Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage

Thomas Eixelsberger; Doroteja Horvat; Alexander Gutmann; Hansjörg Weber; Bernd Nidetzky

doi:10.1002/anie.201609288

Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage

Thomas Eixelsberger, Doroteja Horvat, Alexander Gutmann, Hansjörg Weber, Bernd Nidetzky

Research output: Contribution to journal › Article › peer-review

Abstract

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 UDPa-d-apiose (UDP-Api). We examined the mechanism of UDPApi/UDP-α-d-xylose synthase (UAXS) with site-selectively 2H-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

Original language	English
Pages (from-to)	2503 –2507
Journal	Angewandte Chemie - International Edition
Volume	56
Issue number	9
DOIs	https://doi.org/10.1002/anie.201609288
Publication status	Published - 2017

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Human- & Biotechnology

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title = "Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage",

abstract = "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 UDPa-d-apiose (UDP-Api). We examined the mechanism of UDPApi/UDP-α-d-xylose synthase (UAXS) with site-selectively 2H-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 ",

author = "Thomas Eixelsberger and Doroteja Horvat and Alexander Gutmann and Hansj{\"o}rg Weber and Bernd Nidetzky",

year = "2017",

doi = "10.1002/anie.201609288",

language = "English",

volume = "56",

pages = "2503 –2507",

journal = "Angewandte Chemie - International Edition ",

issn = "1521-3773",

publisher = "Wiley-VCH ",

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T1 - Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage

AU - Eixelsberger, Thomas

AU - Horvat, Doroteja

AU - Gutmann, Alexander

AU - Weber, Hansjörg

AU - Nidetzky, Bernd

PY - 2017

Y1 - 2017

N2 - 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 UDPa-d-apiose (UDP-Api). We examined the mechanism of UDPApi/UDP-α-d-xylose synthase (UAXS) with site-selectively 2H-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

AB - 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 UDPa-d-apiose (UDP-Api). We examined the mechanism of UDPApi/UDP-α-d-xylose synthase (UAXS) with site-selectively 2H-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

U2 - 10.1002/anie.201609288

DO - 10.1002/anie.201609288

M3 - Article

SN - 1521-3773

VL - 56

SP - 2503

EP - 2507

JO - Angewandte Chemie - International Edition

JF - Angewandte Chemie - International Edition

IS - 9

ER -

Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage

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