Enzymatically derived aldouronic acids from Cryptomeria japonica arabinoglucuronoxylan

Abstract

Abstract An arabinoglucuronoxylan was extracted from the holocellulose of sugi ( Cryptomeria japonica ) wood with 10% KOH and subjected to hydrolysis by partially purified xylanase fraction from a commercial cellulase preparation “Meicelase”. Neutral sugars liberated were analyzed by size exclusion chromatography showing the presence of xylooligosaccharides up to xylohexaose. Aldouronic acids liberated were purified by preparative anion exchange chromatography. Their structures were identified by monosaccharide analysis, comparison of their volume distribution coefficients ( Dv s) with those of the authentic samples in anion exchange chromatography and 1 H and 13 C NMR spectroscopy, resulting in the characterization of eight aldouronic acids including acids consisting of two 4- O -Me-α-D-GlcA p residues and 3–5 D-Xyl residues. 1. Fr. 1-S1: (aldohexaouronic acid, MeGlcA 3 Xyl 5 ), O -β-Xyl p -(1 → 4)- O -β-D-Xyl p -(1 → 4)-[ O -(4- O -Me-α-D-GlcA p )-(1 → 2)]- O -β-Xyl p -(1 → 4)- O -β-D-Xyl p -(1 → 4)-D-Xyl 2. Fr. 1-S2: (aldopentaouronic acid, MeGlcA 3 Xyl 4 ), O -β-Xyl p -(1 → 4)-[ O -(4- O -Me-α-D-GlcA p )-(1 → 2)]- O -β-D-Xyl p -(1 → 4)- O -β-Xyl p -(1 → 4)-D-Xyl 3. Fr. 2-S1: (aldotetraouronic acid, MeGlcA 3 Xyl 3 ), O -(4- O -Me-α-D-GlcA p )-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -β-D-Xyl p -(1 → 4)-D-Xyl 4. Fr. 3-S1: (aldotetraouronic acid, GlcA 3 Xyl 3 ), O -(α-D-GlcA p )-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -β-Xyl p -(1 → 4)-D-Xyl, 5. Fr. 4-S1: (aldotriouronic acid, GlcA 2 Xyl 2 ), O -(4- O -Me-α-D-GlcA p )-(1 → 2)- O -β-D-Xyl p -(1 → 4)-D-Xyl 6. Fr. 4-S2: (MeGlc 4 MeGlcA 3 Xyl 5 ), O -β-D-Xyl p -(1 → 4)-[ O -(4- O -Me-α-D-GlcA p )]-(1 → 2)- O -β-D-Xyl p -(1 → 4)-[ O -(4- O -Me-α-D-GlcA p )]-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -β-D-Xyl p -(1 → 4)-D-Xyl 7. Fr. 6-S1: (MeGlcA 4 MeGlcA 3 Xyl 4 ), O -(4- O -Me-α-D-GlcA p )-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -[(4- O -Me-α-D-GlcA p )]-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -β-D-Xyl p -(1 → 4)-D-Xyl 8. Fr. 7-S1: (MeGlcA 3 MeGlc 2 Xyl 3 ), O -(4- O -Me-α-D-GlcA p )-(1 → 2)- O -β-D-Xyl p -(1 → 4)- O -[(4- O -Me-α-D-GlcA p )]-(1 → 2)- O -β-D-Xyl p -(1 → 4)-D-Xyl Fr. 4-S2 was a new acidic oligosaccharide. The distribution pattern of these vicinal uronic acid units along the D-xylan chain was discussed.