Purification and characterization of a novel methyltransferase responsible for biosynthesis of halomethanes and methanethiol in Brassica oleracea

Jihad M. Attieh, Andrew D. Hanson, Hargurdeep S. Saini

Research output: Contribution to journalArticle

94 Citations (Scopus)

Abstract

A novel S-adenosyl-L-methionine:halide/bisulfide methyltransferase (EC 2.1.1.-) was purified approximately 1000-fold to apparent homogeneity from leaves of Brassica oleracea. The enzyme catalyzed the S-adenosyl-L- methionine-dependent methylation of the halides iodide, bromide, and chloride to monohalomethanes and of bisulfide to methanethiol. The dual function of the enzyme was demonstrated through co-purification of the halide- and bisulfide-methylating activities in the same ratio and by studies of competition between the alternative substrates iodide and bisulfide. The purification procedure included gel filtration, anion exchange chromatography, and affinity chromatography on adenosine-agarose. Elution of the protein from a chromatofocusing column indicated a pI value of 4.8. The pH optimum of halide methylation (5.5-7.0) was different from that of bisulfide methylation (7.0-8.0). The molecular mass values for the native and denatured protein were 29.5 and 28 kDa, respectively, suggesting that the active enzyme is a monomer. The enzyme had the highest specificity constant for iodide and the next highest for bisulfide. Substrate interaction kinetics and product inhibition patterns were consistent with an Ordered Bi Bi mechanism.

Original languageEnglish
Pages (from-to)9250-9257
Number of pages8
JournalJournal of Biological Chemistry
Volume270
Issue number16
DOIs
Publication statusPublished - 21 Apr 1995
Externally publishedYes

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Brassica
Biosynthesis
Methyltransferases
Methylation
Purification
Iodides
S-Adenosylmethionine
Enzymes
Affinity chromatography
Molecular mass
Substrates
Chromatography
Bromides
Affinity Chromatography
Adenosine
Sepharose
Gel Chromatography
Anions
Chlorides
Ion exchange

Cite this

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title = "Purification and characterization of a novel methyltransferase responsible for biosynthesis of halomethanes and methanethiol in Brassica oleracea",
abstract = "A novel S-adenosyl-L-methionine:halide/bisulfide methyltransferase (EC 2.1.1.-) was purified approximately 1000-fold to apparent homogeneity from leaves of Brassica oleracea. The enzyme catalyzed the S-adenosyl-L- methionine-dependent methylation of the halides iodide, bromide, and chloride to monohalomethanes and of bisulfide to methanethiol. The dual function of the enzyme was demonstrated through co-purification of the halide- and bisulfide-methylating activities in the same ratio and by studies of competition between the alternative substrates iodide and bisulfide. The purification procedure included gel filtration, anion exchange chromatography, and affinity chromatography on adenosine-agarose. Elution of the protein from a chromatofocusing column indicated a pI value of 4.8. The pH optimum of halide methylation (5.5-7.0) was different from that of bisulfide methylation (7.0-8.0). The molecular mass values for the native and denatured protein were 29.5 and 28 kDa, respectively, suggesting that the active enzyme is a monomer. The enzyme had the highest specificity constant for iodide and the next highest for bisulfide. Substrate interaction kinetics and product inhibition patterns were consistent with an Ordered Bi Bi mechanism.",
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Purification and characterization of a novel methyltransferase responsible for biosynthesis of halomethanes and methanethiol in Brassica oleracea. / Attieh, Jihad M.; Hanson, Andrew D.; Saini, Hargurdeep S.

In: Journal of Biological Chemistry, Vol. 270, No. 16, 21.04.1995, p. 9250-9257.

Research output: Contribution to journalArticle

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