Variable Nornicotine Enantiomeric Composition Caused by Nicotine Demethylase CYP82E4 in Tobacco Leaf
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- 作者：Bin Cai ; Lowell P. Bush
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2012
- 出版时间：November 21, 2012
- 年：2012
- 卷：60
- 期：46
- 页码：11586-11591
- 全文大小：345K
- 年卷期：v.60,no.46(November 21, 2012)
- ISSN：1520-5118
文摘
Nornicotine is the demethylation product of nicotine and the precursor of tobacco-specific nitrosamine N鈥?/i>-nitrosonornicotine (NNN) in tobacco (Nicotiana tabacum L.). There is an inconsistent enantiomer fraction (EF) of nornicotine reported in the literature. The objective of this study was to explore possible mechanisms to account for the variable EFnnic in tobacco. A survey of tobacco with different demethylating capabilities confirmed that there was variable EFnnic. Experiments of induction and inhibition of the major nicotine demethylase CYP82E4 activity in tobacco demonstrated that CYP82E4 selectively demethylated (S)-nicotine and resulted in different EFnnic in tobacco leaves. Results from plants with silenced demethylases by RNAi suggested that other demethylases selectively used (R)-nicotine and resulted in high EFnnic. In summary, enantioselective demethylation likely plays an important role in contributing to a large and variable EFnnic observed in tobacco.