Sunday, August 10, 2008
P9
Aldolase-Catalyzed Synthesis of Unnatural Sugars and Iminocyclitols
Masakazu Sugiyama1, Zhangyong Hong2, William A. Greenberg2, and Chi-Huey Wong2. (1) AminoScience Laboratories, Ajinomoto Co., Inc., 1-1 Suzukicho, Kawasakiku, Kawasaki, Japan, (2) Department of Chemistry, The Scripps Research Institute, 10550 N Torrey Pines Rd, La Jolla, CA 92037
Facile chemoenzymatic methods for the synthesis of a variety of D- and L- iminocyclitols or L-sugars have been developed. The practicality of formerly reported methods using dihydroxyacetone phosphate (DHAP) aldolase was limited by the high cost and instability of DHAP. Here we discuss the three strategies toward the facile synthesis of sugar analogues using DHA(P) aldolases from readily available non-phosphoryrated donor substrates.
(1) Directed evolution of the L-rhamnulose 1-phosphate aldolase (RhaD) was employed to alter the donor substrate specificity of RhaD aldolase from DHAP to DHA. In vivo selection for the directed evolution using genetically engineered E. coli strain was constructed.
(2) RhaD aldolase was found to accept non-phosphorylated dihydroxyacetone (DHA) as a donor substrate in the presence of borate. We applied this discovery to develop a practical one-step synthesis of L-fructose and two-step synthesis of L-iminocyclitols.
(3) A one-pot synthesis was achieved using the recently discovered D-fructose 6-phosphate aldolse (FSA). FSA utilized DHA, hydroxyacetone, and 1-hydroxy-2-butanone as donor substrates to allow the synthesis of a variety of novel D-iminocyclitols in a concise fashion.
1) M. Sugiyama, C.-H. Wong et al., Bioorg. Med. Chem., 15, 5905-5911 (2007).
2) M. Sugiyama, C.-H. Wong et al., Adv. Synth. Catal., 348, 2555 – 2559 (2006).
3) M. Sugiyama, C.- H. Wong et al., J. Am. Chem. Soc., 129(47), 14811-14817 (2007).
(1) Directed evolution of the L-rhamnulose 1-phosphate aldolase (RhaD) was employed to alter the donor substrate specificity of RhaD aldolase from DHAP to DHA. In vivo selection for the directed evolution using genetically engineered E. coli strain was constructed.
(2) RhaD aldolase was found to accept non-phosphorylated dihydroxyacetone (DHA) as a donor substrate in the presence of borate. We applied this discovery to develop a practical one-step synthesis of L-fructose and two-step synthesis of L-iminocyclitols.
(3) A one-pot synthesis was achieved using the recently discovered D-fructose 6-phosphate aldolse (FSA). FSA utilized DHA, hydroxyacetone, and 1-hydroxy-2-butanone as donor substrates to allow the synthesis of a variety of novel D-iminocyclitols in a concise fashion.
1) M. Sugiyama, C.-H. Wong et al., Bioorg. Med. Chem., 15, 5905-5911 (2007).
2) M. Sugiyama, C.-H. Wong et al., Adv. Synth. Catal., 348, 2555 – 2559 (2006).
3) M. Sugiyama, C.- H. Wong et al., J. Am. Chem. Soc., 129(47), 14811-14817 (2007).
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