ハマグリのニコチン酸メチルトランスフェラーゼの精製と性質

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タイトル別名
  • Punfication and Properties of Nicotinate Methyltransferase from Marine Clam
  • ハマグリ ノ ニコチンサン メチルトランスフェラーゼ ノ セイセイ ト セイシ

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Nicotinate methyltransferase (EC 2.1.1.7) was purified from marine clam by ammonium sulfate fractionation (60-90% sat.) and aflinity chromatography (nicotinic acid coupled AH-Sepharose 4B column). The final enzyme preparation was not stable. Properties of the enzyme was investigated with a stable ammonium sulfate fraction of marine clam. Principal results obtained were as follows: optimum pH for the reaction, 6.0; stable pH range for storage, 6-8; Km value for nicotinic acid, 4.0 μM; Km value for S-adenosyl-L-methionine, 3.2 μM; optimum temperature for the reaction, 36℃; activation energy, 20,460 cal/mol; inhibitors, heavy metal ions, PCMB, picolinic acid and isonicotinic acid (competitive inhibitors, each Ki=0.1 mM), nicotinamide (noncompetitive inhibitor, Ki=8.6 mM, hence this enzyme preparation was clearly different from nicotinamide methyltransferase), trigonelline (product inhibition); reverse reaction, not detectable. Consequently, it was suggested that the biosynthesis of trigonelline in marine clam may be regulated by picolinic acid, nicotinamide, trigonelline concentration, etc.

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  • ビタミン

    ビタミン 61 (9), 445-450, 1987

    公益社団法人 日本ビタミン学会

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