Fructose-6-phosphate synthesis

Although sucrose has not been synthesized by strictly chemical means, its synthesis has been accomplished by the use of enzymes from living organisms.86 An enzyme from the bacterium Pseudomonas saccharophila Doudoroff was allowed to act on D-glucose-l-phosphate in the presence of D-fructose. This synthesis gives little information about... 

An efficient asymmetric total synthesis of L-fructose combines the Sharpless asymmetric dihydroxylation with an enzyme-catalyzed aldol reaction. L-Glyceraldehyde, prepared from acrolein, is condensed to DHAP in a buffered water suspension of lysed cells of KI2 Escherichia coli containing an excess of L-rhamnulose-1-phosphate (Rha) aldolase E. coli raised on L-rhamnose as sole carbon source). The L-fructose phosphate obtained is hydrolyzed to L-fructose with acid phosphatase. Similarly, the RAMA-catalyzed condensation of D-glyceraldehyde with DHAP,... 

This enzyme is very specific it does not react with sorbose, fructose phosphates, glucose, or any other compound tested in place of fructose, and glucose-l-phosphate cannot replace UDPG. Unlike the case of sucrose phosphorylase, the equilibrium of this reversible reaction favors sucrose synthesis, and the presence of this enzyme in the cells of higher plants implicates this reaction in sucrose synthesis. 

In continuation of earlier work with over-expressed enzymes from E. coli (see Vol.25, Chapter 7, ref.44), D-tagatose 1,6-diphosphate has been synthesized from dihydroxyacetone by use of a combination of several enzymes including a newly isolated tagatose 1,6-bisphosphate aldolase. An efficient synthesis of D-fructose 1,6-diphosphate by use of four enzymes in a one pot operation has been described. D-[1- C] Fructose 6-phosphate has been prepared from C-enriched formaldehyde and D-ribose 5-phosphate by a formaldehyde fixing enzyme system from Methylomonas aminofaciens, and various C-substituted D-fructose phosphates have been obtained by enzymic methods from C-substituted pyruvate or L-alanine. ... 

Paper ionophoresis, sugars, Maurice Stacey s work, 17 Pectic acid, 350, 352,414 Pectin, 348, 350-353 Pectinic acid, 353 Pentulose, synthesis, 281 D-cryt/iro-Pentulose 5-phosphate, 289 Peptidoglycans, 167-168 Per-O-acetylated di-D-fructose dianhydride derivatives... 

The D-fructose 1,6-bisphosphate aldolase (FruA EC 4.1.2.13) catalyzes in vivo the equilibrium addition of (25) to D-glyceraldehyde 3-phosphate (GA3P, (18)) to give D-fructose 1,6-bisphosphate (26) (Figure 10.14). The equilibrium constant for this reaction of 10 strongly favors synthesis [34]. The enzyme occurs ubiquitously and has been isolated from various prokaryotic and eukaryotic sources, both as class I and class II forms [30]. Typically, class I FruA enzymes are tetrameric, while the class II FruA are dimers. As a rule, the microbial class II aldolases are much more stable in solution (half-lives of several weeks to months) than their mammalian counterparts of class I (few days) [84-86]. 

Figure 10.38 Multienzymatic scheme for the stereoselective synthesis oftwo equivalents ofxylulose 5-phosphate from fructose 1,6-bisphosphate.

The pentose phosphate pathway is an alternative route for the metabolism of glucose. It does not generate ATP but has two major functions (1) The formation of NADPH for synthesis of fatty acids and steroids and (2) the synthesis of ribose for nucleotide and nucleic acid formation. Glucose, fructose, and galactose are the main hexoses absorbed from the gastrointestinal tract, derived principally from dietary starch, sucrose, and lactose, respectively. Fructose and galactose are converted to glucose, mainly in the liver. 

Pyruvate kinase (PK) is one of the three postulated rate-controlling enzymes of glycolysis. The high-energy phosphate of phosphoenolpyruvate is transferred to ADP by this enzyme, which requires for its activity both monovalent and divalent cations. Enolpyruvate formed in this reaction is converted spontaneously to the keto form of pyruvate with the synthesis of one ATP molecule. PK has four isozymes in mammals M, M2, L, and R. The M2 type, which is considered to be the prototype, is the only form detected in early fetal tissues and is expressed in many adult tissues. This form is progressively replaced by the M( type in the skeletal muscle, heart, and brain by the L type in the liver and by the R type in red blood cells during development or differentiation (M26). The M, and M2 isozymes display Michaelis-Menten kinetics with respect to phosphoenolpyruvate. The Mj isozyme is not affected by fructose-1,6-diphosphate (F-1,6-DP) and the M2 is al-losterically activated by this compound. Type L and R exhibit cooperatively in... 

Figure 6.8 Versatile one-pot synthesis of D-iminocyclitols with fructose-6-phosphate aldolase...

Schurmann, M., Schurmann, M. and Sprenger, G.A. (2002) Fructose 6-phosphate aldolase and 1-deoxy-D-xy lulose 5-phosphate synthase from Escherichia coli as tools in enzymatic synthesis of 1-deoxysugars. Journal of Molecular Catalysis B, Enzymatic, 19, 247-252. 

Castillo, J.A., Calveras, J., Casas, J. et al. (2006) Fructose-6-phosphate aldolase in organic synthesis preparation of D-fagomine, /V-alkylated derivatives, and preliminary biological assays. Organic Letters, 8, 6067-6070. 

Sugiyama, M., Hong, Z.Y., Liang, RH. et al. (2007) D-Fructose-6-phosphate aldolase-catalyzed one-pot synthesis of iminocyclitols. Journal of the American Chemical Society, 129, 14811-14817. 

Franke, D., Machajewski, T., Hsu, C.-C. and Wong, C.-H. (2003) One-pot synthesis of L-fructose using coupled multienzyme systems based on rhamnulose-1-phosphate aldolase. The Journal of Organic Chemistry, 68 (17), 6828-6831. 

I, 7-diphosphate.170 1 (f> This tetrose phosphate is involved with phosphoenol pyruvate in the formation of shikimic acid via 3-deoxy-2-keto-D-ara6ino-heptonic acid 7-phosphate and, hence, of aromatic compounds.170(d) A synthesis of the tetrose phosphate has been described.170 1 Aldolase shows a high affinity for the heptulose diphosphate and, compared with that for D-fructose 1,6-diphosphate, the rate of reaction is about 60 %. The enzyme transaldolase, purified 400-fold from yeast, catalyzes the following reversible reaction by transfer of the dihydroxyacetonyl group.l70(o>... 

D-glucose-l-phosphate and D-fructose, Hassid, Doudoroff and Barker18 succeeded in crystallizing a non-reducing disaccharide which was indistinguishable from natural sucrose. It was thus that the first laboratory synthesis of sucrose was achieved. 

The enzymatic synthesis of sucrose also throws light on the formation of the furanose form of fructose in the sucrose molecule. The fact that sucrose is directly formed from D-glucose-l-phosphate and D-fructose supports Isbell and Pigman s34 and Gottschalk s85 evidence that the latter monosaccharide occurs in solution in an equilibrium mixture of furanose and pyranose forms. This makes it unnecessary to postulate a special mechanism of stabilization of a five membered (furanose) ring before the formation of compound sugars containing the D-fructose molecule.86... 

The interconversion of fructose-6-phosphate and fructose-1,6 bis phosphate is a control point in glycolysis and gluconeogenesis. Gluconeogenesis is a pathway which allows carbon atoms from substrates such as lactate, glycerol and some amino acids to be used for the synthesis of glucose, so it is in effect physiologically the opposite of... 

Sugiyama, M., Hong, Z., Whalen, L.J., Greenberg, W.A. and Wong, C.-H., Borate as a phosphate ester mimic in aldolase-catalyzed reactions practical synthesis of L-fructose and L-iminocyclitols. Adv. Synth. Catal. 2006, 348, 2555 - 2559. 

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