Pipecolic oxidase

L-Pipecolic acid, a key component of many antibiotic and anticancer biomolecules, serves as an important chiral pharmaceutical intermediate. We have developed an enzyme-coupled system consisting of zl -piperidine-2-carboxylate reductase (Pip2C) from Pseudomonas putida, glucose dehydrogenase (GDH) from Bacillus subtilis, and L-lysine a-oxidase from Trichoderma viride, affording L-pipecolic acid from L-lysine in high yield with an excellent enantioselectivity (Figure 10.2). ... 

In a similar way, D,L-pipecoUc add was converted to L-pipecolic acid [49]. However, the use of sodium borohydride, which slowly decomposes in aqueous solution, causes a significant rise in the pH value, which has to be controlled and which interferes with the necessary repeated cycles. Turner and Fotheringham expanded the applicability of the method, using milder and water stable reducing agents [50] and applying amino acid oxidases with either D- or L-spedficity. 

A variety of biochemical defects have been reported in patients with the Zellweger syndrome. These include a defect in the catabolism of pipecolic acid (D2) and increased plasma, biliary, and urinary levels of intermediates in bile acid synthesis (H4, M15, M30). More recently, the accumulation of very-long-chain fatty acids, such as hexacosanoic acid, has been noted (M32) and elevated plasma phytanic acid with decreased fibroblast phytanic acid oxidase activity reported (P13). 

Figure 16.7-9. One-pot chemo-enzymatic deracemisation of D,L-pipecolic acid catalyzed by D-amino acid oxidase (d-AAO). Utilization of catalase was not reported.

The elimination of the 6-amino group could occur via the action of an amine oxidase as has been suggested orPisum sativum (Mann and Smithies, 1955) or via the formation of saccharopine (Nabeta et al., 1973). Labeled pipecolic acid was found to serve as a precursor for the hydroxypipecolic acids of Umonium (Larher, 1976) and this conversion could proceed via the hydroxylation of 4,5-dehydropipecolic acid (baikiain). 

Flafner et al first reported an oxidase-catalyzed deracemization method using amino acids as the substrate and pkDAAOx or LAAOx from Crotalus adamanteus together with sodium borohydride as the chemical reductant in 1971 [42]. A procedure for the successful deracemization of amino acids was previously reported by Soda et al. [43]. They focused on proline and pipecolic acid as substrates for the production of L-enantiomer by deracemization because these substrates formed stable imines rather than unfavorable keto acids in water by DAAOx. However, the enzyme was denatured by the chemical reaction with sodium borohydride. Turner et al developed an effective production method for (R)- or (S)-amino acids and (S)-amines by a deracemization method using milder chemical reducing reagents such as sodium cyanoborohydride and artificial transfer hydrogenase [44,45]. 

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