Structural characteristics of pectic polysaccharides and arabinogalactan proteins from Heracleum sosnowskyi Manden

Published Date

20 January 2016, Vol.136:1358–1369, doi:10.1016/j.carbpol.2015.10.041

Title 

Structural characteristics of pectic polysaccharides and arabinogalactan proteins from Heracleum sosnowskyi Manden

• Author 

• Evgeny G. Shakhmatov ^a
• Konstantin V. Atukmaev ^b
• Elena N. Makarova ^a,,

• aInstitute of Chemistry, Komi Science Centre, Urals Branch of the Russian Academy of Sciences, Pervomaiskaya St. 48, Syktyvkar 167982, Russia
• bInstitute for Problems of Chemical and Energetic Technologies, Siberian Branch of the Russian Academy of Sciences (IPCET SB RAS), Biysk 659322, Russia

Received 7 April 2015. Revised 9 October 2015. Accepted 12 October 2015. Available online 22 October 2015.

Highlights

• •
  Heracleum sosnowskyi pectic polysaccharide structures were characterized for the first time.
• •
  RG-I side chains are formed out of T-β-d-Galp, 1,4-β-d-Galp, 1,6-β-d-Galp.
• •
  AGP carbohydrate backbone consists of 1,3- and 1,3,6-β-d-Galp residues.
• •
  AGP side chains consist of 1,6-β-d-Galp, 1,5-α-l-Araf, 4-OMe-β-d-GlcpA.

Abstract

Polymers with different structures were isolated from the aboveground part of Heracleum sosnowskyi Manden. The sequential treatment of Heracleum with water, HCl solution, and (NH₄)₂C₂O₄ solution was observed to decrease the arabinogalactan proteins (AGP) content and increase the pectins content in the extracted polysaccharides. The linear region of the HS_O-I polysaccharide having the highest yield was found to be composed mainly of partially methylesterified homogalacturonan fragments, whereas the branched region was made up of fragments of rhamnogalacturonan I whose core represents 1,2-α-l-rhamno-1,4-α-d-galacturonan. The carbohydrate side chains of the branched region are linked to the α-l-Rhap core residues via the 1,4-glycosidic bond and consist chiefly of T-β-d-Galp, 1,4-β-d-Galp and 1,6-β-d-Galp residues indicating the presence of the 1,4-β-d-galactan. NMR spectroscopy revealed the carbohydrate moiety of the AGP molecule to consist mainly of 1,3- and 1,3,6-β-d-Galp residues. The side chains comprised 1,6-β-d-Galp, terminal 4-O-Me-β-d-GlcpA, and β-d-Galp.

Keywords

• Heracleum sosnowskyi
• Pectin
• Arabinogalactan protein
• Structure
• NMR

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