Fructose crystal structure

D. Erion, S- J- Pilkis, M. R. El-Maghrabi, and W. N. Lipscomb, The allosteric site of human liver fructose 1,6-bisphosphatase. Analysis of six AMP site mutants based on the crystal structure, J. Biol. Chem. 269 27732 (1994). 

Two different enzymatically active forms of PFK could be identified which may be considered the R and T form in the framework of the symmetry model. The R form possesses a high affinity for the substrate fructose-6-P, the T form binds fructose-6-P with lower affinity. Upon binding of the inhibitor phosphoenolpyruvate, PFK converts to the T form. The enzyme is foimd in the R form upon binding the substrates (ATP or fructose-6-P) or the activator (ADP). There exist high resolution crystal structures of both forms. 

Figure 9.9 shows the crystal structure of two of the subunits of phosphofructokinase from B. stearothermophilus. In the complete enzyme, the subunits are disposed symmetrically about three mutually perpendicular axes. Each of these axes is a twofold symmetry axis, which means that rotating the entire structure by half of a full circle (180°) around the symmetry axis results in an identical structure. This rotation is shown diagramatically in figure 9.10. Because ADP is a product of the enzymatic reaction as well as an allosteric activator, it binds at both the catalytic and allosteric sites (see figs. 9.9 and 9.10). The catalytic site for fructose-6-phosphate in each subunit is at the interface of the subunit with one of its neighbors, and the allosteric site is at the interface with a different neighbor. 

Cooper, S. J., Leonard, G. A., McSweeney, S. M., Thompson, A. W., Naismith, J. H., Qamar, S., et al. The Crystal Structure of a Class II Fructose-1,6-Bisphosphate Aldolase Shows a Novel Binuclear Metal-Binding Active Site Embedded in a Familiar Fold. Structure 1996, 4, 1303-1315. 

Hall, D. R., Leonard, G. A., Reed, C. D., Watt, C. I., Berry, A., Hunter, W. N. The Crystal Structure of Escherichia coli Class II Fructose-1,6-Bisphosphate Aldolase in Complex with Phosphoglycolohydroxamate Reveals Details of Mechanism and Specificity. J. Mol. Biol. 1999, 287, 383-394. 

The crystal structure of fructose has been studied by Eiland and... 

Taniguchi, T. and Uchiyama, T., The crystal structure of di-D-fructose anhydride III, produced by inulin d-fructotransferase, Carbohydrate Res., 107, 255-262, 1982. 

The crystal structure of sucrose has been established by X-ray diffraction and neutron diffraction studies. The packing of sucrose molecules in the crystal lattice is determined mainly by hydrogen bond formation between hydroxyl groups of the fructose moiety. As an example of the type of packing of molecules in a sucrose crystal, a projection of the crystal structure along the a axis is shown in Figure 4-15. The dotted square represents one unit cell. The crystal faces indicated in this figure follow planes between adjacent sucrose molecules in such a way that the... 

For the carbohydrates especially, the amount of available crystal structural data decreases sharply with molecular complexity [479]. With the exception of the cyclodextrins, discussed in Part III, Chapter 18, there are less than 40 crystal structure analyses of oligosaccharides, of which less than 10 are trisaccharides, one is a tetrasaccharide, and one a hexasaccharide (Part III, Chap. 18). The majority of the basic monosaccharides that are the subunits of the polysaccharides that occur naturally have been studied for example, the pyranose forms of /7-arabinose, a-xylose, a- and -glucose, / fructose, a-sorbose, a-mannose, a- and -galactose, a-fucose, a-rhamnose, N-acetyl glucosamine, and mannosamine (Box 13.2). How-... 

Johnson, K.A., Chen, L., Yang, H., Roberts, M.F., and Stec, B., 2001, Crystal structure and catalytic mechanism of the MJ0109 gene product A bifunctional enzyme with inositol monophosphatase and fructose 1,6-bisphosphatase activities. Biochemistry 40 618-630. 

S. J. Cooper, G.A. Leonard, S.M. McSweeney, A.W. Thompson, J.H. Naismith, S. Qamar, A. Plater, A. Berry, and W.N. Hunter. 1996. The crystal structure of a class II fructose-1,6-bisphosphate aldolase shows a novel hinuclear metalbinding active site embedded in a familiar fold Structure 4 1303-1315. (PubMed)... 

C.A. Hasemann, E.S. Istvan, K. Uyeda, and J. Deisenhofer. 1996. The crystal structure of the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase reveals distinct domain homologies Structure 4 1017-1029. (PubMed)... 

The crystal structure of the entire 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase, a key bifunctional regulator of both glycolysis and gluconeogenesis, has been solved at 2.0 A resolution. The entire enzyme is a homodimer of 55kDa subunits arranged in a head-to-head fashion, with each monomer consisting of an independent kinase and phosphatase domain. The location of y-5 -ATP and inorganic phosphate in the kinase and phosphatase domains,... 

Polarisation of the substrate carbonyl group appears to be achieved in yet a third way by mammalian glucose 6-phosphate isomerase, which interconverts glucose and fructose 6-phosphates, The crystal structure of the rabbit enzyme in complex with the reactive intermediate analogue o-arabinohydroxamic acid Ki = 0.2 pM) (in its hydroximic form) reveals a cluster of four water molecules hydrogen bonded to each other, to the counterparts of 01 and 02 of the enediolate intermediate and to an active site arginine. Grotthus mechanisms of proton transfer between the two tautomers of the enediolate probably occur. 

Fructose 1,6-diphosphatase hydrolyses off the 1-phosphate in the step which commits the substrate to gluconeogenesis. The mammalian enzyme, a homodimer, is richly allosteric, as befits an enzyme at a metabolic branchpoint. It catalyses a single displacement, mediated by no less than four metal ions three Mg " sites and one K " site have been observed in the crystal structure. The nucleophilic water may be activated by proton transfer from Glu98. The very large claim has been made that by alteration of the conditions of crystallisation, the on-enzyme equilibrium can be switched from fructose-6-phosphate and inorganic phosphate to fructose-6-phosphate and metaphosphate. Given the... 

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