Biosynthesis of trigonelline from nicotinate mononucleotide in mungbean seedlings |
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Authors: | Zheng Xin-Qiang Matsui Ayu Ashihara Hiroshi |
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Affiliation: | Department of Biological Sciences, Graduate School of Humanities and Sciences, Ochanomizu University, Bunkyo-ku, Tokyo 112-8610, Japan. |
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Abstract: | To determine the biosynthetic pathway to trigonelline, the metabolism of [carboxyl-(14)C]nicotinate mononucleotide (NaMN) and [carboxyl-(14)C]nicotinate riboside (NaR) in protein extracts and tissues of embryonic axes from germinating mungbeans (Phaseolus aureus) was investigated. In crude cell-free protein extracts, in the presence of S-adenosyl-L-methionine, radioactivity from [(14)C]NaMN was incorporated into NaR, nicotinate and trigonelline. Activities of NaMN nucleotidase, NaR nucleosidase and trigonelline synthase were also observed in the extracts. Exogenously supplied [(14)C]NaR, taken up by embryonic axes segments, was readily converted to nicotinate and trigonelline. It is concluded that the NaMN-->NaR-->nicotinate-->trigonelline pathway is operative in the embryonic axes of mungbean seedlings. This result suggests that trigonelline is synthesised not only from NAD but also via the de novo biosynthetic pathway of pyridine nucleotides. |
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Keywords: | IMP, inosine-5′-mononucleotide NaAD, nicotinate adenine nucleotide NaMN, nicotinate mononucleotide NaR, nicotinate riboside NMN, nicotinamide mononucleotide NR, nicotinamide riboside PPi, pyrophosphate PRPP, 5-phosphoribosyl-1-pyrophosphate |
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