Some characteristics of cotton pyrophosphatase activation by magnesium

The effect of Mg2+ ions on inducing pyrophosphatase activity of germinating cotton (Gossypium hirsutum L.) seeds was investigated. The presence of Mg2+ ions in the germination medium markedly shortened time for the attainment of the pyrophosphatase maximum activity (T max). In the absence of Mg2+ ions in the nutrient medium, T max comprised 6.0–6.5 days, whereas in the presence of 3–5 mM Mg2+, T max was decreased to 3–4 days. An increase in the concentration of Mg2+ ions in the medium up to 5 mM resulted in an increase in pyrophosphatase activity. The effect of Mg2+ ions on the activity of a purified pyrophosphatase preparation isolated from three-day-old cotton seedlings was investigated. Mg2+ ions did not affect the rate of attainment of a maximum pyrophosphatase activity, but decreased the value of the Michaelis-Menten constant.

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