26207-44-3Relevant academic research and scientific papers
Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage
Eixelsberger, Thomas,Horvat, Doroteja,Gutmann, Alexander,Weber, Hansj?rg,Nidetzky, Bernd
, p. 2503 - 2507 (2017/02/23)
The C-branched sugar d-apiose (Api) is essential for plant cell-wall development. An enzyme-catalyzed decarboxylation/pyranoside ring-contraction reaction leads from UDP-α-d-glucuronic acid (UDP-GlcA) to the Api precursor UDP-α-d-apiose (UDP-Api). We examined the mechanism of UDP-Api/UDP-α-d-xylose synthase (UAXS) with site-selectively2H-labeled and deoxygenated substrates. The analogue UDP-2-deoxy-GlcA, which prevents C-2/C-3 aldol cleavage as the plausible initiating step of pyranoside-to-furanoside conversion, did not give the corresponding Api product. Kinetic isotope effects (KIEs) support an UAXS mechanism in which substrate oxidation by enzyme-NAD+and retro-aldol sugar ring-opening occur coupled in a single rate-limiting step leading to decarboxylation. Rearrangement and ring-contracting aldol addition in an open-chain intermediate then give the UDP-Api aldehyde, which is intercepted via reduction by enzyme-NADH.
