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Algae 1999;14(3): 189-194. |
| Identification and Characterization of Nitrate Reductase in a Marine Dinoflagellate, Alexandrium tamarense
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| Kyoung-Jae Choi, Chi-Hun Ha, Myung-Soo Han, Joong-Kyun Jeon, Ki-Tae Kim, Hae-Ok Lee, Moon-Young Yoon
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Department of Chemistry and Department of Life Science, Hanyang University. Faculty of Marine Bioscience & Technology, Kangnung Nat. University. Seoulin Research Institute of Life Science, Seoulin Scientific Co., Ltd.
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| ABSTRACT |
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The Nitrate reductase (NR) from the toxic phytoplankton, Alexandrium tamarense, has been identified by the diazo coupling assay method that was based on the formation of a red azo compound. Addition of polyvinylpyrrolidone(PVP) to the extract buffer showed the highest NR activity. The crude extract of A. tamarense has an NR specific activity of 0.0027 U/mg, which is lower than the NR activities found for other algae. The optimum pH for enzymatic reaction was 8.0 and the optimum temperature for maximum activity was 25℃. The apparent Michaelis-Menten constants(K sub(m)) in the diazo coupling nitrate reductase assay are 63 μM for NADH and 14 μM for NO sub(3) super(-), respectively. The NR of A. tamarense was NADH specific, while NADPH also revealed small nitrate-reducing activity like most of the algae.
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| Key words:
Alexandrium tamarense, Characterization, dinoflagellate, identification, nitrate reductase |
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