Fructo kinase

The (ATPase)/(kinase) ratio was higher for unlabeled 2,5-anhydromannose than for the deuterated compound by a factor of 1.22, while for the two compounds as substrates for fructo-kinase (ADP production followed) the V/K isotope effect was 1.04 0.02, and there was no V isotope effect. If only the free aldehyde is an activator for the ATPase activity, while the free aldehyde and the hydrate have equal V/K values for the kinase reaction, the predicted isotope effect on the (ATPase)/ (kinase) ratio is 1.19, while that on the V/K for ADP production is 1.024. Thus, the aldehyde is the activator for fructo-kinase as well as for phosphofructokinase. 

Pearce, A.K., Booth, I.R., and Brown, A.J. 2001. Genetic manipulation of 6-phospho-fructo-kinase and fructose 2,6-biphosphate levels affects the extent to which benzoic acid inhibits the growth of Saccharomyces cerevisiae. Microbiology 147 403-410. 

Renz A. and Stitt M. 1993. Substrate specificity and product inhibition of different forms of fructo-kinases and hexokinases in developing potato tubers. Planta 190 166-175. 

Another group of enzymes, the kinases, have been examined in E. coli and Staphylococcus aureus. In E. coli a glucokinase is found which phos-phorylates glucose to glucose-6-phosphate in the presence of Mg++ and ATP, and mannose to mannose-6-phosphate. Fructose is inert. This kinase is quite stable to alcohol treatment. In addition, a specific fructo-kinase, which is readily destroyed by alcohol, is also found in extracts of E. coli. The nature of the reaction product is not known. Extracts of Staph, aureus have a specific glucokinase which does not phosphorylate fructose and mannose. 

Figure 19-3. Control of glycolysis and gluconeoge-nesis in the liver by fructose 2,6-bisphosphate and the bifunctional enzyme PFK-2/F-2,6-Pase (6-phospho-fructo-2-kinase/fructose-2,6-bisphosphatase). (PFK-1, phosphofructokinase-1 [6-phosphofructo-1 -kinase] ...

The second study concerns the enzyme that catalyzes the synthesis of "2-6," fructase-6-phosphate 2-kinase. The liver is composed of several types of cells. The major cell, the hepatocyte, constitutes about S0% of the cell population and contains about 99% of the protein, Hepatocytes carry out most of the metabolic functions of the liver, Castenodd. (1979) added glucagon to hepatocytes in culture and found that fructo e-6-phosphate 2-kinase decreased within the first minute of addition of the hormone. Addition of the hormone was intended to simulate, in part, hormonal changes that occur in the body during exercise. The observed decrease in enzyme activity is consistent with the dramatic drop in "2-6" that occurred in the running rat experiment. The work described thus far shows that "2-6" levels in the liver Increase or decrease under certain conditions. These facts, though interesting, do not directly indicate a function for "2-6,"... 

Markham, J.E. Kruger, N.J. Kinetic properties of bifunctional 6-phospho-fructo-2-kinase/fructose-2,6-bisphosphatase from spinach leaves. Eur. J. Biochem., 269, 1267-1277 (2002)... 

Chesney, J. Mitchell, R. Benigni, F. Bacher, M. Spiegel, L. Al-Abed, Y. Han, J.H. Metz, C. Bucala, R. An inducible gene product for 6-phospho-fructo-2-kinase with an AU-rich instability element role in tumor cell glycolysis and the Warburg effect. Proc. Natl. Acad. Sci. USA, 96, 3047-3052 (1999)... 

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