Aspartate derivatives

Alkylation of amino acids.1 This base is preferable to LDA for dideprotonation of di-f-butyl N-formylaspartate (1) to give 2. The dianion is alkylated by CH3I, CH2 CHCH2Br, and C6H5CH2Br to give a mixture of / - and a-alkylated aspartate derivatives (3 and 4) in a ratio of ca. 7 2. As expected, the /3-alkylated a-amino acid esters 3 are optically pure surprisingly, the products 4 are also optically active and, after crystallization, can be obtained in optical yields of 60%. 

FIGURE 3.4 The common pathway of the aspartate-derived amino acids in Corynebacteria. The mnemonic of the genes involved are shown in parentheses below the enzymes responsible for each step. Dotted lines indicate multiple enzymatic steps, and 16 is L-aspartic acid, 17 is L-aspartyl phosphate, 18 is L-aspartate semialdehyde, 19 is L-lysine, 20 is L-homoserine, 21 is L-isoleucine, 22 is L-threonine, and 23 is L-methionine. 

Molecular organization and regulation of the biosynthetic pathway for aspartate-derived amino acids in Corynebacterium glutamicum, Ind. Microorg. 1993, 97. 

Since Corynebacterium glutamicum does not possess a PEPsynthetase, no [3- CjPEP isotopomers can be formed from pyruvate. Thus, any [3- C]oxaloac-etate isotopomers must result from the action of PyrCx in vivo and their relative abundance allows to quantitate the relative contributions of PEPCx and PyrCx to oxaloacetate synthesis. In the aspartate derived from oxaloacetate a content of isotopomers labelled in C-3 but not in C-2 similarly high as that in pyruvate was found (Fig. 8 c), suggesting synthesis of oxaloacetate from pym-... 

I., and Tauch, A. (2003) The complete Corynebacterium glutamicum ATCC 13032 genome sequence and its impact on the production of L-aspartate-derived amino acids and vitamins. 

In the last decade, it has become clear that the chloroplast is the main site, if not the sole site, for the biosynthesis of the nutritionally essential aspartate-derived amino acids (Fig. 1) in plant leaves [1,2]. For example, isolated intact chloroplasts carry out the light-driven synthesis of lysine, threonine, and isoleucine from labeled aspartic acid and malic add [3]. This can be considered a photosynthetic process since ATP and NADPH produced in light are thought to be used directly (Fig. 1) to drive the synthetic reactions [3]. 

Fig. 2. Effect of plant age on light- and ATP/ NADPH-dependent biosynthesis of aspartate-derived amino adds by both intact chloroplasts and plastid extracts. Activity in plastids from 7 day old plants exressed as nmol/mg chlorophyll/hour were as follows light control ...

Kahnowski J, Bathe B, Bartels D, Bischoff N, Bott M, Burkovski A, Dusch N, Eggeling L, Eikmanns BJ, Gaigalat L, et al. (2003). The complete Corynebacterium glutamicum ATCC 13032 genome sequence and its impact on the production of L-aspartate-derived amino acids and vitamins. J Biotechnol, 104, 5-25. 

Besides the oxazolidinones and sultams, esters also participated in the azidation reaction. For example, electrophilic azidation of silyl ester enolate with trisyl azide provided mainly the antf- -silyl azide (eq 30). Introduction of the azide into aspartate derivatives provided precursors to 2,3-diaminosuccinic acid (eq 31). This reaction gave a single diastereomer in moderate yield. 

The glycolytic intermediate pyruvate and the TCA cycle intermediate oxaloac-etate are direct precursors of the aspartate-derived amino acids. Thus, to improve L-lysine production, their supply has to be increased in a balanced manner. Withdrawal of oxaloacetate from the TCA cycle requires replenishment of the... 

Scheme 19.12 Asymmetric epoxidation of homoallylic carbamates with aspartate derivative 33.

Scheme 19.14 Asymmetric Baeyer-Villiger oxidation with aspartate-derived catalyst 33.

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