Platform chemicals and polymer precursors can be produced via enzymatic pathways starting from lignocellulosic waste materials. The hemicellulose fraction of lignocellulose contains aldopentose sugars, such as d-xylose and l-arabinose, which can be enzymatically converted into various biobased products by microbial non-phosphorylated oxidative pathways. The Weimberg and Dahms pathways convert pentose sugars into α-ketoglutarate, or pyruvate and glycolaldehyde, respectively, which then serve as precursors for further conversion into a wide range of industrial products. In this review, we summarize the known three-dimensional structures of the enzymes involved in oxidative non-phosphorylative pathways of pentose catabolism. Key structural features and reaction mechanisms of a diverse set of enzymes responsible for the catalytic steps in the reactions are analysed and discussed.
- Ketoglutarate-semialdehyde dehydrogenase
- Non-phosphorylative pathways
- Pentose catabolism
- Sugar acid dehydratase