L-isoleucine 4-hydroxylase

Moreover, IDO stereoselectively hydroxylates several aliphatic L-amino acids as well as L-isoleucine [15]. It converts L-leucine and L-norvaline into (2S)-4-hydroxyleucine and (2S,4S)-4-hydroxynorvaline, respectively. When L-norleucine is used as the substrate, single diastereomers of (2S)-4-hydrox3morleucine and 

22 BIOCATALYTIC INTRODUCTION OF CHIRAL HYDROXY GROUPS USING OXYGENASES 

Cascade hydroxylation reactions of L-lle catalyzed by HilA and HilB. 

TABLE 22.1 Fe(ll)/aKG-Dependent Dioxygenases (Fe/aKG-Dos) Acting as Stereoselective Aliphatic Amino Acid Flydroxylases  

Fe/aKG-DOs Gene Bank Accession No. Origin AA Homology with IIX) (%)  

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Recently, we reported a novel metabolic pathway for L-isoleucine via (2S,3R,4S)-4-hydroxyisoleucine (HIL) and (2S,3R)-2-amino-3-methyl-4-ketopentanoic acid (AMKP) in Bacillus thuringiensis 2e2 [12,13]. HIL synthesis was found to be catalyzed stereose-lectively by a novel Fe/aKG-DO, L-isoleucine 4-hydroxylase (IDO) (Figure 22.2). This metabolic pathway fxmctions as an effective b)rpass pathway that compensates for the incomplete TC A cycle in Bacillus species [14]. 

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