity was detected in both the particulate and soluble fractions, with the highest relative specific activity found in the microsomal fraction. Maximum dephosphorylation by the microsomal enzyme was about 1100 nmol of inorganic phosphate released/h per milligram protein and occurred at pH 7.0–7.5. In general Mg2+ inhibited the phosphohydrolase activity of the microsomal fraction and stimulated that of the soluble fraction, and the effects of the divalent cation on both of these activities were reversed by propranolol. The microsomal enzyme was slightly stimulated by deoxycholate and inhibited by the divalent cations Mg2+, Ca2+, and Mn2+ at concentrations > 0.25 mM. In contrast, the soluble enzyme was stimulated by Mg2+. Inhibition of the microsomal enzyme by Mg2+ (0.5 mM) was reversed by both EDTA, which also stimulated at higher concentrations (1 mM), and propranolol (0.1–0.2 mM). The inhibitory effect of Ca2+ on the enzyme was not reversed by propranolol. In the absence of Mg2+, the microsomal enzyme was inhibited by propranolol in a dose-dependent manner, and both in the absence and presence of the divalent cation the soluble enzyme was inhibited by the drug in a similar manner. These data suggest that the cationic moiety of propranolol may act by competing at the Mg2+-binding sites. Addition of propranolol (0.2 mM) to iris muscle prelabelled with [14C]arachidonic acid increased accumulation of [14C]phosphatidic acid at all time intervals (2.5–90 min) and brought about a corresponding initial decrease in the formation of [14C]diacylglycerol at short time intervals (2.5 min), thus implicating the phosphohydrolase as a possible site of action of the drug on glycerolipid metabolism in this tissue. In addition to reporting on the characteristics and distribution of phosphatidate phosphohydrolase in the iris smooth muscle, the data presented add further support to our hypothesis that propranolol redirects glycerolipid metabolism in the iris by exerting multiple effects on the enzymes involved in their biosynthesis.

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

Conversion of Flavanone to Flavone, Dihydroflavonol and Flavonol with an Enzyme System from Cell Cultures of Parsley

1981 ◽  
Vol 36 (9-10) ◽  
pp. 742-750 ◽  
Author(s):  
L. Britsch ◽  
W. Heller ◽  
H. Grisebach
Keyword(s):  
Microsomal Fraction ◽  
Specific Activity ◽  
Enzyme System ◽  
High Specific Activity ◽  
Cell Suspension Cultures ◽  
Soluble Enzyme ◽  
Enzyme Preparations ◽  
Malonyl Coa ◽  
In Vitro Biosynthesis

Abstract Soluble enzyme preparations from irradiated cell suspension cultures of parsley (Petroselinum hortense Hoffm.) catalyse the conversion of flavanone to flavone, dihydroflavonol and flavonol. These reactions require 2-oxoglutarate, Fe2+ and ascorbate as cofactors. In the presence of these cofactors conversion of dihydroflavonol to flavonol was also observed. With this system in vitro biosynthesis of radioactive flavone, dihydroflavonol and flavonol from [2-14C]malonyl-CoA and 4-coumaroyl-CoA in good yield and with high specific activity is possible.We postulate that synthesis of flavone and flavonol from flavanone proceeds via 2-hydroxy-and 2,3-dihydroxyflavanone, respectively, with subsequent dehydration.The microsomal fraction of the parsley cells contains an NADPH-dependent flavanone 3'-hydroxylase.

scholarly journals Binding of radioiodinated propylthiouracil to rat liver microsomal fractions. Stimulation by substrates for iodothyronine 5′-deiodinase

1979 ◽  
Vol 183 (1) ◽  
pp. 167-169 ◽  
Author(s):  
T J Visser ◽  
E Van Overmeeren
Keyword(s):  
Rat Liver ◽  
Enzyme Preparation ◽  
Microsomal Fraction ◽  
Sodium Sulphite ◽  
Enzyme Complex ◽  
Deiodinase Activity ◽  
Liver Microsomal Fraction ◽  
Thiouracil Derivatives

Previous studies have shown that 2-thiouracil derivatives are uncompetitive inhibitors of iodothyronine 5′-deiodinase activity of rat liver microsomal fraction. Therefore the interaction of radioiodinated 6-propyl-2-thiouracil with rat liver microsomal fraction and the effect of substrate, cofactor and other inhibitors of 5′-deiodinase activity activity were investigated. It was found that micromolar concentrations of, in order of increasing potency, 3,5-diiodotyrosine, thyroxine, 3,3′,5′-tri-iodothyronine and 3′,5′-di-iodothyronine significantly enhanced binding of 5-[125I]iodo-6-propyl-2-thiouracil to the enzyme preparation. This stimulation was not seen in the presence of 1 mM dithiothreitol, 0.1 mM-6-propyl-2-thiouracil, 0.1 mM-6-propyl-2-thiouracil, 0.1 M-2-mercapto-1-methylimidazole or 1 mM-sodium sulphite. These results support the hypothesis that thiouracil derivatives inhibit 5′-deiodinase activity by forming a mixed disulphide with an intermediate enzyme complex, probably a sulphenyl iodide.

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