e-journal

Recovery and fine structure variability of RGII sub-domains in wine (Vitis vinifera Merlot)

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† Background and Aims:
Rhamnogalacturonan II (RGII) is a structurally complex pectic sub-domain composed of more than 12 different sugars and 20 different linkages distributed in five side chains along a homogalacturonan backbone. Although RGII has long been described as highly conserved over plant evolution, recent studies have revealed variations in the structure of the polysaccharide. This study examines the fine structure variability of RGII in wine, focusing on the side chains A and B obtained after sequential mild acid hydrolysis. Specifically, this study aims to differentiate intrinsic structural variations in these RGII side chains from structural variations due to acid hydrolysis.

† Methods:
RGII from wine (Vitis vinifera Merlot) was sequentially hydrolysed with trifluoroacetic acid (TFA) and
the hydrolysis products were separated by anion-exchange chromatography (AEC). AEC fractions or total hydrolysates were analysed by MALDI-TOF mass spectrometry.

† Key Results:
The optimal conditions to recover non-degraded side chain B, side chain A and RGII backbone were 0.1 M TFA at 40 oC for 16 h, 0.48 M TFA at 40 oC for 16 h (or 0.1 M TFA at 60 oC for 8 h) and 0.1 M TFA at 60 oC for 16 h, respectively. Side chainBwas particularly prone to acid degradation. Side chainAand the RGII GalA backbone were partly degraded by 0.1 M TFA at 80 oC for 1–4 h. AEC allowed separation of side chain B, methyl-esterified side chain A and non-methyl-esterified side chain A. The structure of side chain A and the GalA backbone were highly variable.

†Conclusions:
Several modifications to the RGII structure of wine were identified. The observed dearabinosylation and deacetylation were primarily the consequence of acidic treatment, while variation in methyl-esterification,
methyl-ether linkages and oxidation reflect natural diversity. The physiological significance of this variability, however, remains to be determined.

Key words: Plant cellwalls, rhamnogalacturonan II, RGII, pectin, red wine, Vitis vinifera, Merlot, oligosaccharides, MALDI-TOF.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2014

Deskripsi Fisik

Annals of Botany 114: 1327–1337, 2014

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

114: 2014

Subjek

EKOFISIOLOGI TANAMAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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