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Enzymatic resolution for the preparation of enantiomerically enriched D ‐β‐heterocyclic alanine derivatives using Escherichia coli aromatic L ‐amino acid transaminase
Author(s) -
Cho ByungKwan,
Park HyungYeon,
Seo JooHyun,
Kinnera Koteshwar,
Lee BonSu,
Kim ByungGee
Publication year - 2004
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20280
Subject(s) - alanine , transaminase , enzyme , chemistry , aspartate transaminase , biochemistry , alanine transaminase , organic chemistry , resolution (logic) , alanine aminotransferase , amino acid , stereochemistry , biology , alkaline phosphatase , artificial intelligence , computer science , endocrinology
Abstract An enzymatic resolution was carried out for the preparation of enriched β‐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°C, directly leading to make the potassium salt of the corresponding N ‐acetyl‐β‐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 β‐heterocyclic L ‐alanine derivatives have similar molecular structures, they showed different reaction rates and enantioselectivities. The relative reactivities of the transaminase toward the β‐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 (δ, Å) from the nitrogen of α‐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 (δ) becomes indicative value of k cat / K M of the enzyme to the substrate, the relative reactivities of the β‐heterocyclic L ‐alanine derivatives were successfully correlated with E /δ, and the relationship was confirmed by our experiments. © 2004 Wiley Periodicals, Inc.