Autocatalytic inactivation of plant cytochrome P-450 enzymes: Selective inactivation of cinnamic acid 4-hydroxylase from Helianthus tuberosus by 1-aminobenzotriazole

Reichhart, Danièle; Simon, Annick; Durst, Francis; Mathews, James; Montellano, Paul R. Ortiz de

doi:10.1016/0003-9861(82)90241-7

Cited by 65 publications

(15 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results were compared to control assays incubated without inhibitor. As in plant microsomes [31], a sig- The same fluorescent product, umbelliferone, is expected from coumarin hydroxylation or 7-alkoxycoumarin dealkylation. Results obtained by fluorimetry were confirmed by HPLC analysis, using the same column and gradient as in the assay of p-coumarate metabolisation.…”

Section: Enzyme Inactivation By Mechanism-based Inhibitorsmentioning

confidence: 90%

Catalytic Properties of the Plant Cytochrome P450 CYP73 Expressed in Yeast

Pierrel

Batard

Kazmaier³

et al. 1994

European Journal of Biochemistry

Self Cite

114

View full text Add to dashboard Cite

have been investigated. Microsomes from transformed yeast catalysed trans-cinnamate hydroxylation with high efficiency. CYP73 was highly specific for its natural substrate, and did not catalyse oxygenation of p-coumarate, benzoate, ferulate, naringenin or furanocoumarins. No metabolism of terpenoids or fatty acids, known substrates of plant P450s, was observed. CYP73 however demethylated the natural coumarin herniarin into umbelliferone. In addition, it was shown to oxygenate five xenobiotics and mechanism-based inactivators, including the herbicide chlorotoluron. All substrates of CYP73 were small planar aromatic molecules. Comparison of the kinetic parameters of CYP73 for its various substrates showed that, as expected, cinnamate was by far the best substrate of this P450. The physiological and toxicological significance of these observations are discussed.Cytochromes P450 form a large superfamily of several hundreds to several thousands of hemoproteins, involved in oxygen activation and oxygen tranfer into lipophilic molecules. They all share some sequence identity related to their common catalytic properties, i.e. heme and oxygen binding, electron transfer and oxygen activation [l]. Differences in their primary sequences usually reflect variations in specificity for substrates oxygenated. These differences may concern more than 80% of the amino acid sequence. However, the modification of a single amino acid residue can be sufficient to completely alter the substrate specificity of the enzyme 121.Full-length amino acid sequences presently available for plant P450s share less than 30% identity. This almost certainly implies great differences in the structures of their substrate binding sites. However, no relation between the structure of the enzymes and their catalytic activities has yet been established. CYP73 is the first DNA sequence coding for a plant P450 with an identified physiological function to have been isolated 131. It catalyses the 4-hydroxylation of trunscinnamic acid into p-coumaric acid. This hydroxylation is ductase (4-hydroxylating) (EC 1.14.13.11).the second reaction in the phenylpropanoid pathway. Cinnamate 4-hydroxylase (CA4H) is thus an obligatory step for the biosynthesis of lignin, a major component of the earth's total biomass. It is involved in the formation of most of the phenylpropanoid derivatives, essential for plant development, pigmentation and defense against both ultraviolet light and pathogens. Recent data [4-61 suggest that CA4H plays a central role in the regulation of the phenylpropanoid pathway. We, therefore, decided to establish more precisely which molecules are transformed by the enzyme or interfere with its catalytic activity. The determination of a population of substrates was also intended to provide information for analysis of the structurelfunction relationship of this plant P450. We devised an optimized system for the expression of CYP73 in Saccharomyces cerevisae [7]. This system provided yeast microsomes for which the only detectable P450 was CYP73. It routine...

show abstract

Section: Enzyme Inactivation By Mechanism-based Inhibitorsmentioning

confidence: 90%

Catalytic Properties of the Plant Cytochrome P450 CYP73 Expressed in Yeast

Pierrel

Batard

Kazmaier³

et al. 1994

European Journal of Biochemistry

Self Cite

114

View full text Add to dashboard Cite

show abstract

“…10 À4 M NDA is required for 50% inhibition of tabersonine 16-hydroxylase from Catharanthus roseus (StPierre and De Luca, 1995) and 10 À6 M can inhibit the (+)-abscisic acid 8'-hydroxylase from Zea mays (Krochko et al, 1998). C4H from Helianthus tuberosus is inhibited 50% by 10 À4 -5 · 10 À5 M ABT (Reichhart et al, 1982). Clot decreases tabersonine 16-hydroxylase activity from Catharanthus roseus (50% with 5 · 10 À5 M) (St-Pierre and De Luca, 1995).…”

Section: Dop6h From Cell Suspension Cultures Of L Albummentioning

confidence: 95%

Aryltetralin-lignan formation in two different cell suspension cultures of Linum album: Deoxypodophyllotoxin 6-hydroxylase, a key enzyme for the formation of 6-methoxypodophyllotoxin

2007

View full text Add to dashboard Cite

“…These values agreed with those of the in vitro metabolite (see above). To test for an involvement of the P450 monooxygenase system, phenobarbital, a known inducer of the P450 system (Reichhart et al, 1979), and ABT, a known inhibitor of this system (Reichhart et al, 1982;Cabanne et al, 1987;Moreland et al, 1996), were used. Upon inclusion of phenobarbital (0.6 mm), the original R F 0.27 metabolite, one new, more-polar metabolite, and three new, less-polar, unidentified metabolites were detected by TLC.…”

Section: In Vivo Metabolismmentioning

confidence: 99%

Cytochrome P450 Monooxygenases for Fatty Acids and Xenobiotics in Marine Macroalgae1

Pflugmacher

Sandermann

1998

Plant Physiology

View full text Add to dashboard Cite

The metabolism of xenobiotics has mainly been investigated in higher plant species. We studied them in various marine macroalgae of the phyla Chlorophyta, Chromophyta, and Rhodophyta. Microsomes contained high oxidative activities for known cytochrome (Cyt) P450 substrates (fatty acids, cinnamic acid, 3-and 4-chlorobiphenyl, 2,3-dichlorobiphenyl, and isoproturon; up to 54 pkat/mg protein). The presence of Cyt P450 (approximately 50 pmol/mg protein) in microsomes of the three algal families was demonstrated by CO-difference absorption spectra. Intact algal tissue converted 3-chlorobiphenyl to the same monohydroxymetabolite formed in vitro. This conversion was 5-fold stimulated upon addition of phenobarbital, and was abolished by the known P450 inhibitor, 1-aminobenzotriazole. It is concluded that marine macroalgae contain active species of Cyt P450 and could act as a metabolic sink for marine pollutants.

show abstract

Autocatalytic inactivation of plant cytochrome P-450 enzymes: Selective inactivation of cinnamic acid 4-hydroxylase from Helianthus tuberosus by 1-aminobenzotriazole

Cited by 65 publications

References 28 publications

Catalytic Properties of the Plant Cytochrome P450 CYP73 Expressed in Yeast

Catalytic Properties of the Plant Cytochrome P450 CYP73 Expressed in Yeast

Aryltetralin-lignan formation in two different cell suspension cultures of Linum album: Deoxypodophyllotoxin 6-hydroxylase, a key enzyme for the formation of 6-methoxypodophyllotoxin

Cytochrome P450 Monooxygenases for Fatty Acids and Xenobiotics in Marine Macroalgae1

Contact Info

Product

Resources

About