Abstract
Formyltetrahydrofolate synthetase (E. C. 6. 3. 4. 3) was found in fresh spinach leaves and purified about 60-fold by treatments of ammonium sulfate, protamine sulfate, dialysis, and DEAE-cellulose column chromatography. Some properties of the enzyme were investigated. Optimum pH was found to be 7.5, and optimum temperature was observed to be at 37°C. In the enzyme reaction, FAH4 and formate were required specifically as the substrates, and Mg++ and ATP were essential components. The Michaelis constants for dl-FAH4, formate, ATP and magnesium chloride were 1.7×10−3 m, 1.7×10−2 m, 4.1×10−4 m and 3.3×10−3 m, respectively. The primary product formed in the reaction catalyzed by the enzyme was suggested as N10-formyl-FAH4 spectrophotometrically. It was observed that the enzyme also catalyzed the reverse reaction. The possible role of the enzyme in plants was discussed.