1. Biosynthetic origin of the nitrogen atom in cyanamide in Vicia villosa subsp. varia.
- Author
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KAMO, Tsunashi, KATO, Kenji, ABE, Shun, HIROTA, Mitsuru, YAMAYA, Hiroko, HIRADATE, Syuntaro, and FUJII, Yoshiharu
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CALCIUM cyanamide ,CYANIDES ,CALCIUM compounds ,LEGUMES ,BIOSYNTHESIS ,AMMONIUM ,PLANT shoots ,ARGININE ,UREA - Abstract
Natural cyanamide (NH
2 CN) has recently been found in three Leguminosae plants: Vicia villosa subsp. varia, Vicia cracca and Robinia pseudo-acacia. As cyanamide has long been thought to be absent in nature, its physiological role and biosynthesis are totally unknown. In the present study, we demonstrated the incorporation of15 N from [15 N]nitrate and [15 N]ammonium into cyanamide using shoots of V. villosa subsp. varia, which ruled out the possibility that nodules are essential in cyanamide biosynthesis. We also applied [15 N2 ]cyanamide to shoots of V. villosa subsp. varia to monitor its turnover, and detected [15 N2 ]cyanamide in the leaves within 4 h; it was present without detectable degradation for more than 4 days. In contrast, maximum incorporation of15 N into cyanamide molecules was observed after 4 days of feeding the shoots with15 N-labeled inorganic ions andl-[amide-15 N]-glutamine, indicating that these nitrogenous compounds are distant precursors of cyanamide. Although the guanidino group ofl-arginine (-NH-C(NH2 )=NH) and urea (NH2 C(=O)NH2 ) were candidate precursors of cyanamide on the basis of structural similarity, direct incorporation of the guanidino group ofl-[13 C6 ,15 N4 ]-arginine and [13 C,15 N2 ]urea into cyanamide was not observed. These results eliminated the possibility that cyanamide is biosynthesized by the addition of ammonia to an electrophilic carbon or by the conversion of the tested compounds that were structurally relevant to cyanamide. [ABSTRACT FROM AUTHOR]- Published
- 2009
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