- Large-scale, protection-free synthesis of Se-adenosyl-l-selenomethionine analogues and their application as cofactor surrogates of methyltransferases
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S-Adenosyl-l-methionine (SAM) analogues have previously demonstrated their utility as chemical reporters of methyltransferases. Here we describe the facile, large-scale synthesis of Se-alkyl Se-adenosyl-l-selenomethionine (SeAM) analogues and their precursor, Se-adenosyl-l-selenohomocysteine (SeAH). Comparison of SeAM analogues with their equivalent SAM analogues suggests that sulfonium-to-selenonium substitution can enhance their compatibility with certain protein methyltransferases, favoring otherwise less reactive SAM analogues. Ready access to SeAH therefore enables further application of SeAM analogues as chemical reporters of diverse methyltransferases.
- Bothwell, Ian R.,Luo, Minkui
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supporting information
p. 3056 - 3059
(2014/06/23)
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- SOYBEANS AND RADISH LEAVES CONTAIN ONLY ONE OF THE SULFONIUM DIASTEREOISOMERS OF S-ADENOSYLMETHIONINE
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Glycine max; Leguminosae; soybean; S-adenosylmethionine; S-adenosylethionine; sulfonium diastereoisomers; liquid chromatography.Using a liquid chromatography method that separates the two sulfonium diastereoisomers of adenosylmethionine, we have found that immature soybeans, soybean callus culture, radish leaves, yeast and rat liver contain only the (S)-sulfonium form of S-adenosylmethionine.Our findings contradict the suggestion by Stolowitz and Minch that 10-20percent of naturally-occurring adenosylmethionine may have the (R)-configuration at the sulfonium pole.Absence of the (R)-sulfonium isomer of adenosylmethionine in biological materials indicates that the (R)-sulfonium form of adenosylmethionine present in commercial adenosylmethionine samples is an artifact of the isolation procedure.Our method of measuring the isomers of adenosylmethionine enabled us to readily determine the rate of racemization and hydrolysis of adenosylmethionine.Our rate constants for racemization (Kr) and hydrolysis (Kh) were 2.4x10-6 sec-1 and 12.3x10-6 sec-1, respectively; values which are noticeably different from those of Wu and coworkers which were obtained with a more complicated method (Kr=8x10-6 sec-1; Kh=6x10-6 sec-1).We believe the absence of the (R)-isomer in vivo is best explained by stabilization of the (S)-isomer as suggested by Wu et al.Although the tissues we have analysed contained the (S)-sulfonium form of adenosylmethionine exclusively, when ethionine-resistant soybean cell lines were given ethionine, they accumulated both sulfonium diastereoisomers of adenosylethionine.
- Creason, Gary L.,Madison, James T.,Thompson, John F.
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p. 1151 - 1156
(2007/10/02)
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