Convergent in situ Generation of Both Transketolase Substrates via Transaminase and Aldolase Reactions for Sequential One‐Pot, Three‐Step Cascade Synthesis of Ketoses

Abstract

We describe an efficient three-enzyme, sequential one-pot cascade reaction where both transketolase substrates are generated in situ in a convergent fashion. The nucleophilic donor substrate hydroxypyruvate was obtained from l-serine and pyruvate by a transaminase-catalyzed reaction. In parallel, three different (2S)-α-hydroxylated aldehydes, l-glyceraldehyde, d-threose, and l-erythrose, were generated as electrophilic acceptors from simple achiral compounds glycolaldehyde and formaldehyde by d-fructose-6-phosphate aldolase catalysis. The compatibility of the three enzymes was studied in terms of temperature, enzyme ratio and substrate concentration. The efficiency of the process relied on the irreversibility of the transketolase reaction, driving a shift of the reversible transamination reaction and securing the complete conversion of all substrates. Three valuable (3S,4S)-ketoses, l-ribulose, d-tagatose, and l-psicose were obtained in good yields with high diastereoselectivity.

Biocatalysis: Enzymatic Synthesis for Industrial Applications

“…Fessner and Clapes engineered fructose‐6‐phosphate aldolase (FSA) from E. coli to convert alkanones and alkanals into chiral β‐hydroxyl ketones/aldehydes [115a] . FSA was also combined with a transketolase and a transaminase for sequential one‐pot synthesis of l ‐ribulose, d ‐tagatose, and l ‐psicose [115b] . For a practical synthesis, the Sun group utilized FSA(A129S) in E. coli cells (30 g CDW L −1 ) to convert formaldehyde ( 58 , 3 m ) and dihydroxyacetone ( 59 , 3 m ) into l ‐erythrulose ( 60 , Scheme 21).…”

Recent Advances in the Substrate Selectivity of Aldolases

“…Along the same line of thought, the synthesis of ketoses has recently been carried out by a convergent generation of both nucleophile and electrophile substrates for a sequential one-pot three-step cascade. 115 This strategy comprised a combination of three thermostable enzymes including FSA Ecoli , transketolase from Geobacillus stearothermophilus (TK Gst ), and L-α-transaminase from Thermosinus carboxydivorans (TA Tca ). FSA Ecoli generated the TK Gst electrophile by cross-aldol addition of HE to formaldehyde or homoaldol addition of HE, whereas TA Tca provided the HPA nucleophile from the transamination reaction of L-serine to HPA using pyruvate as the amine acceptor, yielding L-Ala (Scheme 28).…”

“…Along the same line of thought, the synthesis of ketoses has recently been carried out by a convergent generation of both nucleophile and electrophile substrates for a sequential one-pot three-step cascade . This strategy comprised a combination of three thermostable enzymes including FSA Ecoli , transketolase from Geobacillus stearothermophilus (TK Gst ), and l- α-transaminase from Thermosinus carboxydivorans (TA Tca ).…”

Biokatalyse: Enzymatische Synthese für industrielle Anwendungen

“…‐aldehyde herzustellen [115a] . Die FSA wurde zudem mit einer Transketolase und einer Transaminase kombiniert, um eine sequentielle Eintopfsynthese von l ‐Ribulose, d ‐Tagatose und l ‐Psicose zu ermöglichen [115b] . Für eine praktikable Synthese nutzte die Gruppe von Sun FSA(A129S) in E.‐coli ‐Zellen (30 g BTM L −1 ), um Formaldehyd ( 58 , 3 m ) und Dihydroxyaceton ( 59 , 3 m ) in l ‐Erythrulose ( 60 , Schema 21) zu überführen [114] .…”