5-phosphate aldolase

Mechanistically similar to the pyruvate lyases, 2-deoxy-D-ribose 5-phosphate aldolase (EC 4.1.2.4) catalyzes the addition of acetaldehyde to D-glyceraldehyde 3-phosphate. 

Aldolases catalyze asymmetric aldol reactions via either Schiff base formation (type I aldolase) or activation by Zn2+ (type II aldolase) (Figure 1.16). The most common natural donors of aldoalses are dihydroxyacetone phosphate (DHAP), pyruvate/phosphoenolpyruvate (PEP), acetaldehyde and glycine (Figure 1.17) [71], When acetaldehyde is used as the donor, 2-deoxyribose-5-phosphate aldolases (DERAs) are able to catalyze a sequential aldol reaction to form 2,4-didexoyhexoses [72,73]. Aldolases have been used to synthesize a variety of carbohydrates and derivatives, such as azasugars, cyclitols and densely functionalized chiral linear or cyclic molecules [74,75]. 

Wong, C.-H. and Greenberg, W.A. (2007) Asymmetric synthesis using deoxyribose-5-phosphate aldolase. 

The cholesterol-lowering drug atorvastatin, marketed as Lipitor, is an example where biocatalysis research has been applied extensively and is in industrial use. The enzyme 2-deoxyribose-5-phosphate aldolase (DERA) has been a target of directed evolution for the production of atorvastatin intermediates [8,9,71]. DeSantis and coworkers [8,9] used structure-based... 

DeSantis, G., Liu, J., Clark, D.R et al. (2003) Structure-based mutagenesis approaches toward expanding the substrate specificity of D-2-deoxyribose-5-phosphate aldolase. Bioorganic and Medicinal Chemistry, 11, 43-52. 

Jennewein, S., Schurmann, M., Wolberg, M. et al. (2006) Directed evolution of an industrial biocatalyst 2-deoxy-D-ribose 5-phosphate aldolase. Biotechnology Journal, 1, 537-548. 

Figure 14.12 Asymmetric tandem aldol reaction using 2-deoxyribose-5-phosphate aldolase (DERA) and its application for production of Atorvastatin...

Gijsen, H.J.M. and Wong, C.-H. (1994) Unprecedented asymmetric aldol reactions with three aldehyde substrates catalyzed by 2-deoxyribose-5-phosphate aldolase. Journal of the American Chemical Society, 116 (18), 8422-8423. 

Several approaches to statin side-chain intermediates have so far been discussed. Whereas these chemoenzymatic approaches provide clear benefits over the chemical processes, they do not harness the tme potential of biocatalysis as the biotransformations have simply been inserted into the existing chemical route. Wong and co-workers have developed a more biosynthetic-hke approach by using a mutant 2-deoxyiibose-5-phosphate aldolase (DERA)... 

DEOXYRIBONUCLEASES 2 -Deoxyribonucleoside diphosphate, RIBONUCLEOTIDE REDUCTASE 2-DEOXYRIBOSE-5-PHOSPHATE ALDOLASE DEOXYTHYMIDINE KINASE DEP,... 

DHAP-dependent aldolases Pyruvate dependent aldolases Deoxyribose 5 -phosphate aldolase —h... 

Figure 6.2 Overview of biocatalytic routes to vastatin side chains. PLE pig-liver esterase, ADH alcohol dehydrogenase, HHDH halohydrin dehalogenase, DERA 2-deoxy-D-ribose 5-phosphate aldolase.

Another promising route was reported in patent and open hterature by both DSM and Diversa [13, 14]. This route employs a 2-deoxy-D-ribose 5-phosphate aldolase (DERA) that catalyzes a tandem aldol addition in which two equivalents of acetaldehyde (AA) are added in sequence to chloroacetaldehyde (CIAA) to produce a lactol derivative that is similar to the 3,5-dihydoxy side chain of synthetic statins (Figure 6.2e). Diversa screened environmental libraries for novel wild-type DERAs and identified an enzyme that was both tolerant to increased substrate concentrations and more active than DERA from E. coli in the target reaction [13]. 

Deoxy-D-Ribose 5-Phosphate Aldolase (DERAj-Based Routes to Statin Intermediates 1131... 

Table 6. Substrate tolerance of deoxy-D-ribose 5-phosphate aldolase a l. M - V"°> OH ...

Concerning aldolases, the cloning of enzymes is becoming more and more common. Thus the bacterial fuculose-1-phosphate aldolase (EC 4.1.2.17) and 2-deoxyribose-5-phosphate aldolase (EC 4.1.2.4) have been recently overexpressed in E. coli and their synthetic use has been examined.115,116... 

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