DERA

H. Moissan, Comp. Fend. 102, 1534 (1886) 103, 202, 256 (1886) Gmelins, Hanbuch derA.norganischen Chemie, System 5, 8th ed., Deutsche Chemische GeseUschaft, Vedag Chemie, Berlin, 1926, pp. 4—16. 

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Gmelin Handbuch derA.norganischen Chemie, Transurane, TeilJid, kment Vedag Chemie, Weinlieim, Germany, 1973. 

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The 2-deoxy-D-ribose 5-phosphate aldolase (RibA or DERA EC 4.1.2.4) is a class I enzyme that in vivo catalyzes the reversible addition of ethanal to D-glyceraldehyde... 

Axelsson, B. (1964). Kemisk analys av dentala silikatcement och deras losliga komponenter. Odontologisk Revy, 15, 150-68. 

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]. 

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... 

In addition to the enzyme s amino acid sequence, other parameters can affect the outcome of a biocatalytic process. For instance, a similar outcome in the aforementioned DERA-catalyzed statin synthesis was achieved by process improvements [21]. Using a thermostable variant of DERA (thermostability generally correlates well with tolerance to high concentrations of organic reagents or cosolvents), and fed-batch conditions, an efficient process that overcame sensitivity to high concentrations of chloroacetaldehyde was developed. 

Liu, J.J., Hsu, C.C. and Wong, C.-H. (2004) Sequential aldol condensation catalyzed by DERA mutant Ser238Asp and a formal total synthesis of atorvastatin. Tetrahedron Letters, 45, 2439-2441. 

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

Anregungszustand entspricht, daB zwischen diesem und dera Grundzustand tlber-gange unter Aufnahme bzw. Abgabe von Strahlung nioht mdglich sind. 

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)... 

Scheme 1.57 DERA approach to the atorvastatin side chain...

The flexibility of DERA enzymes makes them a valuable synthetic tool for the quick access to a range of polyoxgenated products, such as the cytotoxic agent epothilone A (Scheme 1.58). ... 

Of the known classes of aldolase, DERA (statin side chain) and pyruvate aldolases (sialic acids) have been shown to be of particular value in API production as they use readily accessible substrates. Glycine-dependent aldolases are another valuable class that allow access to p-hydroxy amino acid derivatives. In contrast, dihydroxy acetone phosphate (DHAP) aldolases, which also access two stereogenic centres simultaneously,... 

In a time course study on the conversion of ( )-l-phenylethanol 13 (X=H), formation of acetophenone was observed to a maximum of around 20% during the conversion of (S)- to (R)- alcohol which occurred over 24 h to give (R)-13 in 96 % yield, 99% e.e. The effect of ring substitution on the efficiency of the dera-cemization was notable. While para substituents (Cl, OMe, Me) gave good results, ortho derivatives could not be deracemized and the biocatalyst showed little activity towards meta substituted compounds. On addition of allyl alcohol, improvements in e.e. were obtained, particularly for the conversion of l-(m-methylphenyl)ethanol (from 21 to 94% e.e.). However these improvements did appear to be at the expense of yield (89% diminished to 55%). The authors sug-... 

Soon after he became Professor, he also became the President of the Kyoto University Alpine Club (1961). The first plan that he scheduled was to conquer an unclimbed summit in the Himalayas. Whoever an alpinist might be, he wants to try once to climb Mt. Everest, and that was Ono-dera s dream from his youth. He went to the Himalayas as a leader with six members of the club, and was successful in conquering Indrasan and Deo Tibba. The results were published in the Himalayan Journal, 24 (1963) 90-95, entitled The Ascent of Indrasan and Deo Tibba, by Ono-dera. The expedition organized and sent made the first ascent of Indrasan (6,221 meters) on October 13, 1962. The party also climbed Deo Tibba (6,000 meters). Onodera stayed in the base camp, encouraged the members, and advised them to move carefully. This great achievement had an important effect not only on young students, including members of his Institute, but also on all Japanese youth, especially alpinists. Also in 1967, Onodera went on another expedition, to India and Bhutan, but, unfortunately, this time he was not successful, as he could not get permission to ascend a peak from Bhutan. 

The following coating resins were used (1) a vinyl ester (Dera-kane 470 from Dow Chemical) (2) a polyester (Atlac 382-05 AC from ICI) and (3) four epoxy resin/hardener combinations. The details of the resins and hardeners used are shown in Table I. One of the epoxy/hardener combinations was represented by materials from two sources. 

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