PMID:15459908
| Citation |
Cho, BK, Park, HY, Seo, JH, Kinnera, K, Lee, BS and Kim, BG (2004) Enzymatic resolution for the preparation of enantiomerically enriched D-beta-heterocyclic alanine derivatives using Escherichia coli aromatic L-amino acid transaminase. Biotechnol. Bioeng. 88:512-9 |
|---|---|
| Abstract |
An enzymatic resolution was carried out for the preparation of enriched beta-heterocyclic D-alanine derivatives using Escherichia coli aromatic L-amino acid transaminase. The excess of pyrazole, imidazole, or 1,2,4-triazole reacted with methyl-2-acetamidoacrylate in acetonitrile in the presence of potassium carbonate at 60 degrees C, directly leading to make the potassium salt of the corresponding N-acetyl-beta-heterocyclic alanine derivatives. After the acidic deprotection of the N-acetyl group, 10 mM of racemic pyrazolylalanine, triazolylalanine, and imidazolylalanine were resolved to D-pyrazolylalanine, D-triazolylalanine, and D-imidazolylalanine with 46% (85% ee), 42% (72% ee), and 48% (95% ee) conversion yield in 18 h, respectively, using E. coli aromatic L-amino acid transaminase (EC 2.6.1.5). Although the three beta-heterocyclic L-alanine derivatives have similar molecular structures, they showed different reaction rates and enantioselectivities. The relative reactivities of the transaminase toward the beta-heterocyclic L-alanine derivatives could be explained by the relationship between the substrate binding energy (E, kcal/mol) to the enzyme active site and the distance (delta, A) from the nitrogen of alpha-amino group of the substrates to the C4' carbon of PLP-Lys258 Schiff base. As the ratio of the substrate binding energy (E) to the distance (delta) becomes indicative value of k(cat)/K(M) of the enzyme to the substrate, the relative reactivities of the beta-heterocyclic L-alanine derivatives were successfully correlated with E/delta, and the relationship was confirmed by our experiments. |
| Links |
PubMed Online version:10.1002/bit.20280 |
| Keywords |
Alanine/chemical synthesis; Aromatic-L-Amino-Acid Decarboxylases; Binding Sites; Computer Simulation; Enzyme Activation; Escherichia coli/enzymology; Heterocyclic Compounds/chemical synthesis; Kinetics; Models, Chemical; Models, Molecular; Protein Binding; Stereoisomerism; Tyrosine Transaminase/analysis; Tyrosine Transaminase/chemistry |
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