15384-37-9Relevant articles and documents
Acidity and lactonization of xylonic acid: A nuclear magnetic resonance study
Hummel, Michael,Leppikallio, Mikko,Heikkinen, Sami,Niemelae, Klaus,Sixta, Herbert
, p. 416 - 428 (2010)
In acidic aqueous solutions the xylonic acid/xylonate equilibrium is coupled with the formation of the γ-and δ-lactones. The γ-lactone is formed more readily, whereas the Δ5-lactone can only be observed in traces at very low pH values (13C NMR, both the lactone hydrolization constant and the acid dissociation constant could be determined (KL = 4.08, pKa1 = 3.65 ± 0.34). Further, a second deprotonation of one of the hydroxyl groups could be observed at very high pH (pKa2 = 13.3 ± 0.76). Copyright Taylor & Francis Group, LLC.
Converging conversion - using promiscuous biocatalysts for the cell-free synthesis of chemicals from heterogeneous biomass
Pick, André,Sieber, Volker,Sutiono, Samuel
supporting information, p. 3656 - 3663 (2021/06/06)
Production of chemicals from lignocellulosic biomass has been proposed as a suitable replacement to petrochemicals. However, one inherent challenge of biomass utilization is the heterogeneity of the substrate resulting in the presence of mixed sugars after hydrolysis. Fermentation of mixed sugars often leads to poor yield and generation of multiple by-products, thus complicating the subsequent downstream processing. System biocatalysis has thus been developed in recent years to address this challenge. In this work, several novel enzymes with broad substrate promiscuity were identified using a sequence-based discovery approach as suitable biocatalysts in a conversion ofd-xylose andl-arabinose, two major constituents of hemicellulose found in plant biomass. These promiscuous enzymes enabled simultaneous biotransformation ofd-xylose andl-arabinose to yield 1,4-butanediol (BDO) with a maximum production rate of 3 g L?1h?1and a yield of >95%. This model system was further adapted toward the production of α-ketoglutarate (2-KG) from the pentoses using O2as a cosubstrate for cofactor recycling reaching a maximum production rate of 4.2 g L?1h?1and a yield of 99%. To verify the potential applicability of our system, we attempted to scale up the BDO and 2-KG production fromd-xylose andl-arabinose. Simple optimization and reaction engineering allowed us to obtain BDO and 2-KG titers of 18 g L?1and 42 g L?1, with theoretical yields of >75% and >99%, respectively. One of the promiscuous enzymes identified together with auxiliary promiscuous enzymes was also suitable for stereoconvergent synthesis from a mixture ofd-glucose andd-galactose, predominant sugars found in food waste streams and microalgae biomass.
Synthesis of key fragments of leiodelide A
Chellat, Mathieu F.,Proust, Nicolas,Lauer, Matthew G.,Stambuli, James P.
supporting information; experimental part, p. 3246 - 3249 (2011/08/22)
The synthesis of all key fragments of the marine macrolide leiodelide A is described. The polyoxygenated northern subunit is derived from d-xylose, while the southern subunit is rapidly assembled via an aldol reaction and Horner-Wadsworth-Emmons olefination. This highly convergent approach will allow for rapid modification and assembly of several isomers of leiodelide A, which may be necessary considering the assignment of leiodelide B has been previously shown to be incorrect.
