Properties of 1-phosphofructokinase from Pseudomonas piutida

Abstract

The 1-phosphofructokinase (1-PFK, EC 2.7.1.56) from Pseudomonas putida was partially purified by a combination of (NH4)2SO4 fractionation and DEAE-Sephadex column chromatography. In its kinetic properties, this enzyme resembled the 1-PFK's from other bacteria. With the substrates fructose-1-phosphate (F-1-P) and adenosine triphosphate (ATP) Michaelis–Menten kinetics were observed, the Km for one substrate being unaffected by a variation in the concentration of the other substrate. At pH 8.0, the Km values for F-1-P and ATP were 1.64 × 10−4 M and 4.08 × 10−4 M, respectively. At fixed concentrations of F-1-P and ATP, an increase in the Mg2+ resulted in sigmoidal kinetics. Activity was inhibited by ATP when the ratio of ATP:Mg2+ was greater than 0.5 suggesting that ATP:2 Mg2+ was the substrate and free ATP was inhibitory. Activity of 1-PFK was stimulated by K+ and to a lesser extent by NH4+ and Na+. The reaction rate was unaffected by 2 mM K2HPO4, pyruvate, phosphoenolpyruvate, adenosine monophosphate, adenosine 3′,5′-cyclic monophosphate, fructose-6-phosphate, glucose-6-phosphate, 6-phosphogluconate, 2-keto-3-deoxy-6-phosphogluconate, or citrate. The results indicated that the 1-PFK from P. putida was not allosterically regulated by a number of metabolites which may play an important role in the catabolism of D-fructose.