A chemical model of catechol-O-methyltransferase. Methylation of 3,4- dihydroxybenzaldehyde in methanol solution

S. Sugata

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Abstract

The reaction of 3,4-dihydroxybenzaldehyde (LH2) and dimethyl sulfate (DMS) in forming m- and p-O-methylated products (vanillin and isovanillin, respectively) in a methanol buffer solution was studied kinetically as a chemical model of catechol-O-methyltransferase (COMT). The O-methylations, especially m-O-methylations, were catalyzed by divalent metal ions such as Cu(II), Mg(II) and Zn(II). A clear Mg(II) catalysis was observed for the first time in this medium. As Mg(II) is an important metal in the COMT catalyzed reaction in vivo, this observation is very interesting. Kinetic analyses of the present data and recalculation of a part of the previous data offered the following evidence. In Cu(II) catalysis, a 1:2 complex(CuL2) was more active than the 1:1 complex (CuL). On the other hand, in Mg(II) catalysis and Zn(II) catalysis, ML was more active than ML2. These facts show that ML2 is not always more active than ML, contrary to previous reports. Methanolysis of DMS, a significant side reaction of this model reaction, and dissociation of LH2 were studied thoroughly as bases for these kinetic analyses.

Original languageEnglish
Pages (from-to)1007-1011
Number of pages5
JournalChemical and Pharmaceutical Bulletin
Volume41
Issue number6
Publication statusPublished - 1993

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Chemical Models
Catechol O-Methyltransferase
Methylation
Catalysis
Methanol
Metals
Kinetics
Metal ions
Buffers
Ions
protocatechualdehyde
dimethyl sulfate

ASJC Scopus subject areas

  • Chemistry(all)
  • Organic Chemistry
  • Drug Discovery
  • Pharmacology

Cite this

A chemical model of catechol-O-methyltransferase. Methylation of 3,4- dihydroxybenzaldehyde in methanol solution. / Sugata, S.

In: Chemical and Pharmaceutical Bulletin, Vol. 41, No. 6, 1993, p. 1007-1011.

Research output: Contribution to journalArticle

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AB - The reaction of 3,4-dihydroxybenzaldehyde (LH2) and dimethyl sulfate (DMS) in forming m- and p-O-methylated products (vanillin and isovanillin, respectively) in a methanol buffer solution was studied kinetically as a chemical model of catechol-O-methyltransferase (COMT). The O-methylations, especially m-O-methylations, were catalyzed by divalent metal ions such as Cu(II), Mg(II) and Zn(II). A clear Mg(II) catalysis was observed for the first time in this medium. As Mg(II) is an important metal in the COMT catalyzed reaction in vivo, this observation is very interesting. Kinetic analyses of the present data and recalculation of a part of the previous data offered the following evidence. In Cu(II) catalysis, a 1:2 complex(CuL2) was more active than the 1:1 complex (CuL). On the other hand, in Mg(II) catalysis and Zn(II) catalysis, ML was more active than ML2. These facts show that ML2 is not always more active than ML, contrary to previous reports. Methanolysis of DMS, a significant side reaction of this model reaction, and dissociation of LH2 were studied thoroughly as bases for these kinetic analyses.

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