28 L-スレオニンアルドラーゼを利用したMycestericin DおよびシアロルイスX類似体の合成(口頭発表の部)

概要

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L-Threonine aldolases which catalyze the aldol cleavage of threonine to glycine and acetaldehyde in metabolic pathways also catalyze the aldol condensation using glycine as enolate source; however, the enzymes have not been widely used in organic synthesis since Yamada succeeded in the isolation and crystallization of the enzyme from Candida humicola (AKU 4586). The enzyme accepts a broad range of aldehydes and produced multifunctional β-hydrox-α-amino acids, which are constituents of many naturally occurring compounds with interesting biological activities. The substrate specificities of aldehydes acceptors are summarized in Table I. It was found that the aldolase from Candida humicola catalyzes the condensation of glycine and acetaldehyde to form a 93:7 mixture of L-allo-threonine and L-threonine, and moreover, high erythrolthreo ratio was also observed when an oxygen is at the β-position of the aldehydes. A peptide-like mimetic of sialyl Lewis x, which mediates the early stage of adhesion between leukocyte and activated endotherial cells, and Mycesterin D, which is isolated from Isaria sinclairii and shows novel type of immune supress activity, were synthesized by using L-threonine aldolase catalyzed reaction as a key step. The details will be discussed.
1995-09-01