精製ニコチンアミドメチルトランスフェラーゼを用いたS-アデノシル-_L-メチオニンの酵素的定量法の基礎的研究

概要

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Nicotinamide methyltransferase (EC 1.1.1.1) was purified from rat liver. The purification was conducted by ammonium sulfate fractionation and column chromatographies on DE 52, Butyl Toyopearl and Sephadex G-100. As the results, the enzyme was purified up to 254-fold with a yield of 11 %. The enzyme of Butyl Toyopearl fraction is stable, so this enzyme preparation was used for the determination of S-adenosyl-L-methionine (SAM). The enzymatic properites of the preparation were as follows : optimum temperature, 34.7℃; optimum pH, 5.9; K_m values for nicotinamide and SAM, 61.7 μM and 10.6 μM, respectively ; inhibitors, isonicotinamide, picolinamide, benzamide, 3-aminopyridine, salicylamide (all were competitive to nicotinamide), N^1-methyl-nicotinamide, S-adenosyl-L-homocysteine (product inhibition was observed with both substrates), PCMB, heavy metal ions, etc. The regression line for the determination of SAM with the enzyme reaction was linear until 600 pmol with a correlation coefficient of 0.998. The SAM contents in various samples were determined with this method. The high contents were observed in Lactobacillus plantarum, Escherichia coli, baker's yeast, tomato, etc. The possibility for the determination of SAM by this method in various samples was suggested.
日本ビタミン学会の論文
1990-12-25