L-leucine dehydrogenase

L-Leucine dehydrogenase in chiral L-amino acid synthesis 78... 

Fig. 14 Kinetic resolution of or-fcrf-leucine catalyzed by L-leucine dehydrogenase (L-LeuDH) for the preparation of D-tert-leucine with simultaneous NAD+ regeneration using NADH oxidase (Nox) from Lactobacillus brevis...

Sakakura A, Suzuki K, Nakano K, Ishihara K (2006) Chiral l,l -binaphthyl-2,2 -diammonium salt catalysts for the enantioselective Diels-Alder reaction with a-acyloxyacroleins. Org Lett 8 2229-2232 Sanwal BD, Zink MW (1961) L-Leucine dehydrogenase of Bacillus cereus. Arch Biochem Biophys 94 430-435... 

Significant research on LM enzyme encapsulation systems has also been conducted at the University of Hannover, West Germany. Scheper et al. (19) proposed the use of LMs to resolve racemic D,L-phenylalanine methyl ester with encapsulated chymotrypsin. This enzyme cleaves the ester bond of the L-isomer only. The process employed Adogen 464 (TOMAC) as an anion carrier, but the pHs used were such that any L-phenylalanine formed would be zwitterionic LM transport of zwitterions would be expected to be poor. Further work has included development of an LM enzyme reactor for detoxification of blood (33), reductive amination of a-ketoisocaproate by L-leucine dehydrogenase with a coencapsulated... 

The use of an LeuDH as an amino acid dehydrogenase showed a high L-enan-tiospecificity [24]. In this connection, an L-leucine dehydrogenase from Bacillus sphaericus has been applied very efficiently. The FDH from Candida boidinii is the preferred formate dehydrogenase for this process. The stability of this enzyme, which is available in technical quantities, has been remarkably improved by protein engineering and directed evolution [25], In particular the replacement of cys-... 

Amino acid racemase with low substrate specificity catalyzes racemization of leucine and various other amino acids, which are also a-deuterated in 2H20 during their racemization[63). Therefore, [4S-2H]-NADH was produced in the same manner as described above with the racemase and L-leucine dehydrogenase (E. C. 1.4.1.9), which is pro-S specific[35). 

Ansorge M B, Kula M R (2000). Production of recombinant L-leucine dehydrogenase from Bacillus cereus in pilot scale using the runaway replication system E. coli (pIET98). Biotechnol. Bioengin. 68 557-562. 

Similar to the work described by Spohn et al. [34], a trienzyme sensor was developed recently for the determination of branched-chain amino acids (L-valine, L-leucine, and L-isoleucine). Leucine dehydrogenase, NADH oxidase, and peroxidase were coimmobilized covalently on tresylate-hydrophylic vinyl polymer beads and packed into a transparent PILL tube (20 cm X 1.0 id), which was used as flow cell. The sensor was free of interferences from protein and NH4+ and it was stable for 2 weeks. The sensor system was applied to the determination of branched-chain amino acids in plasma with recoveries ranging from 98 to 100% [36],... 

K. F. Gu and T. M. S. Chang, Conversion of ammonia or urea into L-leucine, L-valine and L-isoleucine using artificial cells containing an immobilized multienzyme system and dextran-NAD+, glucose dehydrogenase for co-factor recycling, A 4/0, 11(1), 24-28 (1988). 

L-tert-leucine trimethylpyruvate leucine dehydrogenase + formate dehydroenase... 

Reductive amination reactions of keto acids are performed with amino acid dehydrogenases. NAD-dependent leucine dehydrogenase from Bacillus sp. is of interest for the synthesis of (S)-fert.-leucine [15-17]]. This chiral compound has found widespread application in asymmetric synthesis and as a building block of biologically active substances. The enzyme can also be used for the chemoenzy-matic preparation of (S)-hydroxy-valine [18] and unnatural hydrophobic bran-ched-chain (S)-amino acids. NAD-dependent L-phenylalanine dehydrogenase from Rhodococcus sp. [19] has been used for the synthesis of L-homophenyl-alanine ((S)-2-Amino-4-phenylbutanoic acid) [9]. These processes with water-soluble substrates and products demonstrate that the use of coenzymes must not... 

Figure 11 The putative catabolic pathway of L-leucine and its implications for strain improvement. For a promising host strain, the pathway to be blocked is indicated with thick double lines and the pathways to be fortified are indicated with thick arrows. Abbreviations for enzymes participating in the L-leucine catabolism and the acylation of tylosin VDH, valine (branched-chain amino acid) dehydrogenase BCDFI, branched-chain a-keto acid dehydrogenase IVD (AcdH), isovaleryl-CoA dehydrogenase (acyl-CoA dehydrogenase) MCC, 3-methylcrotonyl-CoA carboxylase EH, enoyl-CoA hydratase AcyA, mac-rolide 3-O-acyltransferase AcyBl, macrolide 4"-(9-acyltransferase.

Hanson, R. L., Singh, I, Kissick, T. E, Patel, R. N., Szarka, L. I, and Mueller, R. H. 1990. Synthesis of L-P-hydroxyvaline from a-keto-P-hydroxyisovalerate using leucine dehydrogenase from Bacillus sp. Bioorg. Chem.,18,116-130. 

Fig. 8 Synthesis of amino acids by a multienzyme system consisting of leucine dehydrogenase (LeuDH) catalyzing the reductive amination of the corresponding keto acid, L-lactate dehydrogenase (l-LDH), and lactate for the regeneration of NADH and urease for the in situ generation of ammonia. The coenzyme NAD+ was covalently bond to dextran, enzymes and dextran-coupled NAD+ were...

Fig. 35 Production of L-tert-leucine by reductive amination of trimethyl pyruvic acid catalyzed by leucine dehydrogenase (LeuDH) and formate dehydrogenase (FDH) for cofactor regeneration...

In a related approach, D,L-methionine can be efSdently deracemized to obtain the L-enantiomer using a multienzyme system consisting of D-amino acid oxidase, catalase, leucine dehydrogenase, and formate dehydrogenase. The a-keto acid 8 produced from the oxidation of the D-form is transformed into L-methionine 9 in the presence of ammonia, leucine dehydrogenase, and a stoichiometric amount of NADH. The NAD thus formed is recycled to NADH with ammonium formate and formate dehydrogenase [30] (Scheme 13.10). 

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