纤细裸藻中6-磷酸果糖-2-激酶和果糖-2,6-二磷酸酶的发生与特性

Occurrence and characterization of fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase in Euglena gracilis.

Enomoto T, Kakihara K, Miyatake K, Kitaoka S

Department of Agricultural Chemistry, University of Osaka Prefecture, Japan.

Comp Biochem Physiol B. 1989;92(3):477-80. doi: 10.1016/0305-0491(89)90119-3.

Abstract

Fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase occurred in Euglena gracilis SM-ZK, and is located in cytosol. 2. Fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase were partially purified, and both enzyme activities were not separated during the partial purification. 3. The pH optimum for fructose 6-phosphate, 2-kinase activity was 7.0. The saturation curve of the enzyme activity for ATP concentration was hyperbolic, and the Km value for the substrate was 0.88 mM. On the other hand, the saturation curve of the enzyme activity for fructose 6-phosphate concentration was sigmoidal, and the K0.5 value for the substrate was 70 microM. 4. The pH optimum for fructose 2,6-bisphosphatase activity was 6.5. The saturation curve for fructose 2,6-bisphosphate concentration was sigmoidal, and the K0.5 value for the substrate was 1.29 microM. Fructose 2,6-bisphosphate showed a substrate inhibition at high concentration over 5 microM, and the enzyme activity was completely inhibited by 20 microM of fructose 2,6-bisphosphate.

摘要

6-磷酸果糖-2-激酶和果糖-2,6-二磷酸酶存在于纤细裸藻SM-ZK中，且位于胞质溶胶中。2. 6-磷酸果糖-2-激酶和果糖-2,6-二磷酸酶被部分纯化，且在部分纯化过程中两种酶活性未被分离。3. 6-磷酸果糖-2-激酶活性的最适pH为7.0。该酶活性对ATP浓度的饱和曲线呈双曲线，底物的Km值为0.88 mM。另一方面，该酶活性对6-磷酸果糖浓度的饱和曲线呈S形，底物的K0.5值为70 μM。4. 果糖-2,6-二磷酸酶活性的最适pH为6.5。果糖-2,6-二磷酸浓度的饱和曲线呈S形，底物的K0.5值为1.29 μM。果糖-2,6-二磷酸在浓度高于5 μM时表现出底物抑制作用，且20 μM的果糖-2,6-二磷酸可完全抑制该酶活性。