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标题：Conformational Stabilization of Rat S-Adenosylmethionine Decarboxylase by Putrescine
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作者：Makiko Wada ; Akira Shirahata
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2010
卷号：33
期号：11
页码：1800-1805
DOI：10.1248/bpb.33.1800
出版社：The Pharmaceutical Society of Japan
摘要：The activity and processing of mammalian S -adenosylmethionine decarboxylase (AdoMetDC) is stimulated by putrescine. To obtain new insights into the mechanism through which putrescine stimulates AdoMetDC, we investigated conformational changes in rat prostate AdoMetDC in the presence or absence of putrescine. We examined the reactivity of purified rat prostate AdoMetDC to the SH-reagent iodoacetic acid (IAA) and its susceptibility to proteolysis in the presence or absence of putrescine using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The activity of AdoMetDC treated with IAA in the absence of putrescine was reduced, but about 80% of its activity remained after treatment with IAA in the presence of putrescine. In the presence of putrescine, IAA incorporation was 1.9 mol IAA/mol of AdoMetDC α-subunit, while there was no incorporation of IAA in the β-subunit of AdoMetDC. In the absence of putrescine, 5.0 mol of IAA/mol of α-subunit and 0.9 mol of IAA/mol of β-subunit were incorporated. Only Cys292 and Cys310 were carboxymethylated by IAA in the presence of putrescine. In contrast, in the absence of putrescine all cysteines were carboxymethylated by IAA. In addition, putrescine slowed the rate of AdoMetDC degradation by trypsin. These results demonstrate that the conformation of AdoMetDC purified from rat prostate is stabilized by putrescine.
关键词：S-adenosylmethionine decarboxylase;putrescine;conformational stabilization;matrix assisted laser desorption ionization time-of-flight mass spectrometry;SH-reagent