Aldolases fructose-biphosphate aldolase

D have an a-helix preceding the alft barrel this helix blocks the N-terminal end of the barrel fructose-biphosphate aldolase, 2-keto-3-deoxy-6-phospho- gluconate... 

Recently, a chemoenzimatic catalized Henry reaction has been reported by El Blidi et al.53 Nitroaldol cyclization between the masked 3-hydroxy-4-nitrobutyraldehyde 72 and dihydroxyacetone phosphate (DHAP) 73, catalyzed by fructose-1,6-biphosphate aldolase (RAMA), afforded the nitro-cyclohexane 74 (Scheme 24). 

Fructose 1,6-biphosphate aldolase from rabbit muscle in nature reversibly catalyzes the addition of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde 3-phosphate. The tolerance of this DHAP-dependent enzyme towards various aldehyde acceptors made it a versatile tool in the synthesis of monosaccharides and sugar analogs [188], but also of alkaloids [189] and other natural products. For example, the enzyme-mediated aldol reaction of DHAP and an aldehyde is a key step in the total synthesis of the microbial elicitor (—)-syringolide 2 (Fig. 35a) [190]. 

For the described approach, it is important to note that aldolases of different origin were tested and that, in contrast to L-rhamnulose-1-phosphate aldolase (RhuA), the D-fructose-1,6-biphosphate aldolase from rabbit muscle and L-fucu-lose-1-phosphate aldolase from E. coli were not active for DHAP/(R)-N- and (S)-iV-Cbz-prolinal condensation. Since RhuA accepts both, (S)-N- and (R)-N-Cbz prolinals, the chemo-enzymatic synthesis of both, hyacinthacines A and A2 isomers could be achieved. In conclusion, the origin and the particular enzyme itself... 

Hereditary fructose intolerance is caused by an autosomal recessive hereditary defect of the enzyme fructose-l-phosphate aldolase. Whenever fructose is supplied, severe hypoglycaemia and functional disorders occur in the liver, kidneys and CNS. The prevalence is estimated at 1 20,000 births. As with galactose intolerance, the gene which codes aldolase B is also localized on chromosome 9. This enzyme defect causes fructose-l-phosphate to accumulate in the liver and tissue. The cleavage of fructose-1,6-biphosphate is only slightly compromised since the enzymes aldolase A and C are available for this process. The consumption of phosphate and ATP in the tissue results in various functional disorders (i.) inhibition of gluconeogenesis in the liver and kidneys, (2.) increase in lactate in the serum with metabolic acidosis, (3.) decrease in protein synthesis in the liver, and (4.) functional disorders of the proximal tubular cells with development of Fanconi s syndrome, (s. pp 593, 594) (193, 194, 196, 198)... 

Aldolase (fructose-1,6-biphosphate aldolase EC 4.1.2,13) catalyzes the reversible conversion of fructose-1,6-biphos-phate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. The enzyme is a tetramer of identical subunits of 40 kDa. Three isoenzymes are identified to date aldolases A, B, and C. Aldolase A is the isoenzyme that is expressed in the RBC, but also in muscle and brain. 

Fructose 6 phosphate phosphofructokinase i ATP— ADP Fructose-1, 6-biphosphate aldolase i... 

The second stage of glycolysis forms glycer-aldehyde 3-phosphate. Under the catalytic action of aldolase, fructose 1,6-biphosphate is cleaved thus forming two triose phosphate isomers ... 

They have been widely used to synthesize deoxy/lluoro sugars or iminocyclitols (glycosidases inhibitors). The best known DHAP-dependent aldolase is probably fructose-1,6-biphosphate aldolase (EBP aldolase or FruA for the type I... 

FBP aldolases) catalyzing the coupling of DHAP with Ga3P 35 to form fructose-1,6-biphosphate 55 (Scheme 28.23). These enzymes do not require any co-factor and can be used in a straightforward reaction in aqueous buffered solutions, with a tolerance for certain organic solvents (DMSO/DMF) that can be thus used as co-solvents to obtain a better solubility of the substrates. Some immobilized catalysts were also obtained in view to increase the efficiency of the reaction notably toward selectivity. 

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