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Nitrilase Biotransformations

The availability of ready for use nitrilase preparations [41] with the advantage of avoiding the laborious handling of whole cell biotransformation systems has simplified the reaction protocol substantially and prompted the screening of nitrilases [Pg.253]

A significantly different enzyme activity was noticed here depending on the ring size. Five-membered pyrrolidine-3-carbonitriles were formed close to their theoretical yields within a shorter reaction time (a maximum of 24 h) than six-membered piperidine-3- and 4-carbonitriles, which required transformation times within days. Nevertheless, the enzyme activities remained nearly unchanged over this time period. Nipecotic acid 11c could be prepared and isolated in 93% e.e., thus allowing an efficient and decisively short enantioselective synthesis of this heterocycUc amino acid [42], compared to existing literature procedures (Section [Pg.254]

N-Toluenesulfonyl protected acids were formed in enantioselectivities superior to N-carbobenzoxylated derivatives, a fact also observed throughout the work on carbocycUc y-amino acids. [Pg.254]

Although some product from ( )-12a was formed by NlT-106, pipecolic acid 12c could not be synthesized in a preparatively satisfying way, in particular because the amide formation is twice as high as the acid formation. A structural comparison of heterocycUc amino nitriles ( )-10a-( )-12a with carbocydic P-amino nitriles [Pg.254]

Not surprisingly, some nitrilase reactions were accompanied by the formation of the corresponding amides, such as pipecolic amide 12b (up to 10%) and pyrrolidine-3-carbo3amide 10b (for a discussion of nitrile hydratase activity of nitrilases see Section 15.3.3). [Pg.255]


The addition of HCN to aldehydes or ketones produces cyanohydrins (a-hydroxy nitriles). Cyanohydrins racemize under basic conditions through reversible loss of FiCN as illustrated in Figure 6.30. Enantiopure a-hydroxy acids can be obtained via the DKR of racemic cyanohydrins in the presence of an enantioselective nitriletransforming enzyme [86-88]. Many nitrile hydratases are metalloenzymes sensitive to cyanide and a nitrilase is usually used in this biotransformation. The DKR of mandelonitrile has been extended to an industrial process for the manufacture of (R)-mandelic acid [89]. [Pg.145]

Figure 8.13 Preparation of 3-ACPA and 3-ACHA via nitrilase-catalyzed biotransformation... Figure 8.13 Preparation of 3-ACPA and 3-ACHA via nitrilase-catalyzed biotransformation...
Strategic importance of biocatalyzed synthetic transformations in terms of eco-compatibility and cheaper processes has been widely stressed previously. Among the developed biotransformations catalyzed by nitrilases or nitrile hydratases/ amidases systems, a special interest is focused toward stereoselective reactions able to give access to molecules otherwise impossible to obtain by classical chemical routes. Hereby, selected examples aim to offer an overview of research in this direction. Examples of industrial processes using nitrile hydrolyzing biocatalysts are also illustrated. [Pg.377]

Very recently, all substrates reported in Tables 17.14 and 17.15, were submitted to biotransformations in the presence of fungal nitrilases from Fusarium solani 01 and... [Pg.386]

An analogous biotransformation of 3-cyanopyridine catalyzed by a nitrilase has been proposed for the production of nicotinic acid. Nitrilases from R. rhodochrous J1 (Mathew et al, 1988) and Nocardia globerula NHB-2 (Sharma et al., 2006) resting cells have been found to be highly efficient in the production of nicotinic acid (Figure 17.20). [Pg.400]

Fungal nitrilases immobilized on these columns were applicable to continuous biotransformation of heteroaromatic nitriles like 3- and 4-cyanopyridine, the products of which, nicotinic and isonicotinic acid, respectively, are of commercial interest. The enzyme from F. solani exhibited a higher stability than that from A. niger at 35 °C. The conversion of 3-cyanopyridine by the former enzyme was nearly quantitative within 24h [50], while it decreased by 30% within 15h in the case of the latter [49]. Similar differences in operational stabiUties were observed during conversion of 4-cyanopyridine. The stabiUty of the enzymes depended on the substrate used, both nitrilases being more stable during the conversion of 4-cyanopyridine in comparison with 3-cyanopyridine. [Pg.242]

In industrial biotransformations, hydrolytic reactions occupy a prominent position for the production of optically active amines, alcohols, and carboxylic acids. Compared with other reactions, hydrolytic reactions are feasible to scale up because they are cofactor-free, relatively simple, and chemically tunable systems. In addition to home-made whole-cell biocatalysts, which are considered to be more cost-effective for specific syntheses, some commercially available hydrolases, including lipases/esterases, epoxide hydrolases, nitrilases, and glycosidases, are also employed for the enantioselective production of chiral chemicals. [Pg.28]

Compilation of the biotransformation information has led to the postulation that the cloned Pseudomonas gene has both nitrilase and nitrile hydratase activities. This novel nitrile hydrolyzing activity is summarized in Figure 8. [Pg.58]

The NHase/amidase in R. erythropolis A4, a strain used to hydrolyze a wide spectrum of nitriles [16], was recently applied to the biotransformation of benzonitrile analogs used as herbicides (Figure 11.4) and the products and parent compounds were compared in terms of their acute toxicides [17]. In other rhodococcal strains, the same compounds, apart from dichlobenil, can also be hydrolyzed in a direct pathway catalyzed by a nitrilase [18,19]. It was demonstrated that the hydrolysis of the nitriles cannot itself be considered a detoxification. The two-step transformation may be especially important in the natural degradation of these compounds because unlike nitrilases, NHases and amidases are often constitutive enzymes, and their producer strains form the typical constituents of soil microflora [17, 20]. [Pg.252]

Figure 11.11 Biotransformation of 4-cyanopyridine into isonicotinic acid by a nitrilase-amidase cascade in a single reactor and a two-reactor system [56]. Figure 11.11 Biotransformation of 4-cyanopyridine into isonicotinic acid by a nitrilase-amidase cascade in a single reactor and a two-reactor system [56].
The bienzymatic approach was also used for the synthesis of a-alkyl-a-hydroxycarboxylic acids from ketones and cyanide. The conversion of ketones by HnLs is problematic because the reaction equilibrium is mainly on the side of the ketones and therefore these substrates are generally not quantitatively converted by HnLs ]68, 69]. Therefore, the presence of a second enzyme, such as a nitrilase, results in the establishment of an efficient cascade reaction. The feasibility of this biotransformation was demonstrated for the conversion of acetophenone plus cyanide at acidic pH-values by the recombinant whole-cell catalysts which simultaneously produced the nitrilase from P.Jluorescens EBC191 and the MeHnL. These cells converted acetophenone plus cyanide almost quantitatively to (S)-atroIactate (and (S)-atrolactamide) [61]. [Pg.261]

Martinkova, L. and Kfen, V. (2010) Biotransformations with nitrilases. Curr. Opin. Chem. Biol., 14, 130-137. [Pg.265]

Vejvoda, V., Sveda, O., Kaplan, O., Pfikrylova, V., EliSakova, V., Himl, M., Kubac, D., Pelantova, H., Kuzma, M., Kfen, V., and Martttikova, L. (2007) Biotransformation of heterocyclic dinitriles by Rhodococcus erythropolis and fungal nitrilases. Biotechnol. Lett.,... [Pg.267]

Kfen, V., and Martmkova, L. (2006) Immobilization of fungal nitrilase and bacterial amidase - two enzymes working in accord. Biocatal. Biotransform., 24, 414-418. [Pg.268]

Enantioselective transformations catalyzed by nitrilases often suffer from poor chiral recognition. Exceptions from this trend are benzaldehyde and phenylac-etaldehyde cyanohydrins. As an additional advantage, these substrates racemize readily at near-neutral pH via reversible loss of hydrogen cyanide representing good starting materials for dynamic kinetic resolution processes. This was demonstrated using 22 substituted phenyl and heteroaryl derivates 25 with two recombinant nitrilases a preparative biotransformation yielded (S)-phenyllactic add 26 in 84% yield and 96% ee on 1 g scale (Scheme 9.7) [31]. [Pg.249]

Previous reviews of this field of research focused mainly on the biocatal5dic uses of nitrilases [1], structure and function of nitrilases [2, 3], nitrilases in filamentous fungi [4], stereoselective biotransformations catalyzed by nitrile-converting enz5nnes [5], and the structure, function, and uses of nitrile hydratases [6]. For a comprehensive review of nitrile-converting enzymes known at the time, the study by Banerjee et al. [7] has been helpful. Some of the most recent reviews focused on nitrilases, specifically their sources, properties, and use, [8], and on methodologies for their screening [9]. [Pg.331]

Nitrile hydratases (NHases) exhibit broader substrate specificities than nitrilases, and they are more tolerant of sterically demanding substrates. In contrast, NHases mainly exhibit lower enantioselectivities than nitrilases, although biotransformations of a few specific nitriles by NHase proceeded with excellent enantioselectivities [5,6]. Low NHase enantioselectivity, however, can be compensated for by using enantiose-lective amidases in the next step. NHases are usually less thermostable than nitrilases, but a few of them are resistant to increased temperatures or organic solvent concentrations [8, 9]. The majority of characterized NHases are Fe or Co type, except for a new NHase with three metal ions (Co, Cu, Zn) reported in Rhodococcus jostii [85]. [Pg.340]


See other pages where Nitrilase Biotransformations is mentioned: [Pg.253]    [Pg.253]    [Pg.144]    [Pg.189]    [Pg.11]    [Pg.155]    [Pg.165]    [Pg.344]    [Pg.405]    [Pg.379]    [Pg.380]    [Pg.382]    [Pg.386]    [Pg.395]    [Pg.396]    [Pg.398]    [Pg.398]    [Pg.401]    [Pg.402]    [Pg.105]    [Pg.713]    [Pg.1450]    [Pg.55]    [Pg.254]    [Pg.257]    [Pg.344]   


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