80877-72-1Relevant academic research and scientific papers
Convergent in situ Generation of Both Transketolase Substrates via Transaminase and Aldolase Reactions for Sequential One-Pot, Three-Step Cascade Synthesis of Ketoses
Lorillière, Marion,Guérard-Hélaine, Christine,Gefflaut, Thierry,Fessner, Wolf-Dieter,Clapés, Pere,Charmantray, Franck,Hecquet, Laurence
, p. 812 - 817 (2019/12/27)
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.
ISOMERISATION OF C4-C6 ALDOSES WITH ZEOLITES
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Page/Page column 25-28, (2014/03/25)
The present invention relates to isomerization of C4-C6 aldoses to their corresponding C4-C6 ketoses. In particular, the invention concerns isomerization of C4-C6 aldoses over solid zeolite catalysts free of any metals other than aluminum, in the presence of suitable solvent(s) at suitable elevated temperatures. C6 and C5 aldose sugars such as glucose and xylose, which are available in large amounts from biomass precursors, are isomerized to fructose and xylulose respectively, in a one or two-step process over inexpensive commercially available zeolite catalysts, containing aluminum as the only metal in the catalyst. The ketoses obtained are used as sweeteners in the food and/or brewery industry, or treated to obtain downstream platform chemicals such as lactic acid, HMF, levulinic acid, furfural, MMHB, and the like. FIG. 7
Broadening deoxysugar glycodiversity: Natural and engineered transaldolases unlock a complementary substrate space
Rale, Madhura,Schneider, Sarah,Sprenger, Georg A.,Samland, Anne K.,Fessner, Wolf-Dieter
supporting information; experimental part, p. 2623 - 2632 (2011/04/16)
The majority of prokaryotic drugs are produced in glycosylated form, with the deoxygenation level in the sugar moiety having a profound influence on the drug's bioprofile. Chemical deoxygenation is challenging due to the need for tedious protective group manipulations. For a direct biocatalytic de novo generation of deoxysugars by carboligation, with regiocontrol over deoxygenation sites determined by the choice of enzyme and aldol components, we have investigated the substrate scope of the F178Y mutant of transaldolase B, TalBF178Y, and fructose 6-phosphate aldolase, FSA, from E. coli against a panel of variously deoxygenated aldehydes and ketones as aldol acceptors and donors, respectively. Independent of substrate structure, both enzymes catalyze a stereospecific carboligation resulting in the D-threo configuration. In combination, these enzymes have allowed the preparation of a total of 22 out of 24 deoxygenated ketose-type products, many of which are inaccessible by available enzymes, from a [3 -8] substrate matrix. Although aliphatic and hydroxylated aliphatic aldehydes were good substrates, D-lactaldehyde was found to be an inhibitor possibly as a consequence of inactive substrate binding to the catalytic Lys residue. A 1-hydroxy-2-alkanone moiety was identified as a common requirement for the donor substrate, whereas propanone and butanone were inactive. For reactions involving dihydroxypropanone, TalBF178Y proved to be the superior catalyst, whereas for reactions involving 1-hydroxybutanone, FSA is the only choice; for conversions using hydroxypropanone, both TalBF178Y and FSA are suitable. Structure-guided mutagenesis of Ser176 to Ala in the distant binding pocket of TalBF178Y, in analogy with the FSA active site, further improved the acceptance of hydroxypropanone. Together, these catalysts are valuable new entries to an expanding toolbox of biocatalytic carboligation and complement each other well in their addressable constitutional space for the stereospecific preparation of deoxysugars.
Prebiotic carbohydrate synthesis: Zinc-proline catalyzes direct aqueous aldol reactions of α-hydroxy aldehydes and ketones
Kofoed, Jacob,Reymond, Jean-Louis,Darbre, Tamis
, p. 1850 - 1855 (2007/10/03)
Zn-proline catalyzed aldolisation of glycoladehyde gave mainly tetroses whereas in the cross-aldolisation of glycoladehyde and rac-glyceraldehyde, pentoses accounted for 60% of the sugars formed with 20% of ribose. The Royal Society of Chemistry 2005.
Anomerization of Furanose Sugars and Sugar Phosphates
Pierce, John,Serianni, Anthony S.,Barker, Robert
, p. 2448 - 2456 (2007/10/02)
Thermodynamic and kinetic parameters for the ring-opening and -closing reactions of several aldo- and ketofuanoses and their phosphate esters have been determined by NMR line-width and saturation-transfer methods.Cyclic forms interconvert via a single, acyclic carbonyl form under either acid or base catalysis.Ring-opening rates do not correlate with thermodynamic stability of the rings.For aldofuranose phosphates, α anomers open faster than β anomers; for ketofuranose phosphates the converse is observed.Intramolecular catalysis of anomerization by the phosphate group of sugar phosphates is documented.Biological and mechanistic implications of the observed kinetics are discussed.
