Characterization of adducts formed in the reaction of 2-chloro-4- methylthiobutanoic acid with 2′-deoxyguanosine

Sachiko Kimura, Miki Nakayama, Tsutomu Hatano, Ayako Segawa, Toshiaki Watanabe, Hikoya Hayatsu, Sakae Arimoto

Research output: Contribution to journalArticle

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Abstract

2-Chloro-4-methylthiobutanoic acid (CMBA) is a direct-acting mutagen found in salt-nitrite-treated Sanma fish or similarly treated methionine solution. In this study, CMBA was reacted with 2′-deoxyguanosine (dG) in phosphate buffer (pH 7.4) at 37 °C. The HPLC-UV analysis showed that two products were mainly formed during the reaction. These were isolated, purified by semipreparative HPLC, and characterized as N7-guanine adducts: N7-(3-carboxy-3-methylthiopropyl)guanine (A1) and N7-(1-carboxy-3- methylthiopropyl)guanine (A2). Furthermore, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) analysis was employed to investigate the possible formation of minor products during the time-course of the reaction of CMBA with dG. It was found that N7-dG adducts, the precursors of A1 and A2, were formed early in the reaction and that subsequently the spontaneous depurination occurred to yield stable N7-guanine adducts A1 and A2. Stability studies in phosphate buffer (pH 7.4) at 37 °C showed that the amount of each N7-dG adduct decreased rapidly with a half-life of 6 h and 4 h to yield A1/A2, respectively. A regioisomer of N7-dG adducts was also observed in the LC/ESI-MS/MS analysis, but it was not characterized in detail because it was present only in trace amounts. On the basis of structural features, A1 and A2 seemed to be formed from the reaction of dG with 1-methyl-2-thietaniumcarboxylic acid, an intermediate resulting from the cyclization of CMBA. However, A2 might also have formed from the direct reaction of dG and CMBA. N7-Alkylation of the guanine residue and subsequent depurination are known to produce apurinic sites in DNA that induce point mutations and may be responsible for the observed CMBA-induced mutagenesis.

Original languageEnglish
Pages (from-to)1755-1761
Number of pages7
JournalChemical Research in Toxicology
Volume18
Issue number11
DOIs
Publication statusPublished - Nov 2005

Fingerprint

Deoxyguanosine
varespladib methyl
Guanine
Deoxyguanine Nucleotides
Buffers
High Pressure Liquid Chromatography
Phosphates
Electrospray Ionization Mass Spectrometry
Mutagens
Alkylation
Electrospray ionization
Mutagenesis
Cyclization
Nitrites
Tandem Mass Spectrometry
Point Mutation
Liquid Chromatography
Liquid chromatography
Methionine
Half-Life

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Characterization of adducts formed in the reaction of 2-chloro-4- methylthiobutanoic acid with 2′-deoxyguanosine. / Kimura, Sachiko; Nakayama, Miki; Hatano, Tsutomu; Segawa, Ayako; Watanabe, Toshiaki; Hayatsu, Hikoya; Arimoto, Sakae.

In: Chemical Research in Toxicology, Vol. 18, No. 11, 11.2005, p. 1755-1761.

Research output: Contribution to journalArticle

Kimura, Sachiko ; Nakayama, Miki ; Hatano, Tsutomu ; Segawa, Ayako ; Watanabe, Toshiaki ; Hayatsu, Hikoya ; Arimoto, Sakae. / Characterization of adducts formed in the reaction of 2-chloro-4- methylthiobutanoic acid with 2′-deoxyguanosine. In: Chemical Research in Toxicology. 2005 ; Vol. 18, No. 11. pp. 1755-1761.
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abstract = "2-Chloro-4-methylthiobutanoic acid (CMBA) is a direct-acting mutagen found in salt-nitrite-treated Sanma fish or similarly treated methionine solution. In this study, CMBA was reacted with 2′-deoxyguanosine (dG) in phosphate buffer (pH 7.4) at 37 °C. The HPLC-UV analysis showed that two products were mainly formed during the reaction. These were isolated, purified by semipreparative HPLC, and characterized as N7-guanine adducts: N7-(3-carboxy-3-methylthiopropyl)guanine (A1) and N7-(1-carboxy-3- methylthiopropyl)guanine (A2). Furthermore, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) analysis was employed to investigate the possible formation of minor products during the time-course of the reaction of CMBA with dG. It was found that N7-dG adducts, the precursors of A1 and A2, were formed early in the reaction and that subsequently the spontaneous depurination occurred to yield stable N7-guanine adducts A1 and A2. Stability studies in phosphate buffer (pH 7.4) at 37 °C showed that the amount of each N7-dG adduct decreased rapidly with a half-life of 6 h and 4 h to yield A1/A2, respectively. A regioisomer of N7-dG adducts was also observed in the LC/ESI-MS/MS analysis, but it was not characterized in detail because it was present only in trace amounts. On the basis of structural features, A1 and A2 seemed to be formed from the reaction of dG with 1-methyl-2-thietaniumcarboxylic acid, an intermediate resulting from the cyclization of CMBA. However, A2 might also have formed from the direct reaction of dG and CMBA. N7-Alkylation of the guanine residue and subsequent depurination are known to produce apurinic sites in DNA that induce point mutations and may be responsible for the observed CMBA-induced mutagenesis.",
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AU - Kimura, Sachiko

AU - Nakayama, Miki

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AU - Segawa, Ayako

AU - Watanabe, Toshiaki

AU - Hayatsu, Hikoya

AU - Arimoto, Sakae

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N2 - 2-Chloro-4-methylthiobutanoic acid (CMBA) is a direct-acting mutagen found in salt-nitrite-treated Sanma fish or similarly treated methionine solution. In this study, CMBA was reacted with 2′-deoxyguanosine (dG) in phosphate buffer (pH 7.4) at 37 °C. The HPLC-UV analysis showed that two products were mainly formed during the reaction. These were isolated, purified by semipreparative HPLC, and characterized as N7-guanine adducts: N7-(3-carboxy-3-methylthiopropyl)guanine (A1) and N7-(1-carboxy-3- methylthiopropyl)guanine (A2). Furthermore, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) analysis was employed to investigate the possible formation of minor products during the time-course of the reaction of CMBA with dG. It was found that N7-dG adducts, the precursors of A1 and A2, were formed early in the reaction and that subsequently the spontaneous depurination occurred to yield stable N7-guanine adducts A1 and A2. Stability studies in phosphate buffer (pH 7.4) at 37 °C showed that the amount of each N7-dG adduct decreased rapidly with a half-life of 6 h and 4 h to yield A1/A2, respectively. A regioisomer of N7-dG adducts was also observed in the LC/ESI-MS/MS analysis, but it was not characterized in detail because it was present only in trace amounts. On the basis of structural features, A1 and A2 seemed to be formed from the reaction of dG with 1-methyl-2-thietaniumcarboxylic acid, an intermediate resulting from the cyclization of CMBA. However, A2 might also have formed from the direct reaction of dG and CMBA. N7-Alkylation of the guanine residue and subsequent depurination are known to produce apurinic sites in DNA that induce point mutations and may be responsible for the observed CMBA-induced mutagenesis.

AB - 2-Chloro-4-methylthiobutanoic acid (CMBA) is a direct-acting mutagen found in salt-nitrite-treated Sanma fish or similarly treated methionine solution. In this study, CMBA was reacted with 2′-deoxyguanosine (dG) in phosphate buffer (pH 7.4) at 37 °C. The HPLC-UV analysis showed that two products were mainly formed during the reaction. These were isolated, purified by semipreparative HPLC, and characterized as N7-guanine adducts: N7-(3-carboxy-3-methylthiopropyl)guanine (A1) and N7-(1-carboxy-3- methylthiopropyl)guanine (A2). Furthermore, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) analysis was employed to investigate the possible formation of minor products during the time-course of the reaction of CMBA with dG. It was found that N7-dG adducts, the precursors of A1 and A2, were formed early in the reaction and that subsequently the spontaneous depurination occurred to yield stable N7-guanine adducts A1 and A2. Stability studies in phosphate buffer (pH 7.4) at 37 °C showed that the amount of each N7-dG adduct decreased rapidly with a half-life of 6 h and 4 h to yield A1/A2, respectively. A regioisomer of N7-dG adducts was also observed in the LC/ESI-MS/MS analysis, but it was not characterized in detail because it was present only in trace amounts. On the basis of structural features, A1 and A2 seemed to be formed from the reaction of dG with 1-methyl-2-thietaniumcarboxylic acid, an intermediate resulting from the cyclization of CMBA. However, A2 might also have formed from the direct reaction of dG and CMBA. N7-Alkylation of the guanine residue and subsequent depurination are known to produce apurinic sites in DNA that induce point mutations and may be responsible for the observed CMBA-induced mutagenesis.

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