Inactivation of 3-(3,4-dihydroxyphenyl)alanine decarboxylase by 2-(fluoromethyl)-3-(3,4-dihydroxyphenyl)alanine

Al, Maycock; Sd, Aster; Aa, Patchett

doi:10.1021/bi00545a016

Cited by 57 publications

(25 citation statements)

References 47 publications

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“…TDC from certain plants has been shown to be strongly inhibited by a-fluoromethyl-3,4-dihydroxyphenylalanine (a suicide inactivator [12]) and by the phenylalanine analog AOPP (2). Eschscholtzia TDC was largely unaffected by preincubation with a-fluoromethyl(3,4-dihydroxyphenyl)-alanine and difluoromethyl-tyrosine (Table IV) but was inactivated by AOPP (Table IV; Fig.…”

Section: Resultsmentioning

confidence: 99%

Elicitor-Induced l-Tyrosine Decarboxylase from Plant Cell Suspension Cultures

Marques¹,

Brodelius²

1988

Plant Physiol.

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Properties of purified L-tyrosine decarboxylase (EC 4.1.1.25) from elicitor-induced cell suspension cultures of Eschscholtzia californica Cham. and Thalictrum rugosum Ait. are described. L-Tyrosine decarboxylase is a dimeric enzyme with a molecular weight of 112,600 ± 600 daltons. The isoelectric point was estimated to be at pH 5.2 and pH 5.4for the enzyme from E. californica and T. rugosum, respectively. The purified enzymes were stabilized in the presence of pyridoxal-5-phosphate. Optimum pH for the enzyme from both plants was found to be 8.4. Enzyme activity was dependent on exogeneously supplied pyridoxal-5-phosphate. The enzyme decarboxylated L-tyrosine and L-,a-3,4-dihydroxyphenylalanine but was inactive toward L-phenylalanine and Ltryptophan. Apparent Km values of Eschscholtzia-and Thalictrum-decarboxylase for L-tyrosine were 0.25 ± 0.03 and 0.27 ± 0.04 millimolar, respectively. Similar affinities were found for L-3,4-dihydroxyphenylalanine. Eschscholtzia L-tyrosine decarboxylase was strongly inhibited by the phenylalanine analogue L-a-aminooxy-#-phenylpropionate and largely unaffected by D,L-a-monofluoromethyl-3,4-dihydroxyphenylalanine and a-difluoromethyltyrosine.An enhanced biosynthesis of berberine in cell suspension cultures of Thalictrum rugosum Ait. was achieved by treating the cells with a yeast carbohydrate elicitor (6). This increased product formation followed an increase of TDC2 (EC 4.1.1.25) activity (8). These findings, coupled with results from feeding experiments with radioactive labeled tyrosine (8), indicate that TDC might control the branching point between primary and secondary metabolisms. Furthermore, the synthesis ofdopamine (one of the direct precursors of norlaudanosoline) from tyrosine during the initial steps of alkaloid biosynthesis is not clear. Two possible routes could be considered: first, hydroxylation of tyrosine to DOPA followed by a decarboxylation of DOPA to dopamine; second, decarboxylation of tyrosine to tyramine and subsequent hydroxylation of tyramine to dopamine.Data about the catalytic and molecular properties of plant DOPA and tyrosine decarboxylase would be valuable in establishing the function of these enzymes in alkaloid biosynthesis. However, only very limited information about these enzymes has been published (2,7,9,14,15 A sample (0.5 ml) ofpurified TDC was desalted by centrifugation through a 5 ml Sephadex G-25 column equilibrated in 25 mM bis-Tris-HCI (pH 6.7) and applied to the Mono P column, which had been equilibrated with the same buffer. Elution was performed with a decreasing pH gradient (30 ml) using a 10-fold diluted Polybuffer 74-HCI (pH 4.9). The pI values were also estimated by isoelectric focusing. IEF was carried out on tubes as described (5) using ampholine pH 4 to 6. 52 www.plantphysiol.org on May 11, 2018 -Published by Downloaded from

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Section: Resultsmentioning

confidence: 99%

Elicitor-Induced l-Tyrosine Decarboxylase from Plant Cell Suspension Cultures

Marques¹,

Brodelius²

1988

Plant Physiol.

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“…We also demonstrated that in situ accumulation of radioactivity was dependent on tissue activity of AADC. Previous studies reported that incubation of [ 3 H 2 ]-MFMT with purified AADC resulted in the formation of a stable complex [ 3 H]-MFM-dopa/AADC (Maycock et al, 1980). Pretreatment of rats with MFM-dopa resulted in almost complete inhibition of in vitro activity of AADC (Jung et al, 1984).…”

Section: Discussionmentioning

confidence: 95%

“…This methodology is based on the potential in vivo TH-catalyzed transformation of (3Ј,5Ј)- (Maycock et al, 1980). Our previous study suggested that incorporation of [ 3 H 2 ]-MFMT in brain protein metabolism was insignificant and that the in vivo metabolite of [ 3 H 2 ]-MFMT via TH activity was, as expected from previous pharmacological results, a potent and irreversible substrate for AADC (Lafargue et al, 1994).…”

Section: Introductionmentioning

confidence: 90%

In situ examination of tyrosine hydroxylase activity in the rat locus coeruleus using (3?,5?)-[3H2]-?-fluoromethyl-tyrosine as substrate of the enzyme

Bezin

Marcel

Garcia

et al. 2000

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Tyrosine hydroxylase (TH) activity can be modified by changes in the specific activity of the enzyme (SA(TH)) or in the levels of active enzyme. We developed a methodology making it possible to measure with excellent anatomical resolution TH enzymatic activity and TH protein quantity by quantitative autoradiography and immunoautoradiography, respectively, from adjacent sections taken at serial intervals along the longitudinal extent of a same brain. SA(TH) was estimated by the slope of linear regressions established between TH activity and TH quantity measured at each anatomical plane. To evaluate TH activity, we used (3',5')-[(3)H(2)]-(D, L)-alpha-fluoromethyl-tyrosine [(3)H(2)]-MFMT, which is transformed by TH to [(3)H]-MFM-dopa, a potent and irreversible substrate for aromatic amino acid decarboxylase. We found that the SA(TH) in the cell body area of the LC (PKA) was 48% lower than that evaluated in the surrounding pericoerulean neuropil (PCN). In the PCN, 22% only of TH level exhibited a level of enzymatic activity above threshold. We also examined how SA(TH) was distributed in the LC 15 min and 3 days after RU 24722 treatment, a potent phasic and tonic activator of TH enzyme in noradrenergic neurons. Two distinct mechanisms have been observed: the short-term effect was due to an increase in the SA(TH) in the PKA only, while the long-term effect was mainly caused by an increase in the number of active TH proteins in the PCN. These results suggest that the fine regulation of TH activity which occurs in the different compartments of LC neurons may be critical in the functions involving the LC.

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“…which kills itself after the release of a stoichiometric amount of C 0 2 and F-, consistent with a decarboxylative elimination sequence and then an efficient eneamino-PLP capture by a suicidal enzymic nucleophile (95). The pharmacological consequences of such specific inactivation of these key decarboxylases are being hotly pursued (e.g., 1 1,96,97).…”

Section: Christopher Walshmentioning

confidence: 88%

Fluorinated Substrate Analogs: Routes of Metabolism and Selective Toxicity

Walsh

1983

Advances in Enzymology - And Related Areas of Molecular Biology

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Inactivation of 3-(3,4-dihydroxyphenyl)alanine decarboxylase by 2-(fluoromethyl)-3-(3,4-dihydroxyphenyl)alanine

Cited by 57 publications

References 47 publications

Elicitor-Induced l-Tyrosine Decarboxylase from Plant Cell Suspension Cultures

Elicitor-Induced l-Tyrosine Decarboxylase from Plant Cell Suspension Cultures

In situ examination of tyrosine hydroxylase activity in the rat locus coeruleus using (3?,5?)-[3H2]-?-fluoromethyl-tyrosine as substrate of the enzyme

Fluorinated Substrate Analogs: Routes of Metabolism and Selective Toxicity

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