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KMID : 0368419970400020080
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Journal of Plant Biology
1997 Volume.40 No. 2 p.80 ~ p.88
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Biochemical Characteristics of S-adenosylmethionine Decarboxylase from Garnation(Dianthus caryophyllus L.) Petals
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Lee, Myeong Min
Nam, Kyoung Hee/Lee, Eun Kyoung/Lee, Sun Hi/Lee, Ky Young
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Abstract
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We have partially purified S-adenosylmethionine decarboxylase (EC 4.1.1.50, SAMDC) from carnation (Dianthus caryophyllus L.) petals and generated polyclonal antibodies against CSDC 16 protein (Lee et al., 1996) overexpressed in E. coli. The protein has been purified approximately 126.8 fold through the steps involving ammonium sulfate fractionation, DEAE-Sepharose column chromatography and Sephacryl S-300 gel filtration. Its molecular mass was 42 kDa in native form and we could also detect a band of 32 kDa molecular mass on SDS-PAGE in western blot analysis using the polyclonal antibodies. The Km value of this enzyme for S-adenosylmethionine was 26.3 μM. The optimum temperature and pH for S-adenosylmethionine decarboxylase activity were 35℃ and pH 8.0, respectively. Putrescine and Mg^(2+) had no effects on the activation of the enzyme activity. Mg^(2+) did not have any significant effects on the enzyme activity. SAMDC activity was inhibited by putrescine, spermidine and spermine. Methylglyoxal bis-(guanylhydrazone) (MGBG), carbonyl reagents such as hydroxylamine and phenylhydrazine, and sulfhydryl reagent such as 5,5´-dithio-bis (2-nitrobenzoic acid) (DTNB) were effective inhibitors of the enzyme. However, isonicotinic acid hydrazide known as an inhibitor of 5´-pyridoxal phosphate (PLP) dependent enzyme activity had no significant effect on the enzyme activity. These results and our previously reported results (Lee et al., 1997b) suggest that S-adenosylmethionine decarboxylase is a heterodimer αβ, and some carbonyl group and sulfhydryl group are involved in the catalytic activity.
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